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Courtship and combat behavior in Gopherus berlandieri

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Courtship and combat behavior in Gopherus berlandieri
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Weaver, W. G ( William Glenn ), 1936-
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v, 69 leaves : ill., map. ; 28 cm.

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Cloaca ( jstor )
Courtship ( jstor )
Eggshells ( jstor )
Female animals ( jstor )
Gender discrimination ( jstor )
Head ( jstor )
Legs ( jstor )
Mating behavior ( jstor )
Species ( jstor )
Tortoises ( jstor )
Animal behavior ( lcsh )
Dissertations, Academic -- Zoology -- UF
Texas tortoise ( lcsh )
Turtles ( lcsh )
Zoology thesis Ph. D
City of Jacksonville ( local )
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bibliography ( marcgt )
non-fiction ( marcgt )

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Thesis - University of Florida.
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Manuscript copy.
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Vita.

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COURTSHIP AND COMBAT BEHAVIOR

IN GOPHERUS BERLANDIERI











By
WILLIAM GLENN WEAVER, JR.












A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
LN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY










UNIVERSITY OF FLORIDA
December, 1967














ACKNOWLEDGEMENTS


I was assisted in this investigation by a grant and facilities from the Welder Wildlife Foundation at Sinton, Texas. National Science Foundation grant (NSF GB 3738) to Dr. Walter Auffenberg partially supported some of the field and laboratory work. The Florida State Museum and the University of Florida Graduate School also provided support. Francis L. Rose generously provided Information and materials for certain sections of this paper. The drawn figures were prepared by

Mr. Nell Payne and Dr. Walter Auffenberg.

I am particularly indebted to Dr. Walter Auffenberg whose active Interest, unique biological perspective, and personal example guided me throughout the investigation.














TABLE OF CONTENTS


Page
ACKNOWLEDGEMENTS . . . . . . . . . . . . I

LIST OF TABLES . . . . . . . . . . . . . Iv

LIST OF FIGURES . . . . . . . . . . . . v

INTRODUCTION . . . . . . . . . . . . . I

FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS . . . . . . 5

INTERRELATIONSHIPS OF BEHAVIOR AND ECOLOGY . . . . . . 6

METHODS . . . . . . . . . . . . . . 8

BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS IN COURTSHIP AND COMBAT. . 15


COURTSHIP IN GOPHERUS BERLANDIERI . . . . . .

COURTSHIP IN OTHER GOPHERUS SPECIES . . . . . COMBAT IN GOPHERUS BERLANDIERI . . . . . . .

COMBAT IN OTHER GOPHERUS . . . . . . . .

BEHAVIORAL ELEMENTS COMMON TO COURTSHIP AND COMBAT . EXPERIMENTS. . . . . . . . . . . .

The Open Square Tests . . . . . . . .
The Closed Square Tests . . . . . . .
The Cloaca Scent Tests. . . . . . . .
Hormone Injections. . . . . . . . .

DISCUSSION . . . . . . . . . . . .

BIBLIOGRAPHY . . . . . . . . . . .


. . 34

. 41 . . 43

. . 47

. .52

* . 54

* . 54 . . 56 . . 60 . . 60

62

. . 70














LIST OF TABLES


Behavioral Elements in Tortoise Courtship and Combat. Stages of Courtship Observed in Gopherus berlandleri. Stages in the Courtship of Goherts polphenus . Results of the Open Square Experiments . . . Results of the Closed Square Experiments . . . Results of the Cloaca Scent Tests . . . . .


Page
. 20 31 . 40 55 . 58 . 59













LIST OF FIGURES


Page
1. Ranges of Pleistocene and Recent igrus Species. . . 4 2. The Open Square Apparatus ... . . . . . 10

3. The Closed Square Apparatus. . . ..... . . . 11
4. Scent Testing Chamber. ................. 12
5. External View of Actively Secreting Chin Glands of a Male
.RhtW h..erlandlerI .............. . .. 13
6. Histological Section of the Chin Gland of a Hale
~93heruM berlandleri . . . . . . . . 18
7. Diagrammatic Representation of the Protein Bands In the
Chin Gland Secretion of Gbherus Species . . . 19 8. Action Patterns of Head Bobbing . . . . . . 23

9. Stages of Courtship In GooeUs 2r1nd rl. . . *.. 33 to10. Seal Dlmorphism In Gph berlandiLer. . . . 35













INTRODUCTION


The acuity of sex and species discrimination in mammals and birds is largely a function of ecological sympatry with other closely related species and therefore is a behavioral isolating mechanism. Recent work on fossil and living tortoises suggests that courtship behavior in tortoise species with a long history of sympatry is also more complex and discriminating than in allopatric species. A high discriminatory ability may persist in tortoise species currently allopatric, but only in those species pairs whose fossil record reveals a prior sympatry. Sympatric species which morphologically are prevented from interbreeding, such as Geocihelone travancorica and G. elegans, do not have a high discriminatory ability (Auffenberg, 1964).

The four extant species of the genus Soherus are allopatric. However, fossil specimens from northern Mexico and the western United States show that certain species of the genus were sympatric during the Pleistocene (Fig. 1). Thus the extant species provide an opportunity to investigate the influence of prior sympatry (Pleistocene) on the courtship behavlor of species which have since become allopatric. The objectives of this investigation are:

(1) to describe and analyze the courtship and combat behavior of

one of these speclesGoohrus berlandlerl;

(2) to compare this behavior with that known for the other living

species of Gopherus;






2

(3) to search for behavioral elements which have their origin in

mutually exclusive courtship patterns resulting from the prior

sympatry of Gooherus species.























Figure 1
Ranges of Pleistocene and Recent Goherus species. Solid colors represent ranges of extant species. Horizontal lines represent Pleistocene range of the poglyhemus group; vertical lines represent the Pleistocene range of aqassizi group. Squares show probable area of overlap.
















FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS


The earliest known tortoises are represented by fossils from the

Eocene of Africa and North America. The earliest North American genus is Stylemys, known from the Eocene (Auffenberg, 1964). The genus Gopherus, a descendant of Stylemys, is represented in North America from the Oligocene to the Recent (Hay, 1908; Auffenberg, 1964). At least as early as the irvingtonian stage of the Pleistocene Gopherus was already divided into its two extant species groups; the polyphemus group, and the aassizi group (Auffenberg, 1966b). Gopherus polyphemus of the southeastern United States and G. flavomarginatus of north central Mexico comprise the polyphemus group. Gopherus acasslzi of the southwestern United States and northwestern Mexico, and G. kerlandleri of southeastern Texas and northeastern Mexico comprise the aessizi group (Fig. 1).
Wermuth and Mertens (1961) consider all living Go2pherus populations as subspecies of G. polyphemus. Most workers (Auffenberg, 1966b; Carr, 1952; Grant, 1960) treat each of the four populations as distinct species, with which I concur.














INTERRELATIONSHIPS OF BEHAVIOR AND
ECOLOGY IN SQPIFILS

The ecology and habits of only two species of Gopherus are reasonably well known. Populations of _. aqassizi were studied in Utah by Woodbury and Hardy (1948), and G. berlandlerl has been studied in southeastern Texas (Auffenberg and Weaver, in press). Additional studies are

in progress on G. Plyphemus.

Specimens of Gopherus berlandler have no permanent daily retreat as do those of G. polyphemus, flavoMarl natus, and some G. aoassizl. Over most of the range of .. berlandleri each Individual occupies a pallet which is little more than a sloping ramp rarely deep enough to lower the anterior edge of the shell below the surface. The deeper end of older pallets may be sufficiently overhanging to cover the entire shell. This is the normal shelter on the clayey soils throughout most of the species' range. On more sandy soils some Individuals dig a burrow to which they return each day for most of their lives.

All the available evidence on tortoise activity indicates that
there is a positive correlation between shelter type and extent of activity range. Where q. berlandleri do not dig burrows they are largely nomadic. However burrow inhabiting individuals maintain a restricted activity range (Auffenberg and Weaver, in press).

The range of Gopherus aassizi is ecologically more variable than
that of the other living species of Goherus. Consequently populations of this species display considerable variation in ecologically related









behavior (W. Auffenberg field notes, 1962, 1963, 1964). Individuals in Sonora, Mexico, are nomadic all year, wandering in the dry arroyos of the area. Their shelter consists of a hollow scraped into the base of the arroyo wall. Further north, in the vicinity of Pima County, Arizona, the tortoises hibernate in specific winter shelters which are usually enlarged ground squirrel burrows. They are deep enough so that the posterior end

of the tortoise's shell is flush with the arroyo wall (Auffenberg, in press). At the extreme northern end of the range, in the area described by Woodbury and Hardy (1948), the tortoises have different ranges and shelters in summer and winter. In the summer they move from the upper reaches of the arroyos onto the flats where they excavate short burrows. In the winter they hibernate in communal burrows excavated in the arroyo walls. The seasonal changes of shelter are accompanied by seasonal changes of activity ranges. The summer and winter activity ranges do not overlap.

Gopherus polyghemus usually lives on sandy soil where it constructs a long, usually nonbranched burrow. New burrows may be constructed by adult individuals, but normally each individual uses a single burro throughout its life. Thus individuals of k. polyphemus have a restricted activity range (Auffenberg, in press).

Very little is known of G. flavomarginatus except that it excavates burrows in the playa soils of the Chihuahuan desert community in Mexico.

The presence or absence of an individual activity range has an

effect on courtship. Tortoises, such as G. polXphemus, which have individual activity ranges must leave their customary area in order to mate. Nomadic tortoises, such as G. berlandleri, regularly make contact with other tortoises. Therefore the portion of courtship involved in finding the opposite sex might be expected to differ in each of the above circumstances.















METHODS


Field and laboratory studies were performed to investigate the

courtship and combat behavior of Gopherus berlandlierl. The field work, begun in November, 1963, and completed in October, 1967, represents a total of 103 days.

It is difficult to obtain detailed information in the field to

clarify the sequential behavioral events of courtship and combat behavior. These tortoises are nomadic, small, shy, and reach maximum population densities in relatively thick, thorny brush. Many days were spent in the field without seeing courtship or combat, yet this paper represents the most intensive investigation of tortoise courtship and combat behavior published.

Laboratory experiments were designed to analyze behavior sequences, specifically the nature and importance of the cues used by A. berlandleri to distinguish sex in its own species. I rejected fully the idea of making the study entirely experimental. Observations of such complex

behavioral Interactions as courtship and combat made only on captive animals do not necessarily accurately reflect similar behavior in nature (Carpenter, 1962). My experiences have shown that tortoises kept together soon become accustomed to one another with the result that the frequency of courtship or combat behavior is reduced. Such tortoises evince renewed courtship or combat behavior when strange individuals are Introduced.






9

All of the courtship and combat observed In the field suggested that the front and rear portions of the tortoise were the most likely sources of olfactory cues relating to sex and species identification. The most obvious possible source of odoriferous material at the anterior end of the tortoise is the chin glands described in a later section. The cloaca was considered a probable source of olfactory cues at the posterior end. Cloacal scent is known to be important in sex discrimination in Geochelone carbaria and G. denticulata (Auffenberg, 1965). Movements of the tortoise were potentially important visual cues. The experiments with G. berlandlerl were designed to Investigate the roles of odors from the cloacal and chin glands and tortoise movement in courtship and combat behavior. The following testing devices were used in the experiments.

The open square.-These tests were based on the hypothesis that

there is no differential investigative response between male and female tortoises to other male and female tortoises and to controls. The test apparatus (Fig. 2) consisted of an open topped box. The floor was covered by screen wire. In the center of the box was a felt square. A mall, removable cage with wire sides was placed on rubber mats within the felt square on the floor of the large box. A Grayson-Statler vacuumswitch-sensor (Model E4690.) was connected to one of the wire sides of the small test cage and to a digital counter and a Grayson-Statler drinkometer panel counter (Models E4690A-1 and #3700A, respectively). The switch operated on a .06 millivolt differential which apparently was not detectable by the tortoises and assured maximum sensitivity. A circuit from electrical ground to the sensor was closed when the tortoise, grounded by the screen on the floor and the water dampened felt, touched the wire sides of the small cage. The digital counter recorded each closure of the circuit.








































Figure 2

The open square apparatus. A, removable cage; B, pen containing experimental tortoise; C, vacuum tube sensor; D, wire leads from sensor to digital counter. The pen, B, is five feet in length and width and 18 inches high.







































Figure 3

Closed square apparatus. A, removable cage; B, five gallon aquarium; C, air tight plastic seal; D, hose providing air to tortoise acting as stimulus.








































Figure 4

Scent testing chamber. A, pen containing experimental tortoises; B, jars containing odor stimulus; C, leads to sensor and digital counters. The chamber is six feet long at the front, four feet wide, and one foot high.

































*.I% ~id
4


Figure 5 External view of actively secreting chin glands, G, of a male Gopherus

berlandlerl.









The closed square.-Both Ive and preserved tortoises were used as stimuli to test the hypotheses that male and female tortoises respond equally to the sight and movement of other male and female tortoises. The closed square apparatus included that of the open square, but with the addition of an aquarium placed inside of the small, removable cage (Fig. 3). The top of the aquarium was sealed with a plastic bag fitted around a wood frame attached to the top of the aquarium. Air was provided to the animal by means of a long plastic hose.

The scent chamber.-A metal bottomed cage (Fig. 4) was used as a chamber in which reaction to scents was tested. Glass Jars with wire fronts were recessed into the front wall of this chamber. One GraysonStatler sensor was connected to the wire front of each of the jars. Samples of potentially important scent producing material was placed in the Jars. A circuit was closed when a tortoise's nose touched the wire

front of the Jars.

Hormone inlections.-Thyroxine, progesterone, and testosterone were injected subcutaneously to certain individuals in an effort to stimulate courtship or combat behavior. Injections of these hormones were made to also evaluate their role in the functioning of certain glands characteristically appearing on the chins of the species of Gopherus (Fig. 5). The glands, described later, are believed to influence courtship and combat behavior in Gopherus.

Photographs.-Photographs were made of tortoises engaged in various aspects of courtship and combat behavior. Both 8-mm and 16-mm motion picture film was used. Numerous 35-mm photographs were made, particularly in the field. The motion pictures and still photographs were used to evaluate the type and extent of each behavioral element occurring in courtship

and combat behavior.













BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS IN COURTSHIP AND COMBAT

As in other animals the reproductive activities of Goherus

berlandlerl are an Interaction of physiological and behavioral elements.
While the scope of this paper is not to trace the major hormonal and other chemical changes affecting courtship and combat behavior, one such aspect in G. berlandleri is of such relevance that it is included here.

From the start of this investigation in November, 1963, field observations of G. berlandlerl suggested that breeding behavior in this specles seemed to be correlated with the enlargement of a pair of large integumentary glands located ventrally and slightly medially on each mandibular remus (Fig. 5). Smith and Brown (1946) reported them as being found only in G. berlandlerl and interpreted them as degenerate capsules of connective tissue. However in his description of Gooherus berladlerl, Agassiz (1857) compared the chin glands of this species with the similar glands of G. polyphemus. Grant (1936) had already reported chin glands in G. aassilzi and lately Legler and Webb (1961) have described them in G. flavomariqlnatus. Among tortoises these glands are known only in species of Goherus. Chin glands are well known in rabbits, where their secretion is used to mark territorial boundries (Mykytowycz, 1965). In Goherus the glands are larger in males than in females, and larger in G. aqgassizi and G. berlandlerl than in G. polyphemus or G. flavomarainatus.
Auffenberg (1966a) found that female G. polyphemus rubbed their









forearms against the jaw in the region of the glands during courtship. I have observed similar behavior by male G. polvohemus. There is an enlarged scale on the foream of all species of Sopherus which is in the proper position to be rubbed across the gland. This scale is best developed in G. Dolyphemus and G. flavomarginatus. An investigation of the histological properties of the gland (Fig. 6) and an electrophoretic analysis of the chin gland secretion was begun in January, 1967 (Rose, Weaver, and Drotman, ms). Histological examinations showed that they are functional in both males and females and are similar in structure to mammal lan sebaceous glands. They open to the outside by two or three ducts, and their secretory activity varies seasonally. In the Brownsville, Texas, area the glands of adult males begin to enlarge in June, and by July they are fully enlarged in both adult males and females. In nature the glands of specimens from this population remain enlarged until at least December. Most specimens maintained in an indoor pen on a fifteen hour day had the glands enlarged until early January. By the end of January the glands of most of the tortoises had receded. These tortoises were moved to a large outdoor pen in the Gainesville, Florida, area on February 1, 1967. The glands of all tortoises had fully receded a week later and no secretory material could be obtained by gently squeezing the gland as was possible in previous months.

Electrophoretic analyses of the glandular secretions in species

of Gopherus show that the secretion contains proteins, an esterase, and three classes of lipids. The lipid classes are triglycerides, fatty acids, and a steroid, cholesterol. Interspecific variation exists in the number of esterase bands and in the proteins present in the secretion.



























Figure 6

Histological section of the chin gland of a male Gopherus berlandleri. This section, made In November, 1966, shows collecting duct lined with epithelial cells. The mass in the duct is composed of cells that have built up their products and have been discharged into the lumen as is typical of holocrine glands. The base of the'gland is at the bottom of the photograph.











CO






















B F A



















+



Figure 7

Diagrammatic representation of the protein bands in the chin gland secretion of Gopherus species. B, Gopherus berlandieri; F, G. flavomarginatus; A, G. agassizi. The females but none of the males of the living species of Gopherus have a negative protein band.








Table I
Behavioral Elements in Tortoise Courtship and Combat


Head bobbing















Trailing


Geochelone travancrice (Auffenberg, 1964) G. carbonaria (Auffenberg, 1965; Snedigar and Rokosky,

1950)
G. denticulata (Auffenberg, 1965) Gooherus agassizi (Nichols, 1957; Woodbury and Hardy,
1948)
G. berlandler (Householder, 1950) G. flavomarginatus (Legler and Webb, 1961) G. Polyphemus (Auffenberg, 1966) Geochelone carbonaria (Snedigar and Rokosky, 1950) G. elephantopus (Watson, 1963) G. pardalls (Watson, 1962) Gopherus agassizi (Nichols, 1957) G. berlandleri (Hamilton, 1944) G. flavomarginatus (Legler and Webb, 1961) G. polyphemus (Auffenberg, 1966) Honous areolatus (Eglis, 1963)


Courtship position


Smelling


Homous areolatus (Eglis, 1962) Geochelone carbonaria (Auffenberg, 1965) G. denticulata (Auffenberg, 1965) Gopherus aqassizi (Camp, C. L., 1916)








Table I continued

G. berlandlerl (Householder, 1950)
G. polyvhemus (Auffenberg, 1966) Humus areolatus (Eglis, 1963)

Biting Chersne anulata (Rose, 1950)
Geochelone denticulata (Beltz, 1954)
G. elephantopus (Heller, 1903)
Gopherus agassizi (Woodbury and Hardy, 1948; Camp, 1916; Grant, 1946)
G. berlandler (Householder, 1950)
PIoyphemus (Auffenberg, 1966) Homopus areolatus (EglIs, 1963)
Testudo raeca (Domerque, 1899; NikoIskil, 1915; Watson, 1962)

Ramming Cheargine anaulata (Rose, 1950)
Geochelone carbonaria (Auffenberg, 1965)
denticulata (Auffenberg, 1965; Beltz, 1954)
G. elephantous (Ditmars, 1910; DeSola, 1930)

.. oculifera (Fitzsimmons, 1935)
G. ravancorica (Auffenberg, 1964)
Gopherus aqassilzi (Nichols, 1953; Miller, 1932)
G. flavomarginatus (Legler and Webb, 1961)
J. nolvehemus (Carr, 1952)
Testudo raeca (Watson, 1962; NikolskIl, 1915)








Table 1 continued

Circular movement of courting pair
Gopherus aqassilzi (Woodbury and Hardy, 1948)
G. polyphemus (Auffenberg, 1966)
Homopus areolatus (Egils, 1963)


Vocal Izat Ion Presentation


Geochelone carbonarla (Snedigar and Rokosky, 1950) G. denticulata (Grant and DeSola, 1934) g. elephantopus (Watson, 1962; Heller, 1903; DeSola,

1930)
G. oculifera (Fltzslmmons, 1935) G. pardalls (Watson, 1962) Gopherus berlandlerl (Householder, 1950) Testudo irSeca (Watson, 1962; Nikolskil, 1915) Geochelone elephantopus (DeSola, 1930) Gopherus eqassi (Householder, 1950) G. polyphemus (Auffenberg, 1966)












































SECONDS
0 1
Figure 8
Action patterns of head bobbing. A, Gopherus berlandieri; B, G. agassizi; C, G. polyphemus.


- O









The protein concentration in females of all species of Goherus is much lower than in males. Females of all species of Gopherus had a cathodel migrating band which was absent in males (Fig. 7).

The courtship and combat of tortoises is a complex series of behavioral Interactions. The particular sequence of these elements vary interspecifically, and in some species some elements are absent. Certain behavioral elements have been recorded frequently enough in different and unrelated species to imply the existence of a generalized type of tortoise courtship or combat consisting of common behavioral elements. Table 1 lists nine behavioral elements of courtship or combat behavior

which are found in species of Gopherus. At present more courtship and combat behavior is known for species of Gooherus than for any other tortoise species. Thus Gopherus is here used as a comparative base in considering behavior in other tortoise species. Listed in Table I are also other tortoise species for which each of the behavioral units found in Gopherus be idlerl have been observed.

Head bobbinq-This movement is known for most tortoises and is performed in a characteristic fashion in different taxa (Egils, 1962). It is also one of the most frequently observed movements of tortoises

during courtship and combat. Eglis (1962) recognized that head movements in tortoises are latolent (lateral) or dirolent (straight). Eglis stated that the head movement of living species of Gopherus is basically dirolent. In Gopherus the neck is usually fully extended and the head is nodded vertically. The action pattern diagrams (Fig. 8) compares the duration, magnitude, and frequency of the vertical bobbing in three Gopherus species.









Individuals of all species of Gpherus bob their head when objects, such as food, are being smelled. it also occurs in meetings between two or more tortoises, and in shern reaches its greatest frequency during courtship and combat. Bobbing Is performed by both sexes, but in courtship the male bobs more actively than the female. Low intensity bobbing is performed when the head is not fully extended. Bobbing movements are often observed when the head is nearly completely retracted, but are associated with breathing and not olfaction. Head bobbing sequences are variable in length and have no discernible pattern correlated with either sex or species in Gopherus, except that the sequences are usually longer during social interactions than when food or feces are being smelled. The bobs performed in courtship and combat are apparently identical. The only clearly demonstrated function of head bobbing in tortoises is that of a species recognition in Geochelone carbonaria and G. denticulata in which the head movement is lateral (latolent) and has been demonstrated to act as a species specific visual signal (Auffenberg, 1965).

Trailing.-This behavioral unit (Stage I, Table 2) marks the start of courtship, and to a lesser extent combat. A male trails either a female in courtship or a male in combat. In Gopherus berlandleri courtship the male walks behind the female with his head extended, bobbing at irregular intervals. This behavior occurs at the beginning of courtship or combat, and may last for nearly an hour. Male G. berlandleri make no attempt to overtake the female during this early stage. If she stops, he stops; the rate of the female's activity influences that of the male. The male's attention is directed toward the female during this stage, and his behavior is dependent on hers. She often grazes during this period. In the courtship of G. polyphemus the female often walks






26

actively toward the male. Obviously trailing will eventually bring the male and female together physically, but the significance of its rituallike cadence in the early part of courtship in j. berlandlerl is unknown.

Eglis (1963) reported an instance of a male Homopus areolatus

following a female in a peculiar manner: The male's front feet were limp and the entire locomotion was accomplished by pushing motions of the rear feet.

Courtship position.-A distinct courtship stance has been reported only for HMus areolatus. However in confrontations between captive male Gopherus polvhemus a stance or positioning of bodies occurs consistently enough to be considered In this behavioral category. In Jgggags the male faces the female with their shells at a 900 angle (Eglis, 1963). This positioning is accomplished by the male's rushing around first one side and then the other of the female. In meetings between male Gopherus eolyphemus a similar position may also be achieved. The position is achieved by the more aggressive specimen, but seems more dependent on the timidity of the nonaggressive male than on strenuous efforts by the aggressive male as in Homoous areolatus. No similar positioning has been reported for other species of Gopherus; nor have I observed any.

Olfaction.-Male tortoises appear to smell various areas of females or other males in all the courtship and combat encounters observed, and in those reported in detail in the literature. The movement associated with olfaction in Gopherus is the head bob. However the head bobbing observed in most courtship or combat situations differs in minor but consistent ways from those observed when food or feces are being examined. These later head movements in iGoherus have a predominant forward motion.








Olfaction in Gphers Is a simple dirolent motion with little of the vertical component which essentially characterizes head bobbing as seen In courtship or combat. Thus a distinction exists between the types of head movements performed when odor is the only stimulus, as opposed to the head movements seen in the head bobbing of courtship or combat when factors other than, or in addition to, olfaction are involved. During meetings between tortoises head bobbing of the kind observed when food or feces are examined occur repeatedly. In these true olfactory movements, as opposed to head bobbing, the head is directed toward the front and rear portions of the other tortoise's shell.

Biting.-In Gopherus berlandleri biting occurs in both courtship and combat. I have never observed biting in the combat of 9. polyphemus. it is reported in the combat of G. agassizi (Camp, 1916; Woodbury and Hardy, 1948; Grant, 1946). During courtship males of G. berlandieri bite the females on the head, front legs, and the front edge of the carapace. As courtship proceeds biting becomes increasingly confined to the anterior edge of the female's carapace. Biting also occurs In combat in this species. Both males may bite one another very forcibly, although I have never seen injuries. During the courtship of _G. Polyphemus the males bite the head and front feet of the females, but confine most of the shell biting to the female's gular projection and the anterior carapace edge is not biten. Camp (1916) and Woodbury and Hardy (1948) report biting in both courtship and combat of G. aqassizi. Eglis (1963) reports that a courting male Homous areolatus vigorously bit the head of a female. I have seen female Geochelone elephantopus produce serious wounds by biting exposed areas of Gopherus polyphemus, although the biting was not in a courtship or combat context. Beltz (1954) reports






28

that a male. bgae dentiulat attacked a large opherus aqasslzl by biting and ramming its shell and limbs. Biting in tortoise courtship is

not universal and in at least one species, Geochelone travancorica, courtship occurs without any biting (Auffenberg, 1964).

Rauuia.-Ramming of the female by the male during courtship is

known for all tortoise species whose courtship is well reported. In the courtship of Gopherus berlandlerI the male rams the female's sides more frequently than other parts of her shell. In combat ramming tends to be confined to the front ends of the shell of the opposing males. Ramming in combat often develops Into a pushing contest Instead of an exchange of blows. In either case one male attempts to place his gular projection under the plastron of the other and overturn him. This effort results in a distinctive upward thrust at the end of each ramming movement. This upward arc is missing from courtship ramming in G. berlandler. The ramming motion begins from a position in which the tortoise is standing on all four legs. The movement is initiated by a slight backward rocking movement on all four legs, immediately followed by a sudden forward thrust in which the head and, to a lesser extent, the front legs are withdrawn. The withdrawal of the front legs gives a decided downward angle to the forward thrust. In combat ramming the front legs are extended fully on impact, thus providing the characteristic upward arc. In courtship ramming the front legs do not appear to be withdrawn; there is no upward arc at the end of the forward thrust; the ramming movement is on a more horizontal plane. In Gopherus, and other species, ramming has the function of Immobillizing the female In courtship and the male in combat.








Watson (1962) reported that the ramming of female Testudo reecE lbera by the male had a distinct rhytlhmic quality that I have not observed in any species of Gooherus. Ditmars (1910) reported a peculiar lateral bumping in the courtship of Geochelone elephantopus. This report did not clearly describe how the lateral bumping was accomplished.

Locomotion.-During certain phases of courtship in Gopherus

berlandigeri, G. polyphemus, and G. agassizi the female appears to avoid a face to face confrontation with the male by retreating. Her path of retreat is usually circular or semicircular, since the male charges, bites, and rams the female first from one side and then the other, always attempting to meet her head on. The result in berlandlerl is a circular movement of the courting pair with the male moving in an outer, larger circle and the female in an inner, smaller circle. In combat between some male G. berlandleri a similar circular retreat pattern arises when one male, the less aggressive of the two, attempts to avoid the more aggressive male and thus occupies the inner circle. In the courtship of G. polyphemus the female avoids the male by a similar retreat pattern.

In Homopus the male circles the female to ram or bite her, but she does not avoid him by turning away in the circular path described for Gopherus, but would "agitatedly skitter aside" (Eglis, 1962).

Vocal lzation.-Vocallization has been reported for several tortoise species during courtship or copulation, but not during combat. Van Denburgh's (1914) account of vocalization in the combat of Geochelone elephantous has been questioned (Auffenberg, 1965). In Gopherus it has been described for G. berlandlerl by Householder (1950). Householder's description was based on a courtship between two tortoises he presumed








were desert tortoises, Gopheru sslzl. Woodbury (1952) later showed that the male of this pair was actually a Texas tortoise berlandierl. Campbell and Evans (1967) reported vocalization in oheru am aLi. but the vocalization was not In a courtship or combat context. Most reports of vocalization during breeding activities suggest that such sounds are a by-product of the effort expended in copulation. There is no indication that vocalization serves as an auditory signal. However, the males of Geochlne elhant)us bellow before copulation during the breeding season (Van Denburgh, 1914), and males of G. arbonar vocalize prior to copulation (Snedigar and Rokosky, 1950). This latter observation was made on what was presumed to be GeocheIgne dentlI lata. However, the photo in Snedigar and Rokosky's paper clearly shows that the tortoises were G. arbonari.

Presentaton.-A female facilitates successful fntremission and in higher vertebrates invites copulation by presentation, in Gophers berlanderl the female holds her body In a characteristic position and extrudes her cloaca. The female's stance is one with head and forelimbs withdrawn and rear limbs partially extended. In Gophrus olyhemus the presentation is similar but the female's rear legs seem to be extended more stiffly than in .. berlandier and she may pivot so that the rear of her shell is nearest the males head. I have never observed this in .. berlandler.









Table 2

Stages of Courtship observed in
Gopherus beriandlerl


Stage Male F I emale


Follows female and occasionally bobs head

increased vigor of head bobbing, rate of walking surpasses that of female


indifferent to male


Increases walking speed


Overtakes female, feet, carapace


bites her


Tries to avoid male, turns away from him, both describe a circular pattern


Rams female


Withdraws head and front
feet, rear feet remain extended


Initial mounting attempts


Remain still, or may attempt to walk away


Rams and bites If female tries to walk away


4. Coltion























Figure 9

Stages of courtship in Gopherus berlandlerl. A, trailing; 8, ramming; C, biting, D, mounting









0 3 8aV














COURTSHIP IN 0PHERUS BERLANDIERI


The field observations for courtship were made in Texas in Cameron County, near Brownsville, and in Webb County, near Laredo. My earliest observations of courtship were in June, and the latest in November. Some courtship was observed in outdoor enclosures at the Welder Wildlife Refuge near Sinton, San Particio County, Texas, and Gainesville, Alachua County, Florida. Twelve complete courtship sequences were observed in the field and approximately twelve incomplete performances (less than three of the four stages in Table 2) were observed in the field and among captive specimens.

Behavior preceding copulation can be treated in four stages (Table 2). Stage one is a relatively passive phase during which the female shows little active response to the male's presence, but during which she modulates the male's behavior. In the remaining stages the female's behavior is modulated by that of the male.

Stage one.-Courtship behavior begins with the male trailing a female (Fig. 9-A). Initially the male walks behind the female and his behavior is modulated by hers. This is shown by two major characteristics of the trailing phase; (1) whenever the female stops the male stops and, (2) the male often bobs his head in the female's direction. During the early portion of the trailing stage the male walks with his neck usually only partly extended. The female does not bob her head at any time during the trailing stage. During this initial stage of courtship the female's






































Figure 10
Sexual dlmorphism In Gherus berlgadlerl. Males (left) have a deep posterior plastral depression, thickened anal notch margins, and an elongate gular projection at the anterior end. The female's plastron (right) Is flat without thickened anal notch margins and has a shorter gular projection. The posterior ends of both tortoises are at the bottom of the p eiture.






36

behavioral role is largely one of Indifference. She normally grazes and "noses" at various items on the ground, displaying the same movements and activity as that observed for lone, unattended females. In some trailing the female makes one or more stops in the shade. During these stops the male appears to lose Interest, and may even graze. When the female resumes walking, the male assumes his previous behavior. These shade stops may be a temperature regulating behavior.

Late in the trailing stage, which may last from a few minutes to nearly an hour, the male shortens the distance between himself and the female. When he is about three feet directly behind the female he increases the frequency and vigor of head bobbing and when not bobbing holds his head in a high, arched position. His neck is inclined between 250 and 350 but the top of his head is parallel to the ground. At this point the female increases her walking speed, and ceases all grazing activity. This shift in the female's behavior marks the end of stage one.

Stage two.-The second stage of courtship marks the start of phase two, is more intense than the first stage, and begins when the male attempts to overtake the female and confront her face to face. The male overtakes the female and stops her by biting her head, front feet, the top, front edge of her carapace, and ramming her forcibly with his massive, elongate gular projection (Fig. 9-B, C; Fig. 10). The female first avoids the male; he consistently tries to establish a face to face position with her. The female turns away from the male, which results in both tortoises moving in a circular path of constantly diminishing diameter. The male continues to increase the Intensity of biting and ramming; finally the female withdraws her head and front legs but






37

continues to pivot her anterior end away from that of the male by driving with her rear feet. The male's biting tempo increases, but his head bobbing stops or loses any recognizable pattern. Biting of the female by the male is increasingly confined to the nuchal and anterior peripheral bones. The bites become very forceful, the male often grasping a portion of the female's shell in his mouth and alternately pushing and pulling her. The female now withdraws her head and front feet, leaving her rear feet extended. Her position is therefore an incline, with the rear of her shell highest. She no longer pivots and the male attempts to mount her. The stimulus or releaser for mounting behavior in the male seems to be the female's inclined position. Observations by Walter Auffenberg made near Laredo, Texas, suggest that the female selects the place where stage two and the subsequent stages occur. This is usually an area relatively free of underbrush.

Stage three.-Initial mounting attempts by the male may occur any place on the female's shell. If the initial mounting occurs at other than the rear of the female's shell, the male works his way to the rear with his front feet on the dorsal surface of the female's carapace, and his rear feet on the ground (Fig. 9-D).

Stage four.-None of the unions I observed lasted over ten minutes. They were usually terminated when the female walked out from under the male. Householder (1950) reported that a female of G. berlandlerl (he thought it was a female G. aqassizi) everted part of her cloaca which seemed to facilitate intromission by the male. This occurs in female Gopherus polyphemus and Eglis reported similar behavior in Ho us. I did not, however, observe this in G. berlandleri courtships. Each thrust by the male during copulation pushes the female forward. To compensate








for the female's change of position the male performs a series of hopsteps with his rear feet. if intromission occurs in a brushy area his rear legs become tangled in the grass, the hop-step is impeded, and copulation is interrupted. Thus the female's selection of an area relatively free of underbrush helps ensure successful coition.

From 7:00 until 8:00 p.m. I watched a pair trailing (Stage 1, Table 2) on the northeast side of one of the lomas (dunes) characteristic of

the Jackass Prairie, near Brownsville, Texas. The male was bobbing his head in a series between 3 and 36 bobs. The male stopped when the female stopped. At two different times during this sequence the Individuals were facing one another at approximately 1100; the male's head was in the female's field of vision, but she did not reciprocate with head bobs. Just before dark (7:30 p.m.) the female stopped in an open area

with scattered clumps of grass (Bouteloua) and prickly pear (Opuntia); she headed Into a clump of grass and came to a halt. The male stopped both walking and head bobbing. The female withdrew head and feet. The male's head protruded about li inches. Both had remained in these positions when I left the area at 8:00 p.m.

I returned at 5:15 a.m. The tortoises were in the same place and in the same positions as when I left them. At 7:10 a.m. the male fully extended his neck at an angle of about 200 and immediately resumed bobbing in sequences averaging seven bobs. However, his head was not in the high arc I have observed in other courtships. By 7:27 a.m. neither tortoise had moved from the spots they had stopped earlier the previous night. Now the male began to hold his head in the high, arched position. At 7:35 a.m. the female started to walk and was followed Immediately by the male bobbing his head. By 7:40 a.m. the male skirted









the female on her right. She turned away from him counter-clockwise and he followed, still bobbing. He bit the anterior end of her shell and she withdrew her head and forefeet. By 7:45 a m. the female was no longer turning away from the male The male's bites were more forceful, he grasped, pushed and pulled the female. At 7:50 a.m. he mounted her, holding his mouth open during copulation. I heard no sounds from him, but both the wind direction and my distance of 30 yards from the pair may have dampened any vocalization. At 7:58 a.m. the female walked out from under the male He followed her for five or six feet and made a few slow, low intensity head bobs. The female moved into a pallet, the male walked away.









TABLE 3

Stages in the Courtship of Gopherus polyphemus
(after Auffenberg, 1966)


Stage Male Female


I. Walks in circle and bobs head

Approaches male

2. Bobs head violently with
approach of female

3. Bites female on legs and shell
especially gular projection

4. Moves backward in semicircle; stretches hind legs

First mounting attempts (usually
unsuccessful) followed by more
biting

Radius of semicircle becomes so small that female begins to pivot
1800 about a central point

5. First successful mountings and
finally coition















COURTSHIP IN OTHER GOPHERUS SPECIES


The courtship of Goherus polyphemus has been described by Auffenberg (1966) and differs in several respects from that of G. berlandleri. In no instance have I seen female G. berlandleri make an initial approach to male G. berlandleri as occurs in G. polyphemus (Stage 2, Table 3). Head bobbing is faster in polyphemus than in berlandlerl (Fig. 8). Ramming of the female by the male is similar in both species, but the biting (Stage 3, Table 3) differs in that G. berlandleri males have not been observed to bite the gular projection of G. berlandlerI females. The courtship is similar in the two species in that during the biting phase of courtship females of both G. polyphemus and G. berlandleri move backward away from the male in a circular path. (Stage 2, Table 2; Stage 4, Table 3).

The only reference to courtship or combat behavior in G.

flavamarainatus is by Legler and Webb (1961). They observed that males initially assume an aggressive role and that the females did not approach the male as in the early part of courtship in G. polyphgus. Male and female G. flavomrainatus have a tendency to push or crowd tortoises against an object such as a fence post or rock. In one instance a female G. flavomarginatus crushed a female and on another occasion a male G. polyphemus against a fence post so forcibly that the shell of the G. polyphemus was fractured in several places (Francis L. Rose, personal communication).








Courtship observations on 0. aassizi are numerous but are lacking in detail. Householder (1950) provided a good account of what was assumed to be successful courtship in G. agassilzi. However, the tortoise pair involved were later identified by Woodbury (1952) as a male G. berlandieri and a female G. aqasslzi. Woodbury and Hardy (1948) described a courtship (?) of G. agassizi, but omitted the kind of detail useful in comparing this behavior to that in other species. This is true of most of the published accounts of courtship in tortoises Our knowledge now demands that meticulous observations be recorded of all of the behavior involved in courtship or combat Tortoise behavior varies in significant but often extremely subtle ways as does tortoise morphology.















COMBAT IN GOPHERUS BERLANDIERI


Combat between males begins before the breeding season and drops off sharply in frequency before the breeding season is over. The following observations are based on three complete and four partial combat sequences seen in the field and on many partial sequences observed among captive tortoises. I have seen combat between captive males kept in an outdoor pen as early as March and combat has been observed in the field as late as July.

True combat in Gopherus berlandlerl occurs only between males. I have seen only one instance of antagonistic behavior between adult females which involved only pushing.

Two aggressive males approach each other and ram. One combatant attempts to overturn the other. One male walks toward another or both move toward each other. Their heads may be motionless or bobbing vigorously. At first ramming is mutual. This type of combat in which both tortoises are initially aggressive will be called Type One combat. Another kind of combat, Type Two, occurs between males if one is clearly dominant and the other is not aggressive. The dominant tortoise rams and bites the subordinate one in a series of movements similar to those in Stage Two of courtship. The dominant male rams and even bites the subordinate male on the front feet, head, and the same part of the shell he does on the female during courtship. The subordinate male avoids the aggressive male by pivoting from the aggressor in the same circular






44

turning pattern of the female described in courtship. The dominant male was never observed to attempt to mount a subordinate male. This type of combat ends when the subordinate male escapes to a pallet or withdraws all appendages and remains still. Biting is not a major component of Type One combat, in contrast to Type Two combat.

Type One combat occurs when neither male becomes subordinate. Both males engage in ramming and biting, and both attempt to overturn the other with their gular projections. Dominance is apparently established when one overturns the other, or when one flees the combat area after a ramming and pushing contest. Evidence of the combat often remains on the ground in the form of a large circular area in which the soil has been tramped by the feet and plastra of the combatants. Similar areas are left after stage two of courtship (Table 2). At the end of Type Two combat the victorious male holds his head at a higher level than that of the defeated male. If combat terminates by one tortoise fleeing, the loser will retreat with its head extended directly in front, and the winner pursues with its head inclined about 300.

The following account of Type Two combat is taken from my field notes taken at Sinton, Texas, 3 August, 1965.

Lake Camp at 10:00 a.m.: I observed fighting between two males of the 34 tortoises kept in the yard. A large male (male one) walked rapidly from a clear place on the lawn to a fence 10 feet away where there were three females and a small male (male two). Male one immediately rammed the smaller male and blocked his access to the females. The male tortoises bobbed their heads when facing one another. The smaller male two was passive at first and was turned completely twice around by the rival. After twice being turned around the smaller male






45

bobbed and lunged at the larger one. After a short pause during which both were inactive male two walked toward the center of the lawn away from male one. Male one followed immediately and bobbed his head in the direction of male two. The following of male two by male one was exactly like trailing in courtship (Fig. 9-A). Male two "played" the female role as he nosed items on the ground and slowed his walk. The "chase" covered about 30 yards and lasted until 10:20 a.m. Then male one overtook and gently bit the anterior end of male two's carapace. Male two promptly withdrew all appendages. At 10:23 a.m. the chase began anew, male one tried to overtake male two and bite his head. At 10:25 a.m. male two found and entered a grassy depression and remained there. Male one stood behind male two and bobbed his head. Movements by male two caused male one to ram the exposed rear of male two's shell. At 10:30 a.m. male one still stood behind male two who remained in the depression. Male one continued to bob his head In the direction of male two at Irregular intervals. After a short while male one walked away.

Mr. Kenneth G. Mentocha and Robert L. Snavely, then students at the Rob and Bessie Welder Wildlife Foundation of Sinton, San Patricio County, Texas gave an excellent report of type one combat. The combat occurred Just southwest of Sinton, Texas.

24 July, 1965, 6:40 p.m.---2 gopher tortoises in "combat." Heard noise in brush about 20' away. Sounded somewhat like a Javelina moving through the brush. Both tortoises were between a Xanthoxylem and a Celtis pallid, pushing each other with the gular projections. After about I minute they backed off and began to breath heavily as if they had been at the "fight" a long while and were catching their breath. After about 30 seconds they again begin the combat. While in close contact, the smaller tortoise continually bit the front portion of the carapace of "Stubby."* "Stubby" seemed to be the stronger of the two


*"'Stubby"---The larger of the 2 tortoises. Had no claws on left front foot, but a large callous.








and pushed the smaller one around quite a bit. He (Stubby) would put his gular projection beneath the plastron (mostly in the front) and begin to lift the other in an apparent attempt to turn it over. Three or four times, when the smaller tortoise appeared as if it would be turned over, it would place its forelimbs over and around the back of those of "Stubby" and appear to be holding on in order not to be turned over. Stubby pushed the other tortoise backward several times but most often into a bush and could not turn it over due to the resistance of the bush.

About 7:10 p.m. the two finally came into an open area during the combat ("Stubby" pushed the other tortoise into the open), and during a time of "combat" when both had their head withdrawn and were pushing on one another, I flipped the smaller tortoise onto its back. "Stubby" then came up to the other tortoise, which was trying to turn back over and began to bite In on the side (edge) of the shell and left hind foot. The smaller tortoise turned back over onto its feet and "Stubby" immediately placed its gular projection under the side of the shell of the smaller tortoise and turned it onto its back again. This time the smaller tortoise lay motionless and "Stubby" Just looked at it. After about 30 seconds "Stubby" turned around and walked off. Both were picked up in order to determine sex. This was about 7:15 a.m. A circle (on the ground) of about 6' in diameter showed evidence of much scratching which must have occurred prior to the above observations.

In a large outdoor pen in Gainesville, Florida, combat has been observed as early as March 12. In Brownsville, Cameron County, Texas,

local residents also reported tortoise combats as early as March.














COMBAT IN OTHER GOPHERUS


Less is known of combat in other species of Gopherus than of courtship. Woodbury and Hardy (1948), and Grant (1936) reported that males of . aqcassilzi charge one another with heads retracted. The contest consists of attempts by one tortoise to overturn the other using the gular projection (Fig. 10) as both a ram and a lever. Miller (1932) reported that hatchling G. aqassizl would ram and lunge at each other, or at an extended human finger.

Legler and Webb (1961) describe fighting in G. flavMrglnatus; I have observed no combat between captives of this species.

Carr (1952) reports on fights between males and females of Gpherus golyphemus. I have seen ramming between a captive male and a female of this species, and observed one particularly ambitious, moderate-sized, malformed, male G. polyphmus repeatedly ram subadult Geochelone eleophantous and an adult G. pardalls, both of which were at least 20 pounds heavier than the G. polyphemus. Some information on combat in G. Dolyphemus was gained by observing confrontations between male Gopherus polvyphemus in the laboratory.

In these experiments each of six adult male tortoises was marked and kept in rectangular indoor pens. The room housing the pens was automatically kept on a nine and one-half hour day throughout the experimental period (February 1, 1965-April 1, 1965). Air temperature for the entire test period varied from 760 F. to 780 F.






48

For each trial two tortoises were placed diagonally from each other in one of the rectangular pens. Prior to each trial I wet the tortoises with water, a procedure which seemed to stimulate the tortoises. In field situations I have observed that tortoises were more active after a rain. A blind so placed as to hide me from the tortoises produced no observable change in the tortoise's behavior and its use was discontinued. The distances between tortoises when head bobbing first occurred was recorded. Each trial lasted until the tortoises failed to react to each other. Portions of the trials were recorded on 180 feet of motion picture film. The analysis of these interactions including the filmed portions follows.

The responses between two male G. polyphemus consist of initial

responses, locomotion, head bobbing, mutual smelling, and establishment of a dominant-subordinate relationship. I considered a tortoise highly motivated if it reacted to the presence of another tortoise immediately upon start of the trial and poorly motivated if it delayed longer than two or three minutes before reacting to the other tortoise. Contact was

defined as the moment two tortoises came together closely enough to touch as a result of directed locomotion by one or both of the reptiles.

Initial responses.-Poorly motivated Individuals spent three to four minutes smelling the substrate of the pen or old feces before mctually pointing their head in the direction of the other tortoise. Highly motivated tortoises immediately began to walk in the direction of the other tortoise. Tortoises with an intruder placed in their pens either remained still, immediately proceeded toward the intruder, or in a few cases turned into a corner.

Locomotion.-I defined locomotion as directed, that influenced by another tortoise, and nondirected, that apparently not influenced by






49

another tortoise. In directed locomotion of a highly motivated tortoise the neck is fully extended and walking Is rapid. Nondirected locomotion is slower and the neck is only partially extended.

Head bobbing.-Eglis (1962) classified head bobbing in Goherus

as dirolent. This is the typical head movement performed when smelling substrate or food. In meetings between two tortoises bobbing usually occurs first when the tortoises are about two and one-half feet apart.

The function of head bobbing in G. polyphemus is not clear. The fact that a tortoise is always directed toward another tortoise when bobbing occurs suggests that a visual cue may be involved. However a highly motivated tortoise continues to walk toward another tortoise whether or not reciprocal bobbing or directed locomotion occurs. A poorly motivated tortoise may not continue bobbing or walking in the direction of another tortoise if no reciprocal head bobbing or directed locomotion occurs.

In as much as the behavioral functions of head bobbing are largely unknown, adjectives such as "contentment," "enthusiastic," "nod of friendship" used in conjunction with head bobbing can serve only to make ambiguous otherwise informative reports (Nichols, 1953).

Mutual smelling.-At contact the vertical bobs of both tortoises assume a large lateral component and finally lose any recognizable movement pattern. The head and feet of both tortoises are the objects of smelling. The vertical bobs associated with these smelling movements are often interrupted by a lateral wiping motion directed to the surface of one of the forelegs. After one to two minutes of mutual smelling, one of the tortoises becomes more active in all its movements than the other.






50
Dominance-subordinance.-Domlnance relationships are clearly demonstrated by the relative postures of the tortoises. The dominant tortoise supports its weight on all four of its extended legs. He may walk around the other tortoise, stopping often to smell his rear legs. The submissive tortoise holds his head lower to the ground, with his neck partially extended. If the dominant tortoise continues investigative activity, the submissive tortoise positions himself at an angle of approximately 45o to the dominant tortoise and he maneuvers so that one side (either side) is always presented to the front of the dominant individual. Such maneuvering is done with the rear legs and, pivoting on the anterior portion of the plastron, the front legs continue to be withdrawn. After one to two minutes of this behavior the more active dominant Individual will turn away, apparently no longer interested in the other tortoise. Dominance can be demonstrated by placing a small amount of food in the pen with the two tortoises; the dominant tortoise inhibits feeding by a subordinate tortoise.

The males of several tortoise and turtle species engage in shell ramming during combat and for immobilizing the female prior to copulation (Auffenberg, 1964; Brumwel, 1940; Taylor, 1933; Nikolskil, 1915; Hamilton, 1944). Carr (1952) reported ramming between males of G. polyphemus; however, I observed none in these tests. However, observations made in the spring and summer included ramming between males of G. polvohemus, and males of G. polyphemus ramming males of Geochelone elephantopus and G. pardalis. Ramming in Gopherus berlandleri has been discussed earlier in this paper.

The presence of a distinct dominant-submissive relationship in Gopherus suggests that such behavior is species-specific. It is






51

conceivable that in meetings between males of Gopherus polyphemus (or females in the nonbreeding season), noncombative recognition of dominance would result in the subordinate tortoise leaving the area of the dominant individual. However, these particular experiments failed to show that a given G. polyphemus is dominant to any intruder introduced into its "home" pen. Instead there was a marked tendency for certain individuals to be dominant both in their own pens and in those of other tortoises. Gene Gourly at the University of Florida is currently completing a study of orientation and territoriality in G. polyphemus.














BEHAVIORAL ELEMENTS COMMON TO
COURTSHIP AND COMBAT

In both courtship and combat one member of the pair assumes an

aggressive role. In courtship it is usually the male. Courtship ends only when the female is immobilized for intromission. Aggressive behavior in Type One combat of Gopherus berlandlerl continues until one tortoise is overturned or pushed away. And in Type Two combat until the nonaggressive member of the pair escapes by fleeing or retreating to a shelter. In some instances a dominance relationship may be established without fighting, as shown by the experiments using male Gepherus polyphemus. In G. berlandleri dominance is established by behavior common to both courtship and combat, particularly Type Two combat. This behavior includes head position, shell ramming, and biting.

When two male G. berlandierl approach one another, or when a male

approaches a nonaggressive male, their respective head positions indicate if the confrontation will be Type One or Type Two combat. An aggressive tortoise holds his head higher and extends it further outward than a nonaggressive tortoise. The subsequent behavior of the nonaggressive male or female Is often seemingly unrelated to either combat or courtship.

In meetings between two aggressive tortoises both hold their heads high, and each reacts aggressively. During the ramming and biting in stage two of courtship the male tortoise's head is held higher than that of the female, who finally retracts her head partially or fully Just prior to and during presentation.






53

Shell ramming in courtship results In immobilization of the female. In males of G. berlandlerl the shell ramming of Type One combat ultimately determines dominance. In Type One combat the ramming movement has an upward arc at the end of the forward thrust, to overturn the other tortoise. The upward arc is absent In ramming in courtship and Type Two combat of G. berlandlerl.

In Type Two combat of G. berlandlerl all four legs of the dominant male are extended and his head is nearly fully extended and arched. The subordinate male withdraws his feet and fully or partially withdraws his head which is thus lower than that of the dominant male. Similarly, in courtship the female finally withdraws her head and front feet, but leaves her rear feet extended. Both the subordinate male in Type Two combat and the subordinate female in courtship support at least part of their weight on the plastron, while the dominant male stands on all four legs.















EXPERIMENTS


The preceding observations were based largely on field work. To

more clearly evaluate the field worklaboratory experiments were designed to find cues used by Gopherus berlandlerl to distinguish sex in its own species. Experimental data were analyzed with nonparametric statistics because I doubt that they conform to all the assumptions underlying the appropriate parametric tests, particularly the interval measurement scale. With this in mind I used the Kruskal-Wallis one-way analysis of variance, and in one case the Chi Square test, to determine the homogeneity of groups of date, and the Fisher-Exact Probability test to compare medians within groups of data.

The Oen Square Tests

These experiments were designed to detect a differential investigative response by male and female tortoises to other male and female tortoises and controls. The test tortoise was placed in the large open square box and male and female tortoises were placed individually into the small removable cage as a stimulus. Controls were performed with the removable cage empty.

The tortoises were tested when the chin glands were actively secreting (July 21, 1966; November 5, 1966) and when they were inactive (April 11, 1967; June 1, 1967). The data for tortoises with active chin glands










Table 4


Results of the Open Square Experiments


Test Males responding to: Male Females responding to: Female Condition Totals Totals
Males Females Control Males Females Control



Chin glands 47.5(6) 142.5(10) 63.0(6) 253.0 71.5(5) 56 5(5) 59.0(9) 187.0
act ive





Chin glands 59.0(5) 33.0(5) 27.5(5) 119.5 38.0(5) 46-0(5) 39.0(5) 123.0
Inactive


The scores are the totals of ranked raw scores used in the Kruskal-Wallis analysis The numbers in parentheses are replications for the Indicated trials, each lasting 24


of variance.
hours.








represent the responses of 22 different males and 15 different females used for a total of 41 trials, each lasting 24 hours.

The trials for tortoises with Inactive glands were performed on 15 different males and females for a total of 30 trials lasting 24 hours each. The trials were distributed equally between two open square testing boxes. The scores for the open square tests are shown in Table

4. The analysis of these scores provides the following results:

(1) When the chin glands were active males responded differentially to males, females, and controls (p(.15S); the difference in response to males and females was not significant; however males tended to respond more to other tortoises (males and females collectively) than to controls

(p=.20).

(2) Females showed a strong differential response (p<.05) to the stimuli of males, females, and controls and reacted more to males than to controls or females (p=.05).

(3) When the chin glands were inactive the males showed a strong differential response (p <.05) to the three stimuli. This response was greater for other males than for females or controls (p-.10).

(4) Females showed no differential response when their chin glands were inactive.

(5) Both male and female tortoises made more responses to the stimuli when their glands were active then when they were inactive (p <.01).

The Closed Square Tests

Response to Live Animals.-Experiments using live test animals were designed to test if male and female tortoises could distinguish sex on the basis of movements of other male and female tortoises. Five









different males and females were used for a total of fifteen trials. The live tortoises used as stimuli were confined in a sealed glass aquarium which was placed in the small, removable cage (Fig. 3). Thus a response to the animals would have to be based on something other than olfactory cues. Controls were the empty aquarium in the removable cage. While the tortoises were being tested (July, 1967) their chin glands were secreting. Each trial lasted four hours. Experienced gained from the open square experiments showed that most (90%) of the responses recorded during a trial were made during the first four hours.

Response to Preserved Test Animals.-The closed square experiments using formalin-preserved tortoises as a stimulus were designed to detect any differential response by male and female tortoises to the sight of other tortoises. The sealed aquarium eliminated odor as a cue and tortoises preserved in life-like stances eliminated movement as a possible stimulus. This experiment therefore tested external morphology as a clue to sex determination. The tortoises were tested when their chin glands were active (July and August, 1967). Each trial lasted four hours and the controls were empty aquaria. The test tortoises consisted of five different males and females used for a total of fifteen trials.

Table 5 shows the scores of the closed square experiments. Analysis of these scores provide the following results:

(I) The males showed no significant ability to differentiate between males, females, and controls (Table 5) when movement or external morphology were the stimuli (Fig. 10).

(2) Females reacted more (p <.15) to moving tortoises than to the controls but on the basis of external morphology did not distinguish between males, females, or controls.











Table 5


Results of the Closed Square Experiments


Test Males responding to: Male Females responding to: Female Condition Tota ls Totals Males Females Control Males Females Controls



Live Tort.

in Test Cage 38.0(5) 47.0(5) 32.0(5) 117.0 51.0(5) 45(5) 20(5) 116.0





Preserved

tort. In 43.0(5) 37.o(5) 68.o(7) 148.0 54.5(6) 54.5(6) 41.0(5) 150.0 Test Cage



The scores are the totals of ranked raw scores used in the Kruskal-Wallis analysis of variance. The numbers In parentheses are replications for the Indicated trials, each lasting four hours.











Table 6


Results of the Cloaca Scent Tests


Responses of Males to Cloaca Responses to Females to

Scent of: Scent of:


Males Females Controls Males Females Controls


66.5(6) 51.0(6) 53.5(6) 86.5(6) 44.5(6) 40.0(6)



The scores are the totals of ranked raw scores used in the Kruskal-Wallis analysis of variance. The members in parentheses are replications for the Indicated trials, each lasting twenty-four hours.








The Cloaca Scent Tests

The ability of male and female tortoises to distinguish sex on the basis of cloaca odor was evaluated by comparing their responses to cotton swabs which had been smeared with cloacal material from both sexes. Controls were clean cotton swabs. Jar posltlons were adjusted so that male, female, and control swabs appeared an equal number of times at each station (Table 6). The jars were washed after each trial. The tests were performed from October 15, 1966 through November 10, 1966. Each trial lasted twenty-four hours. A total of 20 females and 22 males were used.

Male Gopherus berlandlerl were unable to distinguish between male, female, and control swabs. The females did not respond equally to all three test items (p

Hormone injections

Efforts to facilitate tortoise reactions in laboratory situations and to observe possible effects of hormones on the chin glands were performed by subcutaneous injections of various hormones.

On March 11, 1967 three pairs of healthy male tortoises of approximately the same size were selected, one member of each pair was injected with 20 mg. of testosterone phenylacetate. The dosage was extrapolated from Evan's (1951) work on Chrysemys (then Pseudemys) scripta troosti on the basis of carapace length. One pair remained in the outdoor pen, another pair was put in an indoor pen on a 24-hour day, and the third pair put in an Indoor pen on a five-hour day. By 14 March the chin glands






61

of the experimental tortoise on the five-hour day were enlarged and secreting. The glands of the experimental tortoise kept In the outdoor pen produced some secretion and were somewhat enlarged. The chin glands of the experimental tortoise kept on the 24-hour day, and those of all the controls did not produce a secretion or become enlarged. In the outdoor pen some pushing not clearly definable as Type One or Type Two combat was initiated by two injected males with some of the noninjected tortoises.

These results indicate that in the male the chin gland's activity is influenced by the concentration of the male sex hormone and changes In day length.

Injections of 25 mg. of progesterone In adult females and 20 mg. of testosterone in adult males when the glands of both sexes were active (July, 1967) resulted in no observable change in the condition of their chin glands or behavior. Injections of 50 mg. of thyroxine in males and females seemed to stimulate appetite.

Investigative activity on the part of males and to a lesser extent females can be elicited when small amounts of both testosterone phenylacetate or progesterone are placed in front of the tortoise's nose.













DISCUSSION


Mating in Gopherus berlandlerl is divided into four major stages (Table 2) during which sexual discrimination is accomplished. Little is known of sex and species discrimination in other tortoises. Several species are sympatric, and closely related sympatric animal populations are often segregated by species specific mating behavior. Mating behavior under any circumstances involves sexual discrimination. Mating behavior in sympatric populations is therefore made even more complex by the additional problem of species identification.

The behavioral elements (Table 2) comprising the courtship of Gopherus berlandleri differ in two major respects from those of G. polyphemus (Table 3); the initiation of courtship the female of G. polyphemus and the different regions of the female's shell bitten by the male. In the early stages of courtship females of G. polyphemus approach males, a behavior I have never observed in female G. berlandlerl. However to state that the female G. berlandleri plays a passive role in courtship is incorrect. The experimental results (Table 4) show that for G. berlandlerl: (1) females respond more to males than to females or controls during the breeding season (approximately that period when the chin glands are actively secreting) and, (2) only females can distinguish males from females by cloaca scent.

Observations of courtship in G. polyphemus are based on tortoises from populations typical in that Individuals construct burrows and








maintain more or less well-defined territories. (Auffenberg, 1966-a; in press). The Individual members of such populations occupy more or less mutually exclusive areas in which contact with other tortoises is probably greatly restricted. Individuals must leave their normal activity area in search of other tortoises during the breeding season. Under these circumstances females would be more aggressive in seeking males than would females from nomadic populations. An active response by females to threat and courtship displays of males has been postulated as one evolutionary result of territorial behavior (Bastock, 1967).

All the a. berlandlerl were from nomadic populations of the

Jackass Prairie near Brownsville, Texas. These Individuals have relatively large activity ranges and females often meet males in their daily movements. The experimental evidence suggests that the ability of female G. berlandlerl to detect males by confrontations (Table 4), cloacal scent (Table 6), and her tendency to be attracted to moving tortoises of either sex (Table 5) ensure her discovery by males during the breeding season. The differences in aggressiveness between female G. berlandierl and female G. polynhemus can be explained in terms of the different ecology of the two species.

The males of Gopherus polvhemus and G. berlandleri consistently bite different areas of the female's shell during courtship. Hale G. berlandleri bite the female's head, front legs, and, most consistently, the upper part of the female's carapace in the region of the nuchal bone. This biting becomes increasingly forceful during courtship. Biting by males of G. polvyohemus differs in two important respects from that in .. berlandlerl in that it is concentrated on the female's gular proJection and is less forceful. I interpret the biting of the female by






64

the male to be a highly specific behavior of considerable importance in the courtship of the two species. Differences in the courtship behavior could well stem from isolating mechanisms resulting from Pleistocene sympatry. That the courtship of the two groups is mutually exclusive, possibly as a result of this sympatry (Fig. 1) is supported by: (1) Hybridization between species of the agassizi group that produced living offspring (Householder, 1950; Woodbury, 1952); (2) On several occasions I placed males and females of G. berlandleri, G. agasszl and G. Polyphemus together both in indoor and outdoor pens and the only courtship observed was between males and females of the same species, or between members of the aassi group (G. aqassizI and I. berlandlerl).

The laboratory experiments show that Gogherus berlandlerl consistently makes heterosexual preferences only when chin glands are actively secreting (Table 4). The chin gland's secretion consisted of aromatic compounds, the compositions and concentrations of which are different in males and females (Rose, Weaver, Drotman, ms). In males the activity of this gland is probably controlled, in part, by testosterone level and day length.

Sexual discrimination in G. berlandlerl may be shared by both sexes. The female's ability to distinguish males from females by cloacal scent is one such discriminatory ability. Exactly how a male determines if a tortoise is a female is not known, but the experiments show that males cannot recognize females by cloacal scent, external morphology, or movement. This suggests that sexual discrimination by the male rests in part, with the secretion of the chin glands. That the glands enable the male to distinguish the sexes is suggested by a comparison of the results of the open square experiments with respect to chin gland activity








(Table 4). The males react to females when chin glands are active in both sexes, and to males when the glands are inactive in both sexes. Females react to males when the glands of both sexes are active, and do not discriminate when glands are inactive. These data and the field observations of courtship and combat suggest a means by which sexual discrimination is accomplished in q. berlandleri. Attribute to the female's glands substances A and B, and to the male's glands substance A. These symbols represent the sexual differences in the chemical composition of the gland's secretion. During the latter part of the trailing phase of courtship (Stage 1, Table 2) or the first part of phase two (Stage 2, Table 2)---the stimulus of scents A and B signals the male that the other tortoise is a female. Since a stage resembling trailing (Stage 1, Table 2) occurs in Type Two combat between males, sexual identification probably occurs in stage two when close contact occurs. The female's ability to detect the male by cloaca scent (hence also perhaps by feces), and her positive response to moving tortoiselike objects provide an orientation mechanism by which she is discovered by males. In G. berlndleri intromission is accomplished only if the female cooperates by presenting, behavior not seen in Type two combat between males, and by partially extruding her cloaca toward that of the mounted male. Failure of the female to distinguish another tortoise as a male by cloacal scent results in her failure to present, thus preventing intromission. Sexual discrimination may be made independently in both sexes in stage two of courtship.

Initial meetings of potential breeding pairs are due to, (1) a
biased attraction of females for moving tortoise-like objects and, (2) a probable high but random investigative behavior of males. Sexual discrimination does not occur until stage two of courtship.








Males respond more to males than to females when chin glands are inactive (Table 4). This conclusion is supported by: (1) Combat has been observed between captive adult males when the glands were inactive, and among juveniles when the glands are presumably Inoperative (at least no reaction is observable and the glands are not seasonally enlarged); the only female combat I have observed was between two subadults; (2) most of the combat observations in the Brownsville area and from captive specimens from Brownsville, are from relatively early in the reproductive season when the glands are not active; (3) the chin glands of individuals in the Brownsville populations were not enlarged until late June or early July, corresponding roughly with the first widespread observations of courtship; (4) I have never observed adult females ram or otherwise behave aggressively toward adult males. These observations suggest that a male recognizes a female only when the chin glands of both are active. Aggressive behavior is characteristic only of males. Therefore Type One combat occurs only between males. If another tortoise assumes a subordinate role, it is a nonaggressive adult male, a Juvenile of either sex, or an adult female. if mating behavior then occurs it will be courtship if the proper chin gland odor (substance A and 8) is present and Type Two combat if the proper chin

gland odor is not present.

I have never observed males present, or any males mounting males in any combat in G. berlandlerl. In stage two of courtship the female presents and mounting occurs. This suggests that, (1) presentation may release mounting and copulatory behavior and that, (2) the identification of a tortoise as a female by a male may also be partly dependent on such a releaser. In this case the chin gland secretion would not








be the only means of sexual identification in the species; behavior would also serve as a means of sex identification.

Head movements are known to be visual signals in Geochelone

carbonaria and G. denticulata (Auffenberg, 1965). I do not believe that a visual sex or species-specific signal is the primary role of head bobbing in G. berlandlerl because it is most frequently performed by the male during the trailing stage of courtship when he is out of the female's visual field, males often bob at females in pallets when the male is also out of the female's visual field, and males may scarcely bob at all, and then erratically, when confronting a female. Head bobbing in Gopherus berlandleri, and probably the other species of Gooherus is primarily an olfactory movement. In Gopherus head bobbing has species-specific differences (Fig. 8), but no known visual discriminatory function. This suggests that in Gopherus head bobbing is in an early stage of emancipation to a visual signal function from a movement attending olfaction. This is supported in part by information gained watching a male captive G. aqasslzI who bobbed at a female G. berlandlerl when she turned her head toward him. Therefore bobbing in all species of opherus may not have the same role. The type of head movements used by the South American Geochelone in species discrimination is the same as that used by them in olfaction: The head movements as visual signals in Geochelone are derived directly from the head movements associated with olfaction.
While head bobbing may be insignificant as a visual signal in Gopherus, the angle a tortoise inclines its head reflects a dominant or subordinate status and may serve as a visual indicator to other tortoises. In combat dominant males of Gopherus berlandleri incline








their heads higher than do subordinate males. Dominant males of G. polyphemus keep their heads higher than subordinate males during confrontations. In courtship the head of an aroused male of G. berlandieri is fully outstretched and inclined in a high arch. A sexually aroused male would therefore automatically display a dominant head position and intimidate other males less highly motivated sexually.

The question of dominance is central to successful courtship or combat behavior. The significance of the similar behavior used to establish dominance in both courtship and combat, particularly as seen in G. berlandlerl, is that it indicates that the behavioral units of courtship are derived from those of combat. One of the major differences between the courtship and combat of G. berlandlerl and G. polyphemus is that while neither species engages in interspecific courtship with the other in captive situations, males of G. berlandlerl and both sexes of G. polyphemus have been observed to participate in Interspecific combat with individuals of the other species of Gopherus as well as with Individuals of species of other genera. Hatchlings of Gopherus aassizi (Miller, 1932) ram one another, and I have observed young g. polyphemus up to a year of age do the same. I have seen no attempts to assume a copulatory position in species of Gopherus this young. Combative behavior In adults may arise from many situations, such as limited food, space, or shelter. Species-specific courtship behavior apparently arises in tortoises only when sympatry with other turtle or tortoise species confuses species identification. Tortoise species with a long history of allopatry are notorious for their lack of species discrimination during the breeding season. Footballs, rocks, or any tortolse-resembling object appeal equally to the nondiscriminating maletortolse.






69

in a much larger sense courtship is a block of behavioral elements which seems to have been displaced or emancipated from phylogenetically older functions as a form of combat, specifically, In this case, Type Two combat. Displacement activity is abundantly reported for many groups of animals. Basically it consists of a behavior which is emancipated from one set of causal factors to another set (Blest, 1963; Tinbergen, 1952). Displacement activity largely consists of comfort movements and appears to arise in the presence of intense conflicting drives (Hess, 1965). The behavior of female tortoises in the trailing stage of courtship (Stage 1, Table 2) or of a nonaggressive male in the early stages of Type Two combat appears to be an example of displacement activity. In courtship, in particular, grazing by the female during the trailing stage could well be a comfort movement. Head bobbing in courtship or combat is another example of displacement behavior since its origin is probably in movements to facilitate olfaction. At least in one instance head bobbing as a visual signal has been demonstrated to be derived from head bobbing associated with simple olfaction

(Auffenberg, 1965).














BIBLIOGRAPHY


Agassiz, A. 1857. Contributions to the natural history of the United
States of America, Vol. 1. Boston: Little Brown and Co.

Auffenberg, V. 1964. A redefinition of the fossil tortoise genus
Stylem Leidy. J. Paleo., 38(2): 316-324.

1964. Notes on the courtship of the land tortoise Geochelone
travancorica (Boulenger). J. Bombay Nat. Hist. Soc., 61(2):
247-253.

.. 1965. Sex and species discrimination in two sympatric South
American tortoises. Copela (3): 335-342.

1966a. On the courtship of Gopherus alvohemus. Herp. 22
(3): 113-117.
1966b. The carpus of land tortoises (Testudininae). Bull.
Fla. State Mus. 10(5): 159-191.

Tortoise behavior. BSCS pamphlet. In press.

and W. B. Weaver, Jr. The ecological behavior of Gooherus
berlandleri in southeastern Texas. Bull. Fla. State Mus. In press.

Bastock, Margaret. 1967. Courtship: an ethological study Aldine
Publishing Co., Chicago. pp. 220.

Beltz, R. E. 1954. Miscellaneous observation on captive Testudininae.
Herp. 10: 45-47.
Blest, A. D. 1963. The concept of ritualization. In: Current problems in animal behavior. W. H. Thorpe and 0. L. Zanwill (ed),
Cambridge Univ. Press., pp. 102-124.

Brumwell, M. J. 1940. Notes on courtship of the turtle, Terranen
ornate. Trans. Kansas Acad. Scl., 43: 391-392.

Camp, C. L. 1916. Notes on the local distribution and habits of amphiblans and reptiles of southeastern California in the vicinity of the Turtle Mountains. Univ. Calif. Publ. Zool., 12(17): 503-544.
Campbell, Howard W. and William E. Evans. 1967. Sound production in
two species of tortoises. Harp., 23(3): 204-209.








Carpenter, C. R. 1962. Societies of monkeys and apes. In: Primate
social behavior. Charles H. Southwich (ed), D. Van Nostrand
Company, Inc. pp. 24-51.

Car, Archie. 1952. Handbook of turtles. New York: Comstock Publication.

DeSola, R. 1930. The Liebesplel of Testudo vandenburghi, a new name
for the mid-Albemarle Island Galapagos tortoise. Copela (3): 7980.

Ditmars, R. L. 1910. Reptiles of the world. New York: Sturgis
Walton Company.

Doumerque, F. 1899. Essal sur la Faune erpetologigue de I'Oranle.
Soc. Geogr. Arch. Ovan, 19: 197-260, 501-502.

Egits, A. 1962. Tortoise behavior: a taxonomic adjunct. Herp. 18
(1): 1-8.

1963. Nesting of a parrot-beaked tortoise. Herp. 19(1):

Evans, L. T. 1951. Effects of male hormone upon the tail of the slider
turtle Pseudemys scripta troostil. Science 114(2959): 277-279.

Fitzsimons, V. 1935. Notes on a collection of reptiles and amphibians
made in the southern Kalahari, Bushmanland and Great and Little
Namagua land. Annals Transvaal Mus., 15: 519-550.

Grant, Chapman 1936. The southwestern desert tortoise, Gopherus
agassizII. Zoologica 21(4): 225-229.

1946. Data and field notes on the desert tortoise (Gopherus
agassizi). Trans. San Diego Soc. Nat. Hist. 10: 399-402.
1960. Differentiation of the southwestern tortoises (genus
Gopherus) with notes on their habits. Trans. San Diego Soc. Nat.
Hist. 12: 441-448.

and C. R. DeSola. 1934. Antillean tortoises and terrapins:
distribution, status and habits of Testudo and Pseudemys. Copela
(2): 73-79.

Hamilton, Rodgers D. 1944. Notes on the mating and migration of
berlandlers turtle. Copela, 1942 (1): 62.

Hay, Oliver P. 1908. The fossil turtles of North America. Spec.
Publ. Carneg. Inst., Wash., 75: 268 pp.

Heller, Edmund. 1903. Papers from the Hopkins Stanford Galapagos
Expedition 1898-99, XVI. Reptilla. Proc. Wash. Acad. Sdl., 5:
39-98.

Hess, E. H. 1965. Ethology: an approach toward the complete analysis
of behavior. In: Readings in animal behavior. Holt, Rinehart
and Winston.







Householder, V. H. 1950. Courtship and coition of the desert tortoise.
Harp., 6: 11.

Legler, J. M. and R. C. Webb. 1961. Remarks on a collection of Bolson
tortoises, Gopherus flavomarginatus. Herp. 17(1): 26-37.

Miller, Loyce. 1932. Notes on the desert tortoise (Testudo aqassizil).
Trans. San Diego Soc. Nat. Hist. 7: 187-208.

Mykytowycz, R. 1965. Further observations on the territorial functions
and histology of the submandibular (chin) cutaneous glands in the
rabbit. Animal Behav. 13(4): 440-412.

Nichols, Una G. 1953. Habits of the desert tortoise, Goo-herus aqassizil.
Herp. 9(2): 65-69.

.. .. 1957. The desert tortoise in captivity. Herp. 13: 141-144.
NikolskiI, A. M. 1915. Fauna of Russia and adjacent countries, Vol. 1,
Reptiles. Zool. Mus. Russ. Cad. Scl., pp. 1-532.

Rose, Francis L., W. G. Weaver, Jr., and Robert B. Drotman. Preliminary
analyses of the chin glands of Gopherus. (ms).
Rose, Walter. 1950. The Reptiles and Amphibians of Southern Africa.
Procter: Cape Town.

Siegel, Sidney. 1956. Nonparametrlc statistics for the behavioral
sciences. McGraw-Hill. 1

Smith, H. and S. 0. Brown. 1946. A hitherto neglected Integumentary
gland in the Texan tortoise. Proc. Texas Acad. Sol. 30: 45.
Snedigar, R. and Rokosky, E. J. 1950. Courtship and egg laying of
captive Testudo dticulata. Copela (1): 46-48.

Taylor, E. H. 1933. Observations on the courtship of turtles. Univ.
Kansas Sl. Bull. 21: 269-271.

Tinbergen, N. 1952. Derived activities; their causation, biological
significance, origin and emancipation during evolution. Quart.
Rev. Blo. 27: 1-32.

Van Denburgh, J. 1914. The gigantic land tortoises of the Galapagos
archipelago. Proc. Calif. Acad. Sdl., 2(1): 203-374.

Watson, George E. 1962. Notes on copulation and distribution of
Aegean land tortoises. Copela (2): 317-321.

Wermuth, H. and R. Mertens. 1961. Schildkroten, Krokodile, Bruckenechson. Veb Gustav Fischer Verlag, Jena.

Woodbury, A. M. 1952. Hybrids of Gopherus berlandlerl and G. agaassizi.
Herp., 8: 33-36.

Woodbury, A. M. and Hardy R. 1948. Studies of the desert tortoise
Gooherus agassizl. Ecol. Monogr. 18: 145-200.













BIOGRAPHICAL SKETCH


William Glenn Weaver, Jr.,was born August 14, 1936, at Tampa,

Florida. In August, 1954, he was graduated from Robert E. Lee High School in Jacksonville, Florida. From 1954 until 1958 he served in the United States Air Force. In 1959 he enrolled in Jacksonville University, Jacksonville, Florida, where he received the degree of Bachelor of Science in June, 1962. He enrolled in the Graduate School of the University of Florida in June, 1962, and worked as a graduate assistant in the Florida State Museum until June, 1964, when he received the degree of Master of Science. From June, 1964, until the present time he has pursued his work toward the degree of Doctor of Philosophy. He served as a teaching assistant in biology from September, 1965, until December, 1966, and as an Interim instructor in biology for the University of Florida from January, 1967, until August, 1967. He is presently an Instructor at Santa Fe Junior College in Gainesville, Florida.
William Glenn Weaver, Jr.,is married to the former Margarette Annette Plaster and is the father of two children. He is a member of the American Society of Ichthyologists and Herpetologists, The Herpetologists League, American Association for the Advancement of Science, and Phi Siga.













This dissertation was prepared under the direction of the chairman of the candidate's supervisory comnunittee and has been approved by all members of that committee. It was submitted to the Dean of the College of Arts and Sciences and to the Graduate Council, and was approved as partial fulfillment of the requirements for the degree of Doctor of Philosophy.


December 19, 1967







Dean, College/ Art d Sc I fences




Dean, Graduate School




Supervisory Committee:



Cha i an / i




Full Text
Table 5
Results of the Closed Square Experiments
Test
Males responding to:
Male
Fema1es
responding to:
Female
Condition
Males
Females
Control
Totals
Males
Females
Controls
Totals
Live Tort.
in Test Cage
38.0(5)
*+7.0(5)
32.0(5)
117.0
51.0(5)
45(5)
20(5)
116.0
Preserved
tort, in
*+3-0(5)
37.0(5)
68.0(7)
148.0
54.5(6)
54.5(6)
41.0(5)
150.0
Test Cage
The scores are the totals of ranked raw scores used In the Kruskal-Wal1 Is analysis of variance.
The numbers In parentheses are replications for the indicated trials, each lasting four hours
vn
CO


38
for the female's change of position the male performs a series of hop-
steps with his rear feet, if intromission occurs in a brushy area his
rear legs become tangled in the grass, the hop-step is impeded, and copu
lation is interrupted. Thus the female's selection of an area relatively
free of underbrush helps ensure successful coition.
From 7:00 until 8:00 p.m. I watched a pair trailing (Stage 1, Table
2) on the northeast side of one of the lomas (dunes) characteristic of
the Jackass Prairie, near Brownsville, Texas. The male was bobbing his
head in a series between 3 and 36 bobs. The male stopped when the fe
male stopped. At two different times during this sequence the individ
uals were facing one another at approximately 110; the male's head was
In the female's field of vision, but she did not reciprocate with head
bobs. Just before dark (7:30 p.m.) the female stopped in an open area
with scattered clumps of grass (Bouteloua) and prickly pear (Opuntla):
she headed Into a clump of grass and came to a halt. The male stopped
both walking and head bobbing. The female withdrew head and feet. The
male's head protruded about l£ inches. Both had remained in these
positions when l left the area at 8:00 p.m.
I returned at 5:15 a.m. The tortoises were in the same place and
In the same positions as when I left them. At 7:10 a.m. the male fully
extended his neck at an angle of about 20 and immediately resumed
bobbing in sequences averaging seven bobs. However, his head was not
In the high arc I have observed in other courtships. By 7:27 a.m.
neither tortoise had moved from the spots they had stopped earlier the
previous night. Now the male began to hold his head in the high, arched
position. At 7:35 a.m. the female started to walk and was followed
immediately by the male bobbing his head. By 7:40 a.m. the male skirted


37
continues to pivot her anterior end away from that of the male by driving
with her rear feet. The male's biting tempo Increases, but his head
bobbing stops or loses any recognizable pattern. Biting of the female
by the male is Increasingly confined to the nuchal and anterior peripheral
bones. The bites become very forceful, the male often grasping a portion
of the female's shell in his mouth and alternately pushing and pulling
her. The female now withdraws her head and front feet, leaving her rear
feet extended. Her position is therefore an incline, with the rear of
her shell highest. She no longer pivots and the male attempts to mount
her. The stimulus or releaser for mounting behavior in the male seems
to be the female's Inclined position. Observations by Walter Auffenberg
made near Laredo, Texas, suggest that the female selects the place where
stage two and the subsequent stages occur. This is usually an area re
latively free of underbrush.
Stage three.-Initial mounting attempts by the male may occur any
place on the female's shell. If the Initial mounting occurs at other
than the rear of the female's shell, the male works his way to the rear
with his front feet on the dorsal surface of the female's carapace,
and his rear feet on the ground (Fig. 9-D).
Stage four.-None of the unions I observed lasted over ten minutes.
They were usually terminated when the female walked out from under the
male. Householder (1950) reported that a female of G,. berlandieri (he
thought it was a female £. agasslzi) everted part of her cloaca which
seemed to facilitate Intromission by the male. This occurs in female
Gopherus polyphemus and Eglis reported similar behavior in Homopus. I
did not, however, observe this in £. berlandieri courtships. Each thrust
by the male during copulation pushes the female forward. To compensate


48
For each trial two tortoises were placed diagonally from each other
in one of the rectangular pens. Prior to each trial I wet the tortoises
with water, a procedure which seemed to stimulate the tortoises. In
field situations I have observed that tortoises were more active after a
rain. A blind so placed as to hide me from the tortoises produced no ob
servable change In the tortoise's behavior and its use was discontinued.
The distances between tortoises when head bobbing first occurred was re
corded. Each trial lasted until the tortoises failed to react to each
other. Portions of the trials were recorded on 180 feet of motion pic
ture film. The analysis of these interactions including the filmed
portions follows.
The responses between two male (S. polyphemus consist of initial
responses, locomotion, head bobbing, mutual smelling, and establishment
of a dominant-subordinate relationship. I considered a tortoise highly
motivated if It reacted to the presence of another tortoise Immediately
upon start of the trial and poorly motivated if it delayed longer than
two or three minutes before reacting to the other tortoise. Contact was
defined as the moment two tortoises came together closely enough to
touch as a result of directed locomotion by one or both of the reptiles.
Initial responses.-Poorly motivated individuals spent three to four
minutes smelling the substrate of the pen or old feces before actually
pointing their head in the direction of the other tortoise. Highly moti
vated tortoises immediately began to walk in the direction of the other
tortoise. Tortoises with an Intruder placed in their pens either remained
still, immediately proceeded toward the Intruder, or In a few cases
turned into a corner.
Locomotion.-I defined locomotion as directed, that influenced by
another tortoise, and nondlrected, that apparently not influenced by


DISCUSSION
Mating In Gopherus berlandierl is divided Into four major stages
(Table 2) during which sexual discrimination Is accomplished. Little
Is known of sex and species discrimination In other tortoises. Several
species are sympatrlc, and closely related sympatric animal populations
are often segregated by species specific mating behavior. Mating be
havior under any circumstances involves sexual discrimination. Mating
behavior In sympatrlc populations Is therefore made even more complex
by the additional problem of species Identification.
The behavioral elements (Table 2) comprising the courtship of
Gopherus berlandierl differ in two major respects from those of G.
polyphemus (Table 3); the initiation of courtship the female of G.
poiyphemus and the different regions of the female's shell bitten by the
male. In the early stages of courtship females of (5. polyphemus
approach males, a behavior I have never observed in female (5. berlandierl.
However to state that the female G. berlandieri plays a passive role In
courtship is incorrect. The experimental results (Table 4) show that
for J3. berlandieri: (1) females respond more to males than to females
or controls during the breeding season (approximately that period when
the chin glands are actively secreting) and, (2) only females can dis
tinguish males from females by cloaca scent.
Observations of courtship in (5. polyphemus are based on tortoises
from populations typical In that Individuals construct burrows and
62


BEHAVIORAL ELEMENTS COMMON TO
COURTSHIP AND COMBAT
In both courtship and combat one member of the pair assumes an
aggressive role. In courtship it Is usually the male. Courtship ends
only when the female Is immobilized for intromission. Aggressive behav
ior In Type One combat of Gopherus berlandieri continues until one tor
toise is overturned or pushed away. And in Type Two combat until the
nonaggressive member of the pair escapes by fleeing or retreating to a
shelter. In some Instances a dominance relationship may be established
without fighting, as shown by the experiments using male Gopherus
Polyphemus. In (3. berlandieri dominance is established by behavior
common to both courtship and combat, particularly Type Two combat. This
behavior Includes head position, shell ramming, and biting.
When two male G_. berlandieri approach one another, or when a male
approaches a nonaggressive male, their respective head positions indicate
if the confrontation will be Type One or Type Two combat. An aggressive
tortoise holds his head higher and extends it further outward than a
nonaggressive tortoise. The subsequent behavior of the nonaggressive
male or female Is often seemingly unrelated to either combat or courtship.
In meetings between two aggressive tortoises both hold their heads
high, and each reacts aggressively. During the ramming and biting In
stage two of courtship the male tortoise's head is held higher than that
of the female, who finally retracts her head partially or fully just
prior to and during presentation.
52


COURTSHIP IN GOPHERUS BERLANDIERI
The field observations for courtship were made In Texas In Cameron
County, near Brownsville, and In Webb County, near Laredo. My earliest
observations of courtship were in June, and the latest In November.
Some courtship was observed In outdoor enclosures at the Welder Wildlife
Refuge near Sinton, San Partido County, Texas, and Gainesville, Alachua
County, Florida. Twelve complete courtship sequences were observed In
the field and approximately twelve Incomplete performances (less than
three of the four stages In Table 2) were observed In the field and
among captive specimens.
Behavior preceding copulation can be treated in four stages (Table
2). Stage one Is a relatively passive phase during which the female
shows little active response to the male's presence, but during which she
modulates the male's behavior. In the remaining stages the female's
behavior Is modulated by that of the male.
Stage one.-Courtship behavior begins with the male trailing a female
(Fig. 9"A). Initially the male walks behind the female and his behavior
Is modulated by hers. This Is shown by two major characteristics of the
trailing phase; (1) whenever the female stops the male stops and, (2) the
male often bobs his head In the female's direction. During the early
portion of the trailing stage the male walks with his neck usually only
partly extended. The female does not bob her head at any time during the
trailing stage. During this initial stage of courtship the female's
34


10
experimental tortoise; C, vacuum tube sensor; D, wire leads from
sensor to digital counter. The pen, B, is five feet in length and
width and 18 inches high.


INTRODUCTION
The acuity of sex and species discrimination in mammals and birds
is largely a function of ecological sympatry with other closely related
species and therefore is a behavioral Isolating mechanism. Recent work
on fossil and living tortoises suggests that courtship behavior In tor
toise species with a long history of sympatry Is also more complex and
discriminating than In allopatric species. A high discriminatory ability
may persist In tortoise species currently allopatric, but only In those
species pairs whose fossil record reveals a prior sympatry. Sympatrlc
species which morphologically are prevented from Interbreeding, such as
Geochelone travaneorica and G. elegans. do not have a high discriminatory
ability (Auffenberg, 1964).
The four extant species of the genus Gopherus are allopatric. How
ever, fossil specimens from northern Mexico and the western United States
show that certain species of the genus were sympatrlc during the Pleisto
cene (Fig. 1). Thus the extant species provide an opportunity to Investi
gate the influence of prior sympatry (Pleistocene) on the courtship behav
ior of species which have since become allopatric. The objectives of this
investigation are:
(1) to describe and analyze the courtship and combat behavior of
one of these species-Gopherus beriandlerl;
(2) to compare this behavior with that known for the other living
species of Gopherus:
1


Figure 6
Histological section of the chin gland of a male Gopherus berlandleri.
This section, made In November, 1966, shows collecting duct lined
with epithelial cells. The mass In the duct Is composed of cells that
have built up their products and have been discharged into the lumen
as Is typical of holocrine glands. The base of thegland Is at the
bottom of the photograph.


65
(Table 4). The males react to females when chin glands are active in
both sexes, and to males when the glands are inactive in both sexes.
Females react to males when the glands of both sexes are active, and do
not discriminate when glands are inactive. These data and the field
observations of courtship and combat suggest a means by which sexual
discrimination is accomplished in G,. berlandier!. Attribute to the
female's glands substances A and 8, and to the male's glands substance
A. These symbols represent the sexual differences in the chemical com
position of the gland's secretion. During the latter part of the
trailing phase of courtship (Stage 1, Table 2) or the first part of
phase two (Stage 2, Table 2)-the stimulus of scents A and B signals
the male that the other tortoise is a female. Since a stage resembling
trailing (Stage 1, Table 2) occurs in Type Two combat between males,
sexual identification probably occurs In stage two when close contact
occurs. The female's ability to detect the male by cloaca scent (hence
also perhaps by feces), and her positive response to moving tortoise
like objects provide an orientation mechanism by which she is discovered
by males. In G,. berlandlerl intromission Is accomplished only if the
female cooperates by presenting, behavior not seen in Type two combat
between males, and by partially extruding her cloaca toward that of the
mounted male. Failure of the female to distinguish another tortoise as
a male by cloacal scent results in her failure to present, thus pre
venting intromission. Sexual discrimination may be made Independently
in both sexes In stage two of courtship.
Initial meetings of potential breeding pairs are due to, (1) a
biased attraction of females for moving tortolse-1Ike objects and, (2)
a probable high but random investigative behavior of males. Sexual
discrimination does not occur until stage two of courtship.


ACKNOWLEDGEMENTS
I was assisted in this investigation by a grant and facilities from
the Welder Wildlife Foundation at Sinton, Texas. National Science
Foundation grant (NSF GB 3738) to Dr. Walter Auffenberg partially
supported some of the field and laboratory work. The Florida State
Museum and the University of Florida Graduate School also provided
support. Francis L. Rose generously provided Information and materials
for certain sections of this paper. The drawn figures were prepared by
Mr. Nell Payne and Dr. Walter Auffenberg.
I am particularly Indebted to Dr. Walter Auffenberg whose active
interest, unique biological perspective, and personal example guided me
throughout the investigation.
li


42
Courtship observations on J3. aqassizl are numerous but are lacking
in detail. Householder (1950) provided a good account of what was
assumed to be successful courtship in JG. agasslzi. However, the tortoise
pair involved were later Identified by Woodbury (1952) as a male G.
berlandieri and a female G_. agasslzi. Woodbury and Hardy (1948) de
scribed a courtship (?) of G,. aqassizl but omitted the kind of detail
useful in comparing this behavior to that in other species. This is true
of most of the published accounts of courtship In tortoises Our knowl
edge now demands that meticulous observations be recorded of all of the
behavior involved In courtship or combat Tortoise behavior varies in
significant but often extremely subtle ways as does tortoise morphology.


TABLE OF CONTENTS
ACKNOWLEDGEMENTS
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS
INTERRELATIONSHIPS OF BEHAVIOR AND ECOLOGY
METHODS
BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS IN COURTSHIP AND COMBAT. .
COURTSHIP IN GOPHERUS BERLANDIERI
COURTSHIP IN OTHER GOPHERUS SPECIES
COMBAT IN GOPHERUS BERLANDIERI
COMBAT IN OTHER GOPHERUS
BEHAVIORAL ELEMENTS COMMON TO COURTSHIP AND COMBAT
EXPERIMENTS
The Open Square Tests
The Closed Square Tests
The Cloaca Scent Tests
Hormone Injections
DISCUSSION
BIBLIOGRAPHY
Page
II
Iv
v
1
5
6
8
15
34
41
43
47
52
54
54
56
60
60
62
70
ill


26
actively toward the male. Obviously trailing will eventually bring the
male and female together physically, but the significance of Its rltual-
llke cadence In the early part of courtship In 6. berlandler! Is unknown.
Eglls (1963) reported an Instance of a male Homopus areolatus
following a female In a peculiar manner: The male's front feet were limp
and the entire locomotion was accomplished by pushing motions of the rear
feet.
Courtship position.-A distinct courtship stance has been reported
only for Homopus areolatus. However In confrontations between captive
male Gopherus polyphemus a stance or positioning of bodies occurs con
sistently enough to be considered In this behavioral category. In
Homopus the male faces the female with their shells at a 90 angle
(Eglls, 1963). This positioning Is accomplished by the male's rushing
around first one side and then the other of the female. In meetings
between male Gopherus polyphemus a similar position may also be achieved.
The position Is achieved by the more aggressive specimen, but seems more
dependent on the timidity of the nonaggressIve male than on strenuous
efforts by the aggressive male as In Homopus areolatus. No similar
positioning has been reported for other species of Gopherus: nor have I
observed any.
01 fact Ion.-Ma1e tortoises appear to smell various areas of females
or other males In all the courtship and combat encounters observed, and
In those reported In detail In the literature. The movement associated
with olfaction In Gopherus Is the head bob. However the head bobbing
observed In most courtship or combat situations differs in minor but
consistent ways from those observed when food or feces are being examined.
These later head movements In Gopherus have a predominant forward motion.


Figure 1
Ranges of Pleistocene and Recent Gopherus species Solid colors represent ranges of extant spe
cies. Horizontal lines represent Pleistocene range of the polyphemus group; vertical lines re
present the Pleistocene range of aqassizi group. Squares show probable area of overlap.


67
be the only means of sexual Identification In the species; behavior
would also serve as a means of sex Identification.
Head movements are known to be visual signals In Geochelone
carbonaria and _G. dentIculata (Auffenberg, 1965). I do not believe that
a visual sex or species-spec IfIc signal Is the primary role of head
bobbing In (5. berlandlerl because It Is most frequently performed by
the male during the trailing stage of courtship when he Is out of the
female's visual field, males often bob at females In pallets when the
male Is also out of the female's visual field, and males may scarcely
bob at all, and then erratically, when confronting a female. Head
bobbing In Gopherus berlandlerl. and probably the other species of
Gopherus Is primarily an olfactory movement. In Gopherus head bobbing
has species-specific differences (Fig. 8), but no known visual discrimi
natory function. This suggests that In Gopherus head bobbing Is In an
early stage of emancipation to a visual signal function from a movement
attending olfaction. This Is supported In part by Information gained
watching a male captive G_. agassIzl who bobbed at a female G.. berlandlerl
when she turned her head toward him. Therefore bobbing In all species
of Gopherus may not have the same role. The type of head movements used
by the South American Geochelone In species discrimination Is the same
as that used by them In olfaction: The head movements as visual signals
In Geochelone are derived directly from the head movements associated
with olfaction.
While head bobbing may be Insignificant as a visual signal In
Gopherus. the angle a tortoise Inclines Its head reflects a dominant
or subordinate status and may serve as a visual Indicator to other
tortoises. In combat dominant males of Gopherus berlandlerl Incline


20
Table 1
Behavioral Elements in Tortoise Courtship and Combat
Head bobbing Geochelone travaneorica (Auffenberg, 1964)
GL carbonaria (Auffenberg, 1965; Snedlgar and Rokosky,
1950)
G. denticulate (Auffenberg, 1965)
Gopherus agasslzl (Nichols, 1957; Woodbury and Hardy,
1948)
_G. berlandlerl (Householder, 1950)
£. f1avomarglnatus (Legler and Webb, 1961)
_G. polyphemus (Auffenberg, 1966)
Trailing Geochelone carbonaria (Snedlgar and Rokosky, 1950)
elephantopus (Watson, 1963)
G. pardalis (Watson, 1962)
Gopherus agasslzl (Nichols, 1957)
Gi. berlandlerl (Hamilton, 1944)
J. f 1 avomarglnatus (Legler and Webb, 1961)
G,. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglis, 1963)
Courtship position
Homopus areolatus (Eglls, 1962)
Smelling Geochelone carbonaria (Auffenberg, 1965)
G.. dentIculata (Auffenberg, 1965)
Gopherus agasslzl (Camp, C. L., 1916)


Carpenter, C. R. 1962. Societies of monkeys and apes. In: Primate
social behavior. Charles H. Southwlch (ed), 0. Van Nostrand
Company, Inc. pp. 24-51.
Car, Archie. 1952. Handbook of turtles. New York: Comstock Publi
cation.
DeSola, R. 1930. The Llebesplel of Testudo vandenburghl. a new name
for the mid-Albemarle Island Galapagos tortoise. Copela (3): 79"
80.
Dltmars, R. L. 1910. Reptiles of the world. New York: Sturgis
Walton Company.
Doumerque, F. 1899. Essal sur la Faune erpetologlgue de l'Oranle.
Soc. Geogr. Arch. Ovan, 19: 197-260, 501-502.
Eglls, A. 1962. Tortoise behavior: a taxonomic adjunct. Herp. 18
(1): 1-8.
1963. Nesting of a parrot-beaked tortoise. Herp. 19(1):
6(j-68.
Evans, L. T. 1951. Effects of male hormone upon the tall of the slider
turtle Pseudemys scrlpta troost 11. Science 114(2959): 277-279.
Fltzslmons, V. 1935. Notes on a collection of reptiles and amphibians
made In the southern Kalahari, Buskmanland and Great and Little
Namagua land. Annals Transvaal Mus., 15: 519550.
Grant, Chapman 1936. The southwestern desert tortoise, Gopherus
agassIzl1. Zoologlca 21(4): 225-229.
1946. Data and field notes on the desert tortoise (Gopherus
agasslzl). Trans. San Diego Soc. Nat. Hist. 10: 399"402.
___________ I960. Differentiation of the southwestern tortoises (genus
Gopherus) with notes on their habits. Trans. San Diego Soc. Nat.
Hist. 12: 441-448.
and C. R. DeSola. 1934. Antillean tortoises and terrapins:
distribution, status and habits of Testudo and Pseudemys. Copela
(2): 73-79.
Hamilton, Rodgers D. 1944. Notes on the mating and migration of
berlandlers turtle. Copela, 1942 (1): 62.
Hay, Oliver P. 1908. The fossil turtles of North America. Spec.
Publ. Carneg. Inst., Wash., 75: 268 pp.
Heller, Edmund. 1903. Papers from the Hopkins Stanford Galapagos
Expedition 1898-99, XVI. Reptil la. Proc. Wash. Acad. Scl., 5:
39-98.
Hess, E. H. 1965. Ethology: an approach toward the complete analysis
of behavior. In: Readings In animal behavior. Holt, Rinehart
and Winston.


29
Watson (1962) reported that the ramming of female Testudo graeca
Ibera by the male had a distinct rhythmic quality that I have not ob
served In any species of Gopherus. Dltmars (1910) reported a peculiar
lateral bumping In the courtship of Geochelone elephantopus. This report
did not clearly describe how the lateral bumping was accomplished.
Locomotion.-During certain phases of courtship in Gopherus
beriandierl. G. poiyphemus. and G_. agassizl the female appears to avoid
a face to face confrontation with the male by retreating. Her path of
retreat Is usually circular or semicircular, since the male charges,
bites, and rams the female first from one side and then the other, always
attempting to meet her head on. The result In JG. berlandleri Is a circu
lar movement of the courting pair with the male moving In an outer,
larger circle and the female In an Inner, smaller circle. In combat
between some male £. berlandieri a similar circular retreat pattern
arises when one male, the less aggressive of the two, attempts to avoid
the more aggressive male and thus occupies the Inner circle. In the
courtship of G.. polyphemus the female avoids the male by a similar re
treat pattern.
In Homopus the male circles the female to ram or bite her, but she
does not avoid him by turning away In the circular path described for
Gopherus. but would "agitatedly skitter aside" (Eglls, 1962).
VocalIzatIon.-VocalIzatlon has been reported for several tortoise
species during courtship or copulation, but not during combat.
Van Denburgh's (191*0 account of vocalization In the combat of Geochelone
elephantopus has been questioned (Auffenberg, 1965). In Gopherus It has
been described for G,. berlandieri by Householder (1950). Householder's
description was based on a courtship between two tortoises he presumed


36
behavioral role Is largely one of Indifference. She normally grazes and
"noses" at various items on the ground, displaying the same movements
and activity as that observed for lone, unattended females. In some
trailing the female makes one or more stops in the shade. During these
stops the male appears to lose Interest, and may even graze. When the
female resumes walking, the male assumes his previous behavior. These
shade stops may be a temperature regulating behavior.
Late in the trailing stage, which may last from a few minutes to
nearly an hour, the male shortens the distance between himself and the
female. When he Is about three feet directly behind the female he
increases the frequency and vigor of head bobbing and when not bobbing
holds his head in a high, arched position. His neck Is Inclined between
25 and 35 but the top of his head Is parallel to the ground. At this
point the female increases her walking speed, and ceases all grazing
activity. This shift In the female's behavior marks the end of stage
one.
Stage two.-The second stage of courtship marks the start of phase
two, Is more intense than the first stage, and begins when the male
attempts to overtake the female and confront her face to face. The
male overtakes the female and stops her by biting her head, front feet,
the top, front edge of her carapace, and ramming her forcibly with his
massive, elongate guiar projection (Fig. 9B, C; Fig. 10). The female
first avoids the male; he consistently tries to establish a face to face
position with her. The female turns away from the male, which results
In both tortoises moving In a circular path of constantly diminishing
diameter. The male continues to Increase the Intensity of biting and
ramming; finally the female withdraws her head and front legs but


51
conceivable that In meetings between males of Gopherus polyphemus (or
females In the nonbreeding season), noncombatlve recognition of dominance
would result In the subordinate tortoise leaving the area of the dominant
Individual. However, these particular experiments failed to show that
a given polyphemus is dominant to any Intruder Introduced into its
"home" pen. Instead there was a marked tendency for certain Individuals
to be dominant both In their own pens and In those of other tortoises.
Gene Gourly at the University of Florida Is currently completing a study
of orientation and territoriality in G,. polyphemus.


68
their heads higher than do subordinate males. Dominant males of G.
polyphemus keep their heads higher than subordinate males during con
frontations. In courtship the head of an aroused male of (3. berlandlerl
Is fully outstretched and Inclined In a high arch. A sexually aroused
male would therefore automatically display a dominant head position
and Intimidate other males less highly motivated sexually.
The question of dominance Is central to successful courtship or
combat behavior. The significance of the similar behavior used to
establish dominance In both courtship and combat, particularly as seen
In G. berlandlerl. Is that It Indicates that the behavioral units of
courtship are derived from those of combat. One of the major differences
between the courtship and combat of £. berlandlerl and JG. polyphemus Is
that while neither species engages In Interspecific courtship with the
other In captive situations, males of G. berlandlerl and both sexes of
£. polyphemus have been observed to participate In Interspecific combat
with Individuals of the other species of Gopherus as well as with In
dividuals of species of other genera. Hatchlings of Gopherus aqasslzl
(Miller, 1932) ram one another, and I have observed young G¡. polyphemus
up to a year of age do the same. I have seen no attempts to assume a
copulatory position In species of Gopherus this young. Combative
behavior In adults may arise from many situations, such as limited food,
space, or shelter. Specles-speclfIc courtship behavior apparently arises
In tortoises only when sympatry with other turtle or tortoise species
confuses species Identification. Tortoise species with a long history
of allopatry are notorious for their lack of species discrimination
during the breeding season. Footballs, rocks, or any tortoise-resembling
object appeal equally to the nondiscriminating maletortolse.


BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS
IN COURTSHIP AND COMBAT
As In other animals the reproductive activities of Gopherus
berlandleri are an Interaction of physiological and behavioral elements.
While the scope of this paper Is not to trace the major hormonal and
other chemical changes affecting courtship and combat behavior, one such
aspect In JG. berlandleri Is of such relevance that It Is Included here.
From the start of this Investigation In November, 1963, field obser
vations of (1. berlandleri suggested that breeding behavior In this spe
cies seemed to be correlated with the enlargement of a pair of large in-
tegumantary glands located ventrally and slightly medially on each man
dibular ramus (Fig. 5). Smith and Brown (1946) reported them as being
found only In G. berlandleri and Interpreted them as degenerate capsules
of connective tissue. However In his description of Gopherus berlandleri.
Agassiz (1857) compared the chin glands of this species with the similar
glands of G. polyphemus. Grant (1936) had already reported chin glands
in G,. agasslzl and lately Legler and Webb (1961) have described them In
G. flavomarglnatus. Among tortoises these glands are known only In spe
cies of Gopherus. Chin glands are well known In rabbits, where their
secretion Is used to mark territorial boundrles (Mykytowycz, 1965). In
Gopherus the glands are larger in males than in females, and larger In
G. agasslzl and (5. berlandleri than In G. polyphemus or G.
flavomarglnatus.
Auffenberg (1966a) found that female G. polyphemus rubbed their
15


Figure 10
Sexual dimorphism in Gooherus berlandlerl. Hales (left) have a deep
posterior pi astral depression, thickened anal notch margins, and an
elongate guiar projection at the anterior end. The female's plastron
(right) is flat without thickened anal notch margins and has a shorter
guiar projection. The posterior ends of both tortoises are at the
bottom of the picture.


53
Shell ramming In courtship results In Immobilization of the female.
In males of G.. berlandlerl the shell ramming of Type One combat ulti
mately determines dominance. In Type One combat the ramming movement
has an upward arc at the end of the forward thrust, to overturn the
other tortoise. The upward arc Is absent In ramming In courtship and
Type Two combat of (5. berlandlerl.
In Type Two combat of £. berlandieri all four legs of the dominant
male are extended and his head Is nearly fully extended and arched. The
subordinate male withdraws his feet and fully or partially withdraws his
head which Is thus lower than that of the dominant male. Similarly,
In courtship the female finally withdraws her head and front feet, but
leaves her rear feet extended. Both the subordinate male In Type Two
combat and the subordinate female In courtship support at least part
of their weight on the plastron, while the dominant male stands on all
four legs.


INTERRELATIONSHIPS OF BEHAVIOR AND
ECOLOGY IN GOPHERUS
The ecology and habits of only two species of Gopherus are reason
ably well known. Populations of G. agasslzi were studied In Utah by
Woodbury and Hardy (19^8), and £. berlandlerl has been studied in south
eastern Texas (Auffenberg and Weaver, In press). Additional studies are
In progress on G_. polyphemus.
Specimens of Gopherus berlandlerl have no permanent dally retreat as
do those of £. polyphemus. G. f lavomarglnatus. and some G,. agasslzi.
Over most of the range of G,. berlandlerl each individual occupies a pallet
which is little more than a sloping ramp rarely deep enough to lower the
anterior edge of the shell below the surface. The deeper end of older
pallets may be sufficiently overhanging to cover the entire shell. This
Is the normal shelter on the clayey soils throughout most of the species'
range. On more sandy soils some individuals dig a burrow to which they
return each day for most of their lives.
All the available evidence on tortoise activity indicates that
there is a positive correlation between shelter type and extent of activ
ity range. Where JJ. berlandlerl do not dig burrows they are largely no
madic. However burrow inhabiting individuals maintain a restricted activ
ity range (Auffenberg and Weaver, in press).
The range of Gopherus agasslzi is ecologically more variable than
that of the other living species of Gopherus. Consequently populations of
this species display considerable variation In ecologically related
6


COURTSHIP AND COMBAT BEHAVIOR
IN GOPHERUS BERLAND1ERI
By
WILLIAM GLENN WEAVER, JR.
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
December, 1967

ACKNOWLEDGEMENTS
I was assisted in this investigation by a grant and facilities from
the Welder Wildlife Foundation at Sinton, Texas. National Science
Foundation grant (NSF GB 3738) to Dr. Walter Auffenberg partially
supported some of the field and laboratory work. The Florida State
Museum and the University of Florida Graduate School also provided
support. Francis L. Rose generously provided Information and materials
for certain sections of this paper. The drawn figures were prepared by
Mr. Nell Payne and Dr. Walter Auffenberg.
I am particularly Indebted to Dr. Walter Auffenberg whose active
interest, unique biological perspective, and personal example guided me
throughout the investigation.
li

TABLE OF CONTENTS
ACKNOWLEDGEMENTS
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS
INTERRELATIONSHIPS OF BEHAVIOR AND ECOLOGY
METHODS
BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS IN COURTSHIP AND COMBAT. .
COURTSHIP IN GOPHERUS BERLANDIERI
COURTSHIP IN OTHER GOPHERUS SPECIES
COMBAT IN GOPHERUS BERLANDIERI
COMBAT IN OTHER GOPHERUS
BEHAVIORAL ELEMENTS COMMON TO COURTSHIP AND COMBAT
EXPERIMENTS
The Open Square Tests
The Closed Square Tests
The Cloaca Scent Tests
Hormone Injections
DISCUSSION
BIBLIOGRAPHY
Page
II
Iv
v
1
5
6
8
15
34
41
43
47
52
54
54
56
60
60
62
70
ill

LIST OF TABLES
Page
1. Behavioral Elements In Tortoise Courtship and Combat 20
2. Stages of Courtship Observed In Gopherus berlandlerl. 31
3. Stages In the Courtship of Gopherus polyphemus 40
k. Results of the Open Square Experiments 55
5. Results of the Closed Square Experiments 58
6. Results of the Cloaca Scent Tests 59
Iv

LIST OF FIGURES
Page
1. Ranges of Pleistocene and Recent Gooherus Species 4
2. The Open Square Apparatus 10
3. The Closed Square Apparatus II
4. Scent Testing Chamber 12
5. External View of Actively Secreting Chin Glands of a Hale
Gooherus berlandlerl 13
6. Histological Section of the Chin Gland of a Hale
Gooherus berlandlerl 18
7. Diagrammatic Representation of the Protein Bands In the
Chin Gland Secretion of Gooherus Species 19
8. Action Patterns of Head Bobbing 23
9. Stages of Courtship In Gooherus berlandlerl 33
10. Sexual Dimorphism In Gooherus berlandlerl 35
v

INTRODUCTION
The acuity of sex and species discrimination in mammals and birds
is largely a function of ecological sympatry with other closely related
species and therefore is a behavioral Isolating mechanism. Recent work
on fossil and living tortoises suggests that courtship behavior In tor
toise species with a long history of sympatry Is also more complex and
discriminating than In allopatric species. A high discriminatory ability
may persist In tortoise species currently allopatric, but only In those
species pairs whose fossil record reveals a prior sympatry. Sympatrlc
species which morphologically are prevented from Interbreeding, such as
Geochelone travaneorica and G. elegans. do not have a high discriminatory
ability (Auffenberg, 1964).
The four extant species of the genus Gopherus are allopatric. How
ever, fossil specimens from northern Mexico and the western United States
show that certain species of the genus were sympatrlc during the Pleisto
cene (Fig. 1). Thus the extant species provide an opportunity to Investi
gate the influence of prior sympatry (Pleistocene) on the courtship behav
ior of species which have since become allopatric. The objectives of this
investigation are:
(1) to describe and analyze the courtship and combat behavior of
one of these species-Gopherus beriandlerl;
(2) to compare this behavior with that known for the other living
species of Gopherus:
1

2
(3) to search for behavioral elements which have their origin In
mutually exclusive courtship patterns resulting from the prior
sympatry of Gopherus species.

Figure 1
Ranges of Pleistocene and Recent Gopherus species Solid colors represent ranges of extant spe
cies. Horizontal lines represent Pleistocene range of the polyphemus group; vertical lines re
present the Pleistocene range of aqassizi group. Squares show probable area of overlap.

% 0
d A,
G. berlandieri

FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS
The earliest known tortoises are represented by fossils from the
Eocene of Africa and North America. The earliest North American genus Is
Stylemys. known from the Eocene (Auffenberg, 1964). The genus Gopherus.
a descendant of Stylemys. Is represented In North America from the Ollgo-
cene to the Recent (Hay, 1908; Auffenberg, 1964). At least as early as
the Irvingtonlan stage of the Pleistocene Gopherus was already divided
Into Its two extant species groups; the polyphemus group, and the agasslzt
group (Auffenberg, 1966b). Gopherus polyphemus of the southeastern United
States and £. flavomarglnatus of north central Mexico comprise the
polyphemus group. Gopherus agasslzl of the southwestern United States
and northwestern Mexico, and G_. berlandierI of southeastern Texas and
northeastern Mexico comprise the agasslzl group (Fig. 1).
Wermuth and Mertens (1961) consider all living Gopherus populations
as subspecies of G_. polyphemus. Most workers (Auffenberg, 1966b; Carr,
1952; Grant, I960) treat each of the four populations as distinct species,
with which I concur.
5

INTERRELATIONSHIPS OF BEHAVIOR AND
ECOLOGY IN GOPHERUS
The ecology and habits of only two species of Gopherus are reason
ably well known. Populations of G. agasslzi were studied In Utah by
Woodbury and Hardy (19^8), and £. berlandlerl has been studied in south
eastern Texas (Auffenberg and Weaver, In press). Additional studies are
In progress on G_. polyphemus.
Specimens of Gopherus berlandlerl have no permanent dally retreat as
do those of £. polyphemus. G. f lavomarglnatus. and some G,. agasslzi.
Over most of the range of G,. berlandlerl each individual occupies a pallet
which is little more than a sloping ramp rarely deep enough to lower the
anterior edge of the shell below the surface. The deeper end of older
pallets may be sufficiently overhanging to cover the entire shell. This
Is the normal shelter on the clayey soils throughout most of the species'
range. On more sandy soils some individuals dig a burrow to which they
return each day for most of their lives.
All the available evidence on tortoise activity indicates that
there is a positive correlation between shelter type and extent of activ
ity range. Where JJ. berlandlerl do not dig burrows they are largely no
madic. However burrow inhabiting individuals maintain a restricted activ
ity range (Auffenberg and Weaver, in press).
The range of Gopherus agasslzi is ecologically more variable than
that of the other living species of Gopherus. Consequently populations of
this species display considerable variation In ecologically related
6

7
behavior (W. Auffenberg field notes, 1962, 1963, 1964). Individuals in
Sonora, Mexico, are nomadic all year, wandering in the dry arroyos of the
area. Their shelter consists of a hollow scraped into the base of the
arroyo wall. Further north, in the vicinity of Pima County, Arizona, the
tortoises hibernate in specific winter shelters which are usually enlarged
ground squirrel burrows. They are deep enough so that the posterior end
of the tortoise's shell is flush with the arroyo wall (Auffenberg, in press).
At the extreme northern end of the range, in the area described by Woodbury
and Hardy (1948), the tortoises have different ranges and shelters in
summer and winter. In the summer they move from the upper reaches of the
arroyos onto the flats where they excavate short burrows. In the winter
they hibernate in communal burrows excavated in the arroyo walls. The
seasonal changes of shelter are accompanied by seasonal changes of activ
ity ranges. The summer and winter activity ranges do not overlap.
Gopherus polyphemus usually lives on sandy soil where It constructs
a long, usually nonbranched burrow. New burrows may be constructed by
adult individuals, but normally each individual uses a single burrow
throughout its life. Thus individuals of £. polyphemus have a restricted
activity range (Auffenberg, in press).
Very little is known of G. flavomarqinatus except that it excavates
burrows in the playa soils of the Chihuahuan desert community in Mexico.
The presence or absence of an individual activity range has an
effect on courtship. Tortoises, such as G. polyphemus. which have indi
vidual activity ranges must leave their customary area in order to mate.
Nomadic tortoises, such as G.. berlandieri regularly make contact with
other tortoises. Therefore the portion of courtship involved in finding
the opposite sex might be expected to differ in each of the above circum
stances.

METHODS
Field and laboratory studies were performed to Investigate the
courtship and combat behavior of Gopherus berlandleri. The field work,
begun In November, 1963, and completed In October, 1967, represents a
total of 103 days.
It Is difficult to obtain detailed Information In the field to
clarify the sequential behavioral events of courtship and combat behav
ior. These tortoises are nomadic, small, shy, and reach maximum popula
tion densities In relatively thick, thorny brush. Many days were spent
In the field without seeing courtship or combat, yet this paper represents
the most intensive Investigation of tortoise courtship and combat behav
ior publI shed.
Laboratory experiments were designed to analyze behavior sequences,
specifically the nature and Importance of the cues used by £. berlandleri
to distinguish sex In Its own species. I rejected fully the Idea of
making the study entirely experimental. Observations of such complex
behavioral Interactions as courtship and combat made only on captive
animals do not necessarily accurately reflect similar behavior in nature
(Carpenter, 1962). My experiences have shown that tortoises kept together
soon become accustomed to one another with the result that the frequency
of courtship or combat behavior is reduced. Such tortoises evince re
newed courtship or combat behavior when strange Individuals are intro
duced.
8

9
All of the courtship and combat observed In the field suggested that
the front and rear portions of the tortoise were the most likely sources
of olfactory cues relating to sex and species Identification. The most
obvious possible source of odoriferous material at the anterior end of
the tortoise Is the chin glands described in a later section. The
cloaca was considered a probable source of olfactory cues at the posterior
end. Cloacal scent is known to be Important in sex discrimination in
Geochelone carbonaria and (5. dent iculata (Auffenberg, 1965). Movements
of the tortoise were potentially Important visual cues. The experiments
with G. berlandlerI were designed to Investigate the roles of odors from
the cloacal and chin glands and tortoise movement In courtship and combat
behavior. The following testing devices were used in the experiments.
The open square.-These tests were based on the hypothesis that
there Is no differential investigative response between male and female
tortoises to other male and female tortoises and to controls. The test
apparatus (Fig. 2) consisted of an open topped box. The floor was
covered by screen wire. In the center of the box was a felt square. A
small, removable cage with wire sides was placed on rubber mats within
the felt square on the floor of the large box. A Grayson-Statler vacuum-
switch-sensor (Model E4690L) was connected to one of the wire sides of
the small test cage and to a digital counter and a Grayson-Statler drlnk-
ometer panel counter (Models E4690A-I and #370QA, respectively). The
switch operated on a .06 millivolt differential which apparently was not
detectable by the tortoises and assured maximum sensitivity. A circuit
from electrical ground to the sensor was closed when the tortoise,
grounded by the screen on the floor and the water dampened felt, touched
the wire sides of the small cage. The digital counter recorded each
closure of the circuit.

10
experimental tortoise; C, vacuum tube sensor; D, wire leads from
sensor to digital counter. The pen, B, is five feet in length and
width and 18 inches high.

n
A
Figure 3
Closed square apparatus. A, removable cage; B, five gallon aquarium;
C, air tight plastic seal; D, hose providing air to tortoise acting
as stimulus.

12
Figure 4
Scent testing chamber. A, pen containing experimental tortoises;
B, jars containing odor stimulus; C, leads to sensor and digital
counters. The chamber Is six feet long at the front, four feet
wide, and one foot high.

13
Figure 5
External view of actively secreting chin glands, G, of a male Gopherus
berlandlerl.

14
The closed square.-Both live and preserved tortoises were used as
stimuli to test the hypotheses that male and female tortoises respond
equally to the sight and movement of other male and female tortoises.
The closed square apparatus included that of the open square, but with the
addition of an aquarium placed Inside of the small, removable cage
(Fig. 3). The top of the aquarium was sealed with a plastic bag fitted
around a wood frame attached to the top of the aquarium. Air was provided
to the animal by means of a long plastic hose.
The scent chamber."A metal bottomed cage (Fig. 4) was used as a
chamber In which reaction to scents was tested. Glass jars with wire
fronts were recessed Into the front wall of this chamber. One Grayson-
Statler sensor was connected to the wire front of each of the jars.
Samples of potentially important scent producing material was placed in
the jars. A circuit was closed when a tortoise's nose touched the wire
front of the jars.
Hormone injections.-Thyroxine, progesterone, and testosterone were
injected subcutaneously to certain individuals In an effort to stimulate
courtship or combat behavior. Injections of these hormones were made
to also evaluate their role in the functioning of certain glands charac
teristically appearing on the chins of the species of Gopherus (Fig. 5)
The glands, described later, are believed to influence courtship and com
bat behavior In Gopherus.
Photographs.-Photographs were made of tortoises engaged In various
aspects of courtship and combat behavior. Both 8-mm and 16-mm motion
picture film was used. Numerous 35~mm photographs were made, particularly
In the field. The motion pictures and still photographs were used to eval
uate the type and extent of each behavioral element occurring In courtship
and combat behavior.

BEHAVIORAL AND PHYSIOLOGICAL ELEMENTS
IN COURTSHIP AND COMBAT
As In other animals the reproductive activities of Gopherus
berlandleri are an Interaction of physiological and behavioral elements.
While the scope of this paper Is not to trace the major hormonal and
other chemical changes affecting courtship and combat behavior, one such
aspect In JG. berlandleri Is of such relevance that It Is Included here.
From the start of this Investigation In November, 1963, field obser
vations of (1. berlandleri suggested that breeding behavior In this spe
cies seemed to be correlated with the enlargement of a pair of large in-
tegumantary glands located ventrally and slightly medially on each man
dibular ramus (Fig. 5). Smith and Brown (1946) reported them as being
found only In G. berlandleri and Interpreted them as degenerate capsules
of connective tissue. However In his description of Gopherus berlandleri.
Agassiz (1857) compared the chin glands of this species with the similar
glands of G. polyphemus. Grant (1936) had already reported chin glands
in G,. agasslzl and lately Legler and Webb (1961) have described them In
G. flavomarglnatus. Among tortoises these glands are known only In spe
cies of Gopherus. Chin glands are well known In rabbits, where their
secretion Is used to mark territorial boundrles (Mykytowycz, 1965). In
Gopherus the glands are larger in males than in females, and larger In
G. agasslzl and (5. berlandleri than In G. polyphemus or G.
flavomarglnatus.
Auffenberg (1966a) found that female G. polyphemus rubbed their
15

16
forearms against the jaw In the region of the glands during courtship.
I have observed similar behavior by male G,. Polyphemus. There Is an en
larged scale on the forearm of all species of Gopherus which Is In the
proper position to be rubbed across the gland. This scale Is best de
veloped In G_. polyphemus and £. flavomarglnatus. An Investigation of
the histological properties of the gland (Fig. 6) and an electrophoretic
analysis of the chin gland secretion was begun In January, 1967 (Rose,
Weaver, and Drotman, ms). Histological examinations showed that they
are functional In both males and females and are similar In structure
to mammalian sebaceous glands. They open to the outside by two or three
ducts, and their secretory activity varies seasonally. In the Browns
ville, Texas, area the glands of adult males begin to enlarge In June,
and by July they are fully enlarged in both adult males and females. In
nature the glands of specimens from this population remain enlarged until
at least December. Most specimens maintained In an Indoor pen on a fif
teen hour day had the glands enlarged until early January. By the end
of January the glands of most of the tortoises had receded. These tor
toises were moved to a large outdoor pen In the Gainesville, Florida,
area on February 1, 1967- The glands of all tortoises had fully receded
a week later and no secretory material could be obtained by gently
squeezing the gland as was possible In previous months.
Electrophoretic analyses of the glandular secretions In species
of Gopherus show that the secretion contains proteins, an esterase, and
three classes of lipids. The lipid classes are triglycerides, fatty
acids, and a steroid, cholesterol, interspecific variation exists in the
number of esterase bands and in the proteins present in the secretion.

Figure 6
Histological section of the chin gland of a male Gopherus berlandleri.
This section, made In November, 1966, shows collecting duct lined
with epithelial cells. The mass In the duct Is composed of cells that
have built up their products and have been discharged into the lumen
as Is typical of holocrine glands. The base of thegland Is at the
bottom of the photograph.

18

19
B F A
CZ3
CI3 CZ-5 O
CZ3
D +
Figure 7
Diagrammatic representation of the protein bands in the chin gland
secretion of Gopherus species. B, Gopherus berlandieri; F,
f lavomarginatus ; A, G_. agass i z i The females but none of the males
of the living species of Gopherus have a negative protein band.

20
Table 1
Behavioral Elements in Tortoise Courtship and Combat
Head bobbing Geochelone travaneorica (Auffenberg, 1964)
GL carbonaria (Auffenberg, 1965; Snedlgar and Rokosky,
1950)
G. denticulate (Auffenberg, 1965)
Gopherus agasslzl (Nichols, 1957; Woodbury and Hardy,
1948)
_G. berlandlerl (Householder, 1950)
£. f1avomarglnatus (Legler and Webb, 1961)
_G. polyphemus (Auffenberg, 1966)
Trailing Geochelone carbonaria (Snedlgar and Rokosky, 1950)
elephantopus (Watson, 1963)
G. pardalis (Watson, 1962)
Gopherus agasslzl (Nichols, 1957)
Gi. berlandlerl (Hamilton, 1944)
J. f 1 avomarglnatus (Legler and Webb, 1961)
G,. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglis, 1963)
Courtship position
Homopus areolatus (Eglls, 1962)
Smelling Geochelone carbonaria (Auffenberg, 1965)
G.. dentIculata (Auffenberg, 1965)
Gopherus agasslzl (Camp, C. L., 1916)

21
Biting
Ramming
Table 1 continued
G. berlandlerl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Cherslne angulata (Rose, 1950)
Geochelone dentIculata (Beltz, 195*0
G. elephantopus (Heller, 1903)
Gopherus agassizl (Woodbury and Hardy, 1948; Camp, 1916;
Grant, 19^*6)
G,. berlandlerl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Testudo graeca (Domerque, 1899; Nikolskii, 1915;
Watson, 1962)
Cherslne angulata (Rose, 1950)
Geochelone carbonaria (Auffenberg, 1965)
G. dentfculata (Auffenberg, 1965; Beltz, 1954)
G_. elephantopus (DItmars, 1910; DeSola, 1930)
G.. ocul 1 fera (Fitzsimmons, 1935)
G,. travancorlca (Auffenberg, 1964)
Gopherus agassizl (Nichols, 1953; Miller, 1932)
.G. flavomarqlnatus (Legler and Webb, 1961)
G,. polyphemus (Carr, 1952)
Testudo graeca (Watson, 1962; Nikolskii, 1915)

Table 1 continued
Circular movement of courting pair
Gopherus agasslzl (Woodbury and Hardy, 1948)
polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Vocalization Geochelone carbonaria (Snedigar and Rokosky, 1950)
_G. dentIculata (Grant and DeSola, 193*0
G_. elephantopus (Watson, 1962; Heller, 1903; DeSola
1930)
£. oculifera (Fitzsimmons, 1935)
G,. pardal is (Watson, 1962)
Gopherus berlandieri (Householder, 1950)
Testudo graeca (Watson, 1962; Nikolskii, 1915)
Presentation Geochelone elephantopus (DeSola, 1930)
Gopherus agasslzl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)

23
A
B
C
SECONDS
0 1
Figure 8
Action patterns of head bobbing. A, Gopherus berlandieri; B,
£. agass i z i ; C, G_. polyphemus .

24
The protein concentration In females of all species of Gopherus Is much
lower than In males. Females of all species of Gopherus had a cathodal
migrating band which was absent in males (Fig. 7).
The courtship and combat of tortoises Is a complex series of behav
ioral Interactions. The particular sequence of these elements vary
Interspecifleally, and In some species some elements are absent. Cer
tain behavioral elements have been recorded frequently enough In differ
ent and unrelated species to imply the existence of a generalized type
of tortoise courtship or combat consisting of common behavioral elements.
Table 1 lists nine behavioral elements of courtship or combat behavior
which are found in species of Gopherus. At present more courtship and
combat behavior Is known for species of Gopherus than for any other
tortoise species Thus Gopherus Is here used as a comparative base in
considering behavior in other tortoise species. Listed in Table 1 are
also other tortoise species for which each of the behavioral units found
in Gopherus berlandleri have been observed.
Head bobbing -This movement is known for most tortoises and is per
formed in a characteristic fashion in different taxa (Eglis, 1962). It
is also one of the most frequently observed movements of tortoises
during courtship and combat. Eglis (1962) recognized that head movements
in tortoises are latolent (lateral) or dirolent (straight). Eglis stated
that the head movement of living species of Gopherus is basically
dirolent. In Gopherus the neck is usually fully extended and the head
is nodded vertically. The action pattern diagrams (Fig. 8) compares the
duration, magnitude, and frequency of the vertical bobbing in three
Gopherus species.

25
Individuals of all species of Gopherus bob their head when objects,
such as food, are being smelled. It also occurs In meetings between two
or more tortoises, and In Gopherus reaches its greatest frequency during
courtship and combat. Bobbing is performed by both sexes, but in court
ship the male bobs more actively than the female. Low intensity bobbing
is performed when the head is not fully extended. Bobbing movements are
often observed when the head is nearly completely retracted, but are
associated with breathing and not olfaction. Head bobbing sequences are
variable in length and have no discernible pattern correlated with either
sex or species in Gopherus. except that the sequences are usually longer
during social Interactions than when food or feces are being smelled.
The bobs performed in courtship and combat are apparently identical.
The only clearly demonstrated function of head bobbing in tortoises is
that of a species recognition in Geochelone carbonaria and (5. denticulata
in which the head movement is lateral (latolent) and has been demonstra
ted to act as a species specific visual signal (Auffenberg, 1965).
Trailing.-This behavioral unit (Stage 1, Table 2) marks the start
of courtship, and to a lesser extent combat. A male trails either a
female in courtship or a male In combat. In Gopherus berlandieri court
ship the male walks behind the female with his head extended, bobbing at
irregular intervals. This behavior occurs at the beginning of courtship
or combat, and may last for nearly an hour. Male G.. berlandieri make no
attempt to overtake the female during this early stage. If she stops,
he stops; the rate of the female's activity influences that of the male.
The male's attention is directed toward the female during this stage,
and his behavior is dependent on hers. She often grazes during this
period. In the courtship of G.. polyphemus the female often walks

26
actively toward the male. Obviously trailing will eventually bring the
male and female together physically, but the significance of Its rltual-
llke cadence In the early part of courtship In 6. berlandler! Is unknown.
Eglls (1963) reported an Instance of a male Homopus areolatus
following a female In a peculiar manner: The male's front feet were limp
and the entire locomotion was accomplished by pushing motions of the rear
feet.
Courtship position.-A distinct courtship stance has been reported
only for Homopus areolatus. However In confrontations between captive
male Gopherus polyphemus a stance or positioning of bodies occurs con
sistently enough to be considered In this behavioral category. In
Homopus the male faces the female with their shells at a 90 angle
(Eglls, 1963). This positioning Is accomplished by the male's rushing
around first one side and then the other of the female. In meetings
between male Gopherus polyphemus a similar position may also be achieved.
The position Is achieved by the more aggressive specimen, but seems more
dependent on the timidity of the nonaggressIve male than on strenuous
efforts by the aggressive male as In Homopus areolatus. No similar
positioning has been reported for other species of Gopherus: nor have I
observed any.
01 fact Ion.-Ma1e tortoises appear to smell various areas of females
or other males In all the courtship and combat encounters observed, and
In those reported In detail In the literature. The movement associated
with olfaction In Gopherus Is the head bob. However the head bobbing
observed In most courtship or combat situations differs in minor but
consistent ways from those observed when food or feces are being examined.
These later head movements In Gopherus have a predominant forward motion.

27
Olfaction In Gopherus is a simple dirolent motion with little of the
vertical component which essentially characterizes head bobbing as seen
in courtship or combat. Thus a distinction exists between the types of
head movements performed when odor is the only stimulus, as opposed to
the head movements seen in the head bobbing of courtship or combat when
factors other than, or in addition to, olfaction are Involved. During
meetings between tortoises head bobbing of the kind observed when food
or feces are examined occur repeatedly. In these true olfactory move
ments, as opposed to head bobbing, the head is directed toward the front
and rear portions of the other tortoise's shell.
Biting.-in Gopherus berlandleri biting occurs in both courtship and
combat. I have never observed biting in the combat of G,. Polyphemus.
It is reported in the combat of £. agassizi (Camp, 1916; Woodbury and
Hardy, 19*+8; Grant, 19*+6). During courtship males of £. berlandierl bite
the females on the head, front legs, and the front edge of the carapace.
As courtship proceeds biting becomes increasingly confined to the ante
rior edge of the female's carapace. Biting also occurs in combat in this
species. Both males may bite one another very forcibly, although I have
never seen Injuries. During the courtship of G,. polyphemus the males
bite the head and front feet of the females, but confine most of the
shell biting to the female's guiar projection and the anterior carapace
edge is not biten. Camp (1916) and Woodbury and Hardy (l9*+8) report
biting In both courtship and combat of G,. agass izi. Eglis (1963) reports
that a courting male Homopus areolatus vigorously bit the head of a fe
male. I have seen female Geochelone elephantopus produce serious
wounds by biting exposed areas of Gopherus po1yphemus, although the
biting was not In a courtship or combat context. Beltz (195*+) reports

28
that a male Geochelone dent 1 culata attacked a large Gopherus agasslzl by
biting and ramming its shell and limbs. Biting in tortoise courtship Is
not universal and in at least one species, Geoche1 one t ravancorIca. court
ship occurs without any biting (Auffenberg, 1964).
Ramming.-Ramming of the female by the male during courtship Is
known for all tortoise species whose courtship is well reported. In the
courtship of Gopherus beriandierl the male rams the female's sides more
frequently than other parts of her shell. In combat ramming tends to be
confined to the front ends of the shell of the opposing males. Ramming
In combat often develops into a pushing contest Instead of an exchange
of blows. In either case one male attempts to place his guiar projection
under the plastron of the other and overturn him. This effort results
In a distinctive upward thrust at the end of each ramming movement. This
upward arc is missing from courtship ramming In £. beriandierl. The
ramming motion begtns from a position in which the tortoise is standing
on all four legs. The movement Is Initiated by a slight backward rocking
movement on all four legs, Immediately followed by a sudden forward
thrust in which the head and, to a lesser extent, the front legs are
withdrawn. The withdrawal of the front legs gives a decided downward
angle to the forward thrust. In combat ramming the front legs are ex
tended fully on Impact, thus providing the characteristic upward arc.
In courtship ramming the front legs do not appear to be withdrawn;
there is no upward arc at the end of the forward thrust; the ramming
movement is on a more horizontal plane. In Gopherus. and other species,
ramming has the function of Immobilizing the female In courtship and
the male in combat.

29
Watson (1962) reported that the ramming of female Testudo graeca
Ibera by the male had a distinct rhythmic quality that I have not ob
served In any species of Gopherus. Dltmars (1910) reported a peculiar
lateral bumping In the courtship of Geochelone elephantopus. This report
did not clearly describe how the lateral bumping was accomplished.
Locomotion.-During certain phases of courtship in Gopherus
beriandierl. G. poiyphemus. and G_. agassizl the female appears to avoid
a face to face confrontation with the male by retreating. Her path of
retreat Is usually circular or semicircular, since the male charges,
bites, and rams the female first from one side and then the other, always
attempting to meet her head on. The result In JG. berlandleri Is a circu
lar movement of the courting pair with the male moving In an outer,
larger circle and the female In an Inner, smaller circle. In combat
between some male £. berlandieri a similar circular retreat pattern
arises when one male, the less aggressive of the two, attempts to avoid
the more aggressive male and thus occupies the Inner circle. In the
courtship of G.. polyphemus the female avoids the male by a similar re
treat pattern.
In Homopus the male circles the female to ram or bite her, but she
does not avoid him by turning away In the circular path described for
Gopherus. but would "agitatedly skitter aside" (Eglls, 1962).
VocalIzatIon.-VocalIzatlon has been reported for several tortoise
species during courtship or copulation, but not during combat.
Van Denburgh's (191*0 account of vocalization In the combat of Geochelone
elephantopus has been questioned (Auffenberg, 1965). In Gopherus It has
been described for G,. berlandieri by Householder (1950). Householder's
description was based on a courtship between two tortoises he presumed

30
were desert tortoises, Gopherus agasslzl. Woodbury (1952) later showed
that the male of this pair was actually a Texas tortoise £ berlandlerl.
Campbell and Evans (1967) reported vocalization In Gopherus agasslzl.
but the vocalization was not In a courtship or combat context. Most
reports of vocalization durtng breeding activities suggest that such
sounds are a by-product of the effort expended In copulation. There Is
no Indication that vocalization serves as an auditory signal. However,
the males of Geochelone elephantopus bellow before copulation during the
breeding season (Van Oenburgh, 191*0, and males of £. carbonaria vocalize
prior to copulation (Snedlgar and Rokosky, 1950). This latter observation
was made on what W8S presumed to be Geochelone denticulate. However, the
photo In Snedlgar and Rokosky's paper clearly shows that the tortoises
were G. carbonarla.
Presentation.-A female facilitates successful Intromission and In
higher vertebrates Invites copulation by presentation. In Gopherus
berlandlerl the female holds her body In a characteristic position and
extrudes her cloaca. The female's stance Is one with head and forelimbs
withdrawn and rear limbs partially extended. In Gopherus polyphemus the
presentation Is similar but the female's rear legs seem to be extended
more stiffly than In £. berlandlerl end she may pivot so that the rear
of her shell Is nearest the males head. I have never observed this In
G. berlandlerl.

31
Table 2
Stages of Courtship observed In
Gopherus berlandlerl
Stage
Male
Fema1e
1.
Follows female and occasionally
bobs head
Indifferent to male
Increased vigor of head bobbing,
rate of walking surpasses that
of female
Increases walking speed
2.
Overtakes female, bites her
feet, carapace
Trles to avoid male,
turns away from him,
both describe a circular
pattern
Rams female
Withdraws head and front
feet, rear feet remain
extended
3.
Initial mounting attempts
Remain still, or may
attempt to walk away
Rams and bites If female
tries to walk away
4.
Coition

Figure 9
Stages of courtship In Gopherus berlandierl. A, trailing; B, ramming; C, biting, D, mounting

33

COURTSHIP IN GOPHERUS BERLANDIERI
The field observations for courtship were made In Texas In Cameron
County, near Brownsville, and In Webb County, near Laredo. My earliest
observations of courtship were in June, and the latest In November.
Some courtship was observed In outdoor enclosures at the Welder Wildlife
Refuge near Sinton, San Partido County, Texas, and Gainesville, Alachua
County, Florida. Twelve complete courtship sequences were observed In
the field and approximately twelve Incomplete performances (less than
three of the four stages In Table 2) were observed In the field and
among captive specimens.
Behavior preceding copulation can be treated in four stages (Table
2). Stage one Is a relatively passive phase during which the female
shows little active response to the male's presence, but during which she
modulates the male's behavior. In the remaining stages the female's
behavior Is modulated by that of the male.
Stage one.-Courtship behavior begins with the male trailing a female
(Fig. 9"A). Initially the male walks behind the female and his behavior
Is modulated by hers. This Is shown by two major characteristics of the
trailing phase; (1) whenever the female stops the male stops and, (2) the
male often bobs his head In the female's direction. During the early
portion of the trailing stage the male walks with his neck usually only
partly extended. The female does not bob her head at any time during the
trailing stage. During this initial stage of courtship the female's
34

Figure 10
Sexual dimorphism in Gooherus berlandlerl. Hales (left) have a deep
posterior pi astral depression, thickened anal notch margins, and an
elongate guiar projection at the anterior end. The female's plastron
(right) is flat without thickened anal notch margins and has a shorter
guiar projection. The posterior ends of both tortoises are at the
bottom of the picture.

36
behavioral role Is largely one of Indifference. She normally grazes and
"noses" at various items on the ground, displaying the same movements
and activity as that observed for lone, unattended females. In some
trailing the female makes one or more stops in the shade. During these
stops the male appears to lose Interest, and may even graze. When the
female resumes walking, the male assumes his previous behavior. These
shade stops may be a temperature regulating behavior.
Late in the trailing stage, which may last from a few minutes to
nearly an hour, the male shortens the distance between himself and the
female. When he Is about three feet directly behind the female he
increases the frequency and vigor of head bobbing and when not bobbing
holds his head in a high, arched position. His neck Is Inclined between
25 and 35 but the top of his head Is parallel to the ground. At this
point the female increases her walking speed, and ceases all grazing
activity. This shift In the female's behavior marks the end of stage
one.
Stage two.-The second stage of courtship marks the start of phase
two, Is more intense than the first stage, and begins when the male
attempts to overtake the female and confront her face to face. The
male overtakes the female and stops her by biting her head, front feet,
the top, front edge of her carapace, and ramming her forcibly with his
massive, elongate guiar projection (Fig. 9B, C; Fig. 10). The female
first avoids the male; he consistently tries to establish a face to face
position with her. The female turns away from the male, which results
In both tortoises moving In a circular path of constantly diminishing
diameter. The male continues to Increase the Intensity of biting and
ramming; finally the female withdraws her head and front legs but

37
continues to pivot her anterior end away from that of the male by driving
with her rear feet. The male's biting tempo Increases, but his head
bobbing stops or loses any recognizable pattern. Biting of the female
by the male is Increasingly confined to the nuchal and anterior peripheral
bones. The bites become very forceful, the male often grasping a portion
of the female's shell in his mouth and alternately pushing and pulling
her. The female now withdraws her head and front feet, leaving her rear
feet extended. Her position is therefore an incline, with the rear of
her shell highest. She no longer pivots and the male attempts to mount
her. The stimulus or releaser for mounting behavior in the male seems
to be the female's Inclined position. Observations by Walter Auffenberg
made near Laredo, Texas, suggest that the female selects the place where
stage two and the subsequent stages occur. This is usually an area re
latively free of underbrush.
Stage three.-Initial mounting attempts by the male may occur any
place on the female's shell. If the Initial mounting occurs at other
than the rear of the female's shell, the male works his way to the rear
with his front feet on the dorsal surface of the female's carapace,
and his rear feet on the ground (Fig. 9-D).
Stage four.-None of the unions I observed lasted over ten minutes.
They were usually terminated when the female walked out from under the
male. Householder (1950) reported that a female of G,. berlandieri (he
thought it was a female £. agasslzi) everted part of her cloaca which
seemed to facilitate Intromission by the male. This occurs in female
Gopherus polyphemus and Eglis reported similar behavior in Homopus. I
did not, however, observe this in £. berlandieri courtships. Each thrust
by the male during copulation pushes the female forward. To compensate

38
for the female's change of position the male performs a series of hop-
steps with his rear feet, if intromission occurs in a brushy area his
rear legs become tangled in the grass, the hop-step is impeded, and copu
lation is interrupted. Thus the female's selection of an area relatively
free of underbrush helps ensure successful coition.
From 7:00 until 8:00 p.m. I watched a pair trailing (Stage 1, Table
2) on the northeast side of one of the lomas (dunes) characteristic of
the Jackass Prairie, near Brownsville, Texas. The male was bobbing his
head in a series between 3 and 36 bobs. The male stopped when the fe
male stopped. At two different times during this sequence the individ
uals were facing one another at approximately 110; the male's head was
In the female's field of vision, but she did not reciprocate with head
bobs. Just before dark (7:30 p.m.) the female stopped in an open area
with scattered clumps of grass (Bouteloua) and prickly pear (Opuntla):
she headed Into a clump of grass and came to a halt. The male stopped
both walking and head bobbing. The female withdrew head and feet. The
male's head protruded about l£ inches. Both had remained in these
positions when l left the area at 8:00 p.m.
I returned at 5:15 a.m. The tortoises were in the same place and
In the same positions as when I left them. At 7:10 a.m. the male fully
extended his neck at an angle of about 20 and immediately resumed
bobbing in sequences averaging seven bobs. However, his head was not
In the high arc I have observed in other courtships. By 7:27 a.m.
neither tortoise had moved from the spots they had stopped earlier the
previous night. Now the male began to hold his head in the high, arched
position. At 7:35 a.m. the female started to walk and was followed
immediately by the male bobbing his head. By 7:40 a.m. the male skirted

39
the female on her right. She turned away from him counter-clockwise and
he followed, still bobbing. He bit the anterior end of her shell and she
withdrew her head and forefeet. By 7:^5 a m. the female was no longer
turning away from the male The male's bites were more forceful, he
grasped, pushed and pulled the female. At 7:50 a.m. he mounted her,
holding his mouth open during copulation I heard no sounds from him,
but both the wind direction and my distance of 30 yards from the pair may
have dampened any vocalization At 7:58 a.m. the female walked out from
under the male He followed her for five or six feet and made a few
slow, low intensity head bobs. The female moved into a pallet, the male
walked away.

40
TABLE 3
Stages In the Courtship of Gopherus polyphemus
(after Auffenberg, 1966)
Stage
Male
Female
1.
Walks In circle and bobs head
Approaches male
2.
Bobs head violently with
approach of female
3.
Bites female on legs and shell
especially guiar projection
4.
First mounting attempts (usually
unsuccessful) followed by more
Moves backward in semi
circle; stretches hind
legs
biting
Radius of semicircle
becomes so small that
female begins to pivot
180 about a central
point
5.
First successful mountings and
finally coition

COURTSHIP IN OTHER GOPHERUS SPECIES
The courtship of Gopherus Polyphemus has been described by Auffenberg
(1966) and differs In several respects from that of G. berlandlerl. In
no Instance have I seen female G.. berlandleri make an Initial approach
to male G,. berlandlerl as occurs In £. polyphemus (Stage 2, Table 3).
Head bobbing Is faster In polyphemus than In berlandleri (Fig. 8).
Ramming of the female by the male Is similar In both species, but the
biting (Stage 3, Table 3) differs In that G,. berlandlerl males have not
been observed to bite the guiar projection of G. berlandleri females.
The courtship is similar In the two species In that during the biting
phase of courtship females of both (5. polyphemus and G_. beriandieri move
backward away from the male in a circular path. (Stage 2, Table 2;
Stage 4, Table 3)
The only reference to courtship or combat behavior in G,.
flavomarginatus is by Legler and Webb (1961). They observed that males
initially assume an aggressive role and that the females did not approach
the male as in the early part of courtship in G. polyphemus. Male and
female (5. flavomarginatus have a tendency to push or crowd tortoises
against an object such as a fence post or rock. In one instance a fe
male £. flavomarginatus crushed a female and on another occasion a male
G. polyphemus against a fence post so forcibly that the shell of the G.
polyphemus was fractured In several places (Francis L. Rose, personal
communication).
41

42
Courtship observations on J3. aqassizl are numerous but are lacking
in detail. Householder (1950) provided a good account of what was
assumed to be successful courtship in JG. agasslzi. However, the tortoise
pair involved were later Identified by Woodbury (1952) as a male G.
berlandieri and a female G_. agasslzi. Woodbury and Hardy (1948) de
scribed a courtship (?) of G,. aqassizl but omitted the kind of detail
useful in comparing this behavior to that in other species. This is true
of most of the published accounts of courtship In tortoises Our knowl
edge now demands that meticulous observations be recorded of all of the
behavior involved In courtship or combat Tortoise behavior varies in
significant but often extremely subtle ways as does tortoise morphology.

COMBAT IN GOPHERUS BERLAND1SRI
Combat between males begins before the breeding season and drops
off sharply In frequency before the breeding season Is over. The
following observations are based on three complete and four partial com
bat sequences seen in the field and on many partial sequences observed
among captive tortoises. I have seen combat between captive males kept
In an outdoor pen as early as March and combat has been observed in the
field as late as July.
True combat In Gopherus berlandlerl occurs only between males. I
have seen only one instance of antagonistic behavior between adult
females which Involved only pushing.
Two aggressive males approach each other and ram. One combatant
attempts to overturn the other. One male walks toward another or both
move toward each other. Their heads may be motionless or bobbing
vigorously. At first ramming is mutual. This type of combat In which
both tortoises are Initially aggressive will be called Type One combat.
Another kind of combat, Type Two, occurs between males if one Is clearly
dominant and the other is not aggressive. The dominant tortoise rams
and bites the subordinate one in a series of movements similar to those
In Stage Two of courtship. The dominant male rams and even bites the
subordinate male on the front feet, head, and the same part of the shell
he does on the female during courtship. The subordinate male avoids the
aggressive male by pivoting from the aggressor In the same circular
43

44
turning pattern of the female described In courtship. The dominant male
was never observed to attempt to mount a subordinate male. Thts type of
combat ends when the subordinate male escapes to a pallet or withdraws
all appendages and remains still. Biting Is not a major component of
Type One combat, in contrast to Type Two combat.
Type One combat occurs when neither male becomes subordinate. Both
males engage In ramming and biting, and both attempt to overturn the
other with their guiar projections. Dominance is apparently established
when one overturns the other, or when one flees the combat area after a
ramming and pushing contest. Evidence of the combat often remains on
the ground In the form of a large circular area in which the soil has
been tramped by the feet and piastra of the combatants. Similar areas
are left after stage two of courtship (Table 2). At the end of Type Two
combat the victorious male holds his head at a higher level than that of
the defeated male. If combat terminates by one tortoise fleeing, the
loser will retreat with its head extended directly in front, and the
winner pursues with its head inclined about 30.
The following account of Type Two combat is taken from my field
notes taken at Slnton, Texas, 3 August, 1965.
Lake Camp at 10:00 a.m.: I observed fighting between two males of
the 34 tortoises kept in the yard. A large male (male one) walked
rapidly from a clear place on the lawn to a fence 10 feet away where
there were three females and a small male (male two). Male one immedi
ately rammed the smaller male and blocked his access to the females.
The male tortoises bobbed their heads when facing one another. The
smaller male two was passive at first and was turned completely twice
around by the rival. After twice being turned around the smaller male

*5
bobbed and lunged at the larger one. After a short pause during which
both were Inactive male two walked toward the center of the lawn away
from male one. Male one followed Immediately and bobbed his head In the
direction of male two. The following of male two by male one was exactly
like trailing In courtship (Fig. 9"A). Male two played" the female
role as he nosed Items on the ground and slowed his walk. The chase"
covered about 30 yards and lasted until 10:20 a.m. Then male one over
took and gently bit the anterior end of male two's carapace. Male
two promptly withdrew all appendages. At 10:23 a.m. the chase began anew,
male one tried to overtake male two and bite his head. At 10:25 a.m.
male two found and entered a grassy depression and remained there.
Male one stood behind male two and bobbed his head. Movements by male
two caused male one to ram the exposed rear of male two's shell. At
10:30 a.m. male one still stood behind male two who remained In the
depression. Male one continued to bob his head In the direction of
male two at Irregular intervals. After a short while male one walked
away.
Mr. Kenneth G. Mentocha and Robert L. Snavely, then students at the
Rob and Bessie Welder Wildlife Foundation of Sinton, San Patricio County,
Texas gave an excellent report of type one combat. The combat occurred
Just southwest of Sinton, Texas.
24 July, 1965 6:40 p.m.2 gopher tortoises In combat." Heard
noise in brush about 20' away. Sounded somewhat like a javelina moving
through the brush. Both tortoises were between a Xanthoxylem and a
Ce 111s pallida, pushing each other with the guiar projections. After
about 1 minute they backed off and began to breath heavily as if they
had been at the "fight" a long while and were catching their breath.
After about 30 seconds they again begin the combat. While in close
contact, the smaller tortoise continually bit the front portion of the
carapace of "Stubby."* "Stubby" seemed to be the stronger of the two
*"StubbyThe larger of the 2 tortoises. Had no claws on left
front foot, but a large callous.

46
and pushed the smaller one around quite a bit. He (Stubby) Mould put
his guiar projection beneath the plastron (mostly In the front) and
begin to lift the other In an apparent attempt to turn It over. Three
or four times, when the smaller tortoise appeared as If It would be
turned over, It would place Its forelImbs over and around the back of
those of "Stubby" and appear to be holding on In order not to be turned
over. Stubby pushed the other tortoise backward several times but most
often Into a bush and could not turn It over due to the resistance of
the bush.
About 7:10 p.m. the two finally came Into an open area during the
combat ("Stubby" pushed the other tortoise Into the open), and during a
time of "combat" when both had their head withdrawn and were pushing on
one another, I flipped the smaller tortoise onto Its back. "Stubby"
then came up to the other tortoise, which was trying to turn back over
and began to bite In on the side (edge) of the shell and left hind foot.
The smaller tortoise turned back over onto its feet and "Stubby" immedi
ately placed Its guiar projection under the side of the shell of the
smaller tortoise and turned it onto Its back again. This time the
smaller tortoise lay motionless and "Stubby" Just looked at it. After
about 30 seconds "Stubby" turned around and walked off. Both were
picked up in order to determine sex. This was about 7:15 a.m. A
circle (on the ground) of about 6' In diameter showed evidence of much
scratching which must have occurred prior to the above observations.
In a large outdoor pen in Gainesville, Florida, combat has been ob
served as early as March 12. In Brownsville, Cameron County, Texas,
local residents also reported tortoise combats as early as March.

COMBAT IN OTHER GOPHERUS
Less is known of combat In other species of Gopherus than of court
ship. Woodbury and Hardy (1948), and Grant (1936) reported that males
of G. aqasslzi charge one another with heads retracted. The contest
consists of attempts by one tortoise to overturn the other using the
guiar projection (Fig. 10) as both a ram and a lever. Miller (1932)
reported that hatchling JS. aqassizl would ram and lunge at each other,
or at an extended human finger.
Legler and Webb (1961) describe fighting In (5. fiavomarqlnatus: I
have observed no combat between captives of this species.
Carr (1952) reports on fights between males and females of Gopherus
polyphemus. I have seen ramming between a captive male and a female of
this species, and observed one particularly ambitious, moderate-sized,
malformed, male (5. polyphemus repeatedly ram subadult Geochelone
eiephantopus and an adult _G. pardal Is. both of which were at least 20
pounds heavier than the (. polyphemus. Some information on combat In
G,. polyphemus was gained by observing confrontations between male
Gopherus polyphemus In the laboratory.
In these experiments each of six adult male tortoises was marked
and kept in rectangular indoor pens. The room housing the pens was
automatically kept on a nine and one-half hour day throughout the
experimental period (February 1, 1965Aprtl 1, 1965). Air temperature
for the entire test period varied from 76 F. to 78 F.
47

48
For each trial two tortoises were placed diagonally from each other
in one of the rectangular pens. Prior to each trial I wet the tortoises
with water, a procedure which seemed to stimulate the tortoises. In
field situations I have observed that tortoises were more active after a
rain. A blind so placed as to hide me from the tortoises produced no ob
servable change In the tortoise's behavior and its use was discontinued.
The distances between tortoises when head bobbing first occurred was re
corded. Each trial lasted until the tortoises failed to react to each
other. Portions of the trials were recorded on 180 feet of motion pic
ture film. The analysis of these interactions including the filmed
portions follows.
The responses between two male (S. polyphemus consist of initial
responses, locomotion, head bobbing, mutual smelling, and establishment
of a dominant-subordinate relationship. I considered a tortoise highly
motivated if It reacted to the presence of another tortoise Immediately
upon start of the trial and poorly motivated if it delayed longer than
two or three minutes before reacting to the other tortoise. Contact was
defined as the moment two tortoises came together closely enough to
touch as a result of directed locomotion by one or both of the reptiles.
Initial responses.-Poorly motivated individuals spent three to four
minutes smelling the substrate of the pen or old feces before actually
pointing their head in the direction of the other tortoise. Highly moti
vated tortoises immediately began to walk in the direction of the other
tortoise. Tortoises with an Intruder placed in their pens either remained
still, immediately proceeded toward the Intruder, or In a few cases
turned into a corner.
Locomotion.-I defined locomotion as directed, that influenced by
another tortoise, and nondlrected, that apparently not influenced by

49
another tortoise. In directed locomotion of a highly motivated tortoise
the neck Is fully extended and walking Is rapid. Nondtrected locomotion
Is slower and the neck Is only partially extended.
Head bobbing.-EglIs (1962) classified head bobbing In Gopherus
as dirolent. This Is the typical head movement performed when smelling
substrate or food. In meetings between two tortoises bobbing usually
occurs first when the tortoises are about two and one-half feet apart.
The function of head bobbing In G_. poiyphemus Is not clear. The
fact that a tortoise is always directed toward another tortoise when
bobbing occurs suggests that a visual cue may be involved. However a
highly motivated tortoise continues to walk toward another tortoise
whether or not reciprocal bobbing or directed locomotion occurs. A
poorly motivated tortoise may not continue bobbing or walking in the
direction of another tortoise if no reciprocal head bobbing or
directed locomotion occurs.
In as much as the behavioral functions of head bobbing are largely
unknown, adjectives such as "contentment," "enthusiastic," "nod of
friendship" used In conjunction with head bobbing can serve only to
make ambiguous otherwise informative reports (Nichols, 1953).
Mutual smelling.-At contact the vertical bobs of both tortoises
assume a large lateral component and finally lose any recognizable
movement pattern. The head and feet of both tortoises are the objects
of smelling. The vertical bobs associated with these smelling move
ments are often Interrupted by a lateral wiping motion directed to the
surface of one of the forelegs. After one to two minutes of mutual
smelling, one of the tortoises becomes more active in all Its movements
than the other.

50
Pominance-subordlnance.-Pom 1 nance relationships are clearly demon
strated by the relative postures of the tortoises. The dominant tor
toise supports Its weight on all four of Its extended legs. He may
walk around the other tortoise, stopping often to smell his rear legs.
The submissive tortoise holds his head lower to the ground, with his neck
partially extended. If the dominant tortoise continues investigative
activity, the submissive tortoise positions himself at an angle of
approximately 45 to the dominant tortoise and he maneuvers so that one
side (either side) is always presented to the front of the dominant
individual. Such maneuvering is done with the rear legs and, pivoting
on the anterior portion of the plastron, the front legs continue to be
withdrawn. After one to two minutes of this behavior the more active
dominant individual will turn away, apparently no longer Interested In
the other tortoise. Pominance can be demonstrated by placing a small
amount of food In the pen with the two tortoises; the dominant tortoise
inhibits feeding by a subordinate tortoise.
The males of several tortoise and turtle species engage in shell
ramming during combat and for immobilizing the female prior to copula
tion (Auffenberg, 1964; Brumwel, 1940; Taylor, 1933; Nikolskii, 1915;
Hamilton, 1944). Carr (1952) reported ramming between males of G.
polyphemus; however, 1 observed none In these tests. However, observa
tions made in the spring and summer included ramming between males of
_G. polyphemus. and males of 6. polyphemus ramming males of Geochelone
elephantopus and (5. pardal is. Ramming in Gopherus berlandieri has been
discussed earlier in this paper.
The presence of a distinct dominant-submissive relationship in
Gopherus suggests that such behavior is species-specific. It is

51
conceivable that In meetings between males of Gopherus polyphemus (or
females In the nonbreeding season), noncombatlve recognition of dominance
would result In the subordinate tortoise leaving the area of the dominant
Individual. However, these particular experiments failed to show that
a given polyphemus is dominant to any Intruder Introduced into its
"home" pen. Instead there was a marked tendency for certain Individuals
to be dominant both In their own pens and In those of other tortoises.
Gene Gourly at the University of Florida Is currently completing a study
of orientation and territoriality in G,. polyphemus.

BEHAVIORAL ELEMENTS COMMON TO
COURTSHIP AND COMBAT
In both courtship and combat one member of the pair assumes an
aggressive role. In courtship it Is usually the male. Courtship ends
only when the female Is immobilized for intromission. Aggressive behav
ior In Type One combat of Gopherus berlandieri continues until one tor
toise is overturned or pushed away. And in Type Two combat until the
nonaggressive member of the pair escapes by fleeing or retreating to a
shelter. In some Instances a dominance relationship may be established
without fighting, as shown by the experiments using male Gopherus
Polyphemus. In (3. berlandieri dominance is established by behavior
common to both courtship and combat, particularly Type Two combat. This
behavior Includes head position, shell ramming, and biting.
When two male G_. berlandieri approach one another, or when a male
approaches a nonaggressive male, their respective head positions indicate
if the confrontation will be Type One or Type Two combat. An aggressive
tortoise holds his head higher and extends it further outward than a
nonaggressive tortoise. The subsequent behavior of the nonaggressive
male or female Is often seemingly unrelated to either combat or courtship.
In meetings between two aggressive tortoises both hold their heads
high, and each reacts aggressively. During the ramming and biting In
stage two of courtship the male tortoise's head is held higher than that
of the female, who finally retracts her head partially or fully just
prior to and during presentation.
52

53
Shell ramming In courtship results In Immobilization of the female.
In males of G.. berlandlerl the shell ramming of Type One combat ulti
mately determines dominance. In Type One combat the ramming movement
has an upward arc at the end of the forward thrust, to overturn the
other tortoise. The upward arc Is absent In ramming In courtship and
Type Two combat of (5. berlandlerl.
In Type Two combat of £. berlandieri all four legs of the dominant
male are extended and his head Is nearly fully extended and arched. The
subordinate male withdraws his feet and fully or partially withdraws his
head which Is thus lower than that of the dominant male. Similarly,
In courtship the female finally withdraws her head and front feet, but
leaves her rear feet extended. Both the subordinate male In Type Two
combat and the subordinate female In courtship support at least part
of their weight on the plastron, while the dominant male stands on all
four legs.

EXPERIMENTS
The preceding observations were based largely on field work. To
more clearly evaluate the field work,laboratory experiments were designed
to find cues used by Gopherus berlandlerl to distinguish sex In Its own
species. Experimental data were analyzed with nonparametric statistics
because I doubt that they conform to all the assumptions underlying the
appropriate parametric tests, particularly the Interval measurement
scale. With this in mind I used the Kruskal-Wal11s one-way analysis of
variance, and in one case the Chi Square test, to determine the homoge
neity of groups of data, and the Fisher-Exact Probability test to com
pare medians within groups of data.
The Open Square Tests
These experiments were designed to detect a differential investi
gative response by male and female tortoises to other male and female
tortoises and controls. The test tortoise was placed in the large open
square box and male and female tortoises were placed Individually into
the small removable cage as a stimulus. Controls were performed with
the removable cage empty.
The tortoises were tested when the chin glands were actively secre
ting (July 21, 1966; November 5* 1966) and when they were Inactive (April
Up 1967; June 1 1967). The data for tortoises with active chin glands
54

Table 4
Results of the Open Square Experiments
Test
Condition
Males responding to:
Male
Totals
Females responding to:
Female
Totals
Males
Females
Control
Males
Females
Control
Chin glands
active
47-5(6)
142.5(10)
63.0(6)
253.0
71 5(5)
56 5(5)
59 0(9)
187-0
Chin glands
Inactive
59.0(5)
33.0(5)
27.5(5)
119.5
38.0(5)
46 0(5)
39-0(5)
123.0
The scores are the totals of ranked raw scores used In the Kruskal-Wal1 Is analysis of variance.
The numbers In parentheses are replications for the indicated trials, each lasting 24 hours
\ji
KJ1

56
represent the responses of 22 different males and 15 different females
used for a total of 41 trials, each lasting 24 hours.
The trials for tortoises with Inactive glands were performed on 15
different males and females for a total of 30 trials lasting 24 hours
each. The trials were distributed equally between two open square
testing boxes. The scores for the open square tests are shown in Table
4. The analysis of these scores provides the following results:
(1) When the chin glands were active males responded differentially
to males, females, and controls (p<.15); the difference in response to
males and females was not significant; however males tended to respond
more to other tortoises (males and females collectively) than to controls
(p=.20).
(2) Females showed a strong differential response (p<.05) to the
stimuli of males, females, and controls and reacted more to males than
to controls or females (p^.OS).
(3) When the chin glands were Inactive the males showed a strong
differential response (p<.05) to the three stimuli. This response was
greater for other males than for females or controls (p*=.10).
(4) Females showed no differential response when their chin glands
were inactive.
(5) Both male and female tortoises made more responses to the stimu
li when their glands were active than when they were inactive (p<.01).
The Closed Square Tests
Response to Live Animals.-Experiments using live test animals were
designed to test if male and female tortoises could distinguish sex on
the basis of movements of other male and female tortoises. Five

57
different males and females were used for a total of fifteen trials.
The live tortoises used as stimuli were confined in a sealed glass
aquarium which was placed in the small, removable cage (Fig. 3)- Thus
a response to the animals would have to be based on something other
than olfactory cues. Controls were the empty aquarium in the removable
cage. While the tortoises were being tested (July, 1967) their chin
glands were secreting. Each trial lasted four hours. Experienced gained
from the open square experiments showed that most (90%) of the responses
recorded during a trial were made during the first four hours.
Response to Preserved Test Anima is.-The closed square experiments
using formalIrwpreserved tortoises as a stimulus were designed to detect
any differential response by male and female tortoises to the sight of
other tortoises. The sealed aquarium eliminated odor as a cue and
tortoises preserved in life-like stances eliminated movement as a
possible stimulus. This experiment therefore tested external morphology
as a clue to sex determination. The tortoises were tested when their
chin glands were active (July and August, 1967). Each trial lasted four
hours and the controls were empty aquaria. The test tortoises consisted
of five different males and females used for a total of fifteen trials.
Table 5 shows the scores of the closed square experiments. Analysis
of these scores provide the following results:
(1) The males showed no significant ability to differentiate between
males, females, and controls (Table 5) when movement or external morpho
logy were the stimuli (Fig. 10).
(2) Females reacted more (p <.15) to moving tortoises than to the
controls but on the basis of external morphology did not distinguish
between males, females, or controls.

Table 5
Results of the Closed Square Experiments
Test
Males responding to:
Male
Fema1es
responding to:
Female
Condition
Males
Females
Control
Totals
Males
Females
Controls
Totals
Live Tort.
in Test Cage
38.0(5)
*+7.0(5)
32.0(5)
117.0
51.0(5)
45(5)
20(5)
116.0
Preserved
tort, in
*+3-0(5)
37.0(5)
68.0(7)
148.0
54.5(6)
54.5(6)
41.0(5)
150.0
Test Cage
The scores are the totals of ranked raw scores used In the Kruskal-Wal1 Is analysis of variance.
The numbers In parentheses are replications for the indicated trials, each lasting four hours
vn
CO

Table 6
Results of the Cloaca Scent Tests
Responses of Males to Cloaca
Scent of:
Responses to Females to
Scent of:
Males
Females
Controls
Males
Fema1es
Controls
66.5(6)
51.0(6)
53-5(6)
86.5(6)
44.5(6)
40 0(6)
The scores are the totals of ranked raw scores used In the Kruskalj^Wal 1 Is analysis of variance.
The members In parentheses are replications for the indicated trials, each lasting twenty-four
hours.
vn
vo

60
The Cloaca Scent Tests
The ability of male and female tortoises to distinguish sex on the
basis of cloaca odor was evaluated by comparing their responses to
cotton swabs which had been smeared with cloacal material from both
sexes. Controls were clean cotton swabs. Jar positions were adjusted
so that male, female, and control swabs appeared an equal number of
times at each station (Table 6). The Jars were washed after each trial.
The tests were performed from October 15, 1966 through November 10, 1966.
Each trial lasted twenty-four hours. A total of 20 females and 22 males
were used.
Male Gopherus berlandlerl were unable to distinguish between male,
female, and control swabs. The females did not respond equally to all
three test items (p<.02) but responded more to male cloaca scent than
to female cloaca scent (p=.025).
Hormone Injections
Efforts to facilitate tortoise reactions In laboratory situations
and to observe possible effects of hormones on the chin glands were per
formed by subcutaneous injections of various hormones.
On March 11, 1967 three pairs of healthy male tortoises of approxi
mately the same size were selected, one member of each pair was injected
with 20 mg. of testosterone phenylacetate. The dosage was extrapolated
from Evan's (1951) work on Chrysemys (then Pseudemvs) scrlpta troost 1
on the basis of carapace length. One pair remained in the outdoor pen,
another pair was put In an indoor pen on a 24-hour day, and the third
pair put In an Indoor pen on a five-hour day. By 14 March the chin glands

61
of the experimental tortoise on the five-hour day were enlarged and secre
ting. The glands of the experimental tortoise kept In the outdoor pen
produced some secretion and were somewhat enlarged. The chin glands of
the experimental tortoise kept on the 24-hour day, and those of all
the controls did not produce a secretion or become enlarged. In the
outdoor pen some pushing not clearly definable as Type One or Type Two
combat was Initiated by two Injected males with some of the noninjected
tortoises.
These results Indicate that In the male the chin gland's activity
Is influenced by the concentration of the male sex hormone and changes
in day length.
Injections of 25 mg. of progesterone In adult females and 20 mg. of
testosterone In adult males when the glands of both sexes were active
(July, 1967) resulted in no observable change in the condition of their
chin glands or behavior. Injections of 50 mg. of thyroxine in males and
females seemed to stimulate appetite.
Investigative activity on the part of males and to a lesser extent
females can be elicited when small amounts of both testosterone
phenylacetate or progesterone are placed in front of the tortoise's nose.

DISCUSSION
Mating In Gopherus berlandierl is divided Into four major stages
(Table 2) during which sexual discrimination Is accomplished. Little
Is known of sex and species discrimination In other tortoises. Several
species are sympatrlc, and closely related sympatric animal populations
are often segregated by species specific mating behavior. Mating be
havior under any circumstances involves sexual discrimination. Mating
behavior In sympatrlc populations Is therefore made even more complex
by the additional problem of species Identification.
The behavioral elements (Table 2) comprising the courtship of
Gopherus berlandierl differ in two major respects from those of G.
polyphemus (Table 3); the initiation of courtship the female of G.
poiyphemus and the different regions of the female's shell bitten by the
male. In the early stages of courtship females of (5. polyphemus
approach males, a behavior I have never observed in female (5. berlandierl.
However to state that the female G. berlandieri plays a passive role In
courtship is incorrect. The experimental results (Table 4) show that
for J3. berlandieri: (1) females respond more to males than to females
or controls during the breeding season (approximately that period when
the chin glands are actively secreting) and, (2) only females can dis
tinguish males from females by cloaca scent.
Observations of courtship in (5. polyphemus are based on tortoises
from populations typical In that Individuals construct burrows and
62

63
maintain more or less well-defined territories. (Auffenberg, 1966-a;
in press). The individual members of such populations occupy more or
less mutually exclusive areas in which contact with other tortoises is
probably greatly restricted. Individuals must leave their normal acti
vity area In search of other tortoises during the breeding season. Under
these circumstances females would be more aggressive in seeking males
than would females from nomadic populations. An active response by fe
males to threat and courtship displays of males has been postulated as
one evolutionary result of territorial behavtor (Bastock, 1967).
All the G. berlandieri were from nomadic populations of the
Jackass Prairie near Brownsville, Texas. These individuals have rela
tively large activity ranges and females often meet males in their daily
movements. The experimental evidence suggests that the ability of fe
male 6. berlandieri to detect males by confrontations (Table 4), cloacal
scent (Table 6), and her tendency to be attracted to moving tortoises
of either sex (Table 5) ensure her discovery by males during the breeding
season. The differences in aggressiveness between female £. berlandieri
and female £. polyphemus can be explained In terms of the different
ecology of the two species.
The males of Gopherus polyphemus and G. berlandieri consistently
bite different areas of the female's shell during courtship. Male G_.
berlandieri bite the female's head, front legs, and, most consistently,
the upper part of the female's carapace In the region of the nuchal bone.
This biting becomes Increasingly forceful during courtship. Biting by
males of polyphemus differs In two Important respects from that in
G. berlandieri in that it is concentrated on the female's guiar pro
jection and Is less forceful. I interpret the biting of the female by

64
the male to be a highly specific behavior of considerable Importance in
the courtship of the two species. Differences in the courtship behavior
could well stem from Isolating mechanisms resulting from Pleistocene
sympatry. That the courtship of the two groups Is mutually exclusive,
possibly as a result of this sympatry (Fig. 1) Is supported by: (l) Hy
bridization between species of the agasslzl group that produced living
offspring (Householder, 1950; Woodbury, 1952); (2) On several occasions
I placed males and females of G. berlandlerl. £. agasslzl and £.
polyphemus together both In Indoor and outdoor pens and the only court
ship observed was between males and females of the same species, or
between members of the agasslzl group (G. agasslzl and G_. berlandlerl).
The laboratory experiments show that Gopherus berlandlerl consis
tently makes heterosexual preferences only when chin glands are
actively secreting (Table 4). The chin gland's secretion consisted of
aromatic compounds, the compositions and concentrations of which are
different In males and females (Rose, Weaver, Drotman, ms). In males
the activity of this gland Is probably controlled, In part, by testosterone
level and day length.
Sexual discrimination In £. berlandlerl may be shared by both sexes.
The female's ability to distinguish males from females by cloaca) scent
Is one such discriminatory ability. Exactly how a male determines if a
tortoise Is a female Is not known, but the experiments show that males
cannot recognize females by cloacal scent, external morphology, or move
ment. This suggests that sexual discrimination by the male rests in
part, with the secretion of the chin glands. That the glands enable the
male to distinguish the sexes Is suggested by a comparison of the results
of the open square experiments with respect to chin gland activity

65
(Table 4). The males react to females when chin glands are active in
both sexes, and to males when the glands are inactive in both sexes.
Females react to males when the glands of both sexes are active, and do
not discriminate when glands are inactive. These data and the field
observations of courtship and combat suggest a means by which sexual
discrimination is accomplished in G,. berlandier!. Attribute to the
female's glands substances A and 8, and to the male's glands substance
A. These symbols represent the sexual differences in the chemical com
position of the gland's secretion. During the latter part of the
trailing phase of courtship (Stage 1, Table 2) or the first part of
phase two (Stage 2, Table 2)-the stimulus of scents A and B signals
the male that the other tortoise is a female. Since a stage resembling
trailing (Stage 1, Table 2) occurs in Type Two combat between males,
sexual identification probably occurs In stage two when close contact
occurs. The female's ability to detect the male by cloaca scent (hence
also perhaps by feces), and her positive response to moving tortoise
like objects provide an orientation mechanism by which she is discovered
by males. In G,. berlandlerl intromission Is accomplished only if the
female cooperates by presenting, behavior not seen in Type two combat
between males, and by partially extruding her cloaca toward that of the
mounted male. Failure of the female to distinguish another tortoise as
a male by cloacal scent results in her failure to present, thus pre
venting intromission. Sexual discrimination may be made Independently
in both sexes In stage two of courtship.
Initial meetings of potential breeding pairs are due to, (1) a
biased attraction of females for moving tortolse-1Ike objects and, (2)
a probable high but random investigative behavior of males. Sexual
discrimination does not occur until stage two of courtship.

66
Males respond more to males than to females when chin glands are
inactive (Table 4). This conclusion Is supported by: (1) Combat has
been observed between captive adult males when the glands were inactive,
and among Juveniles when the glands are presumably Inoperative (at
least no reaction Is observable and the glands are not seasonally en
larged); the only female combat I have observed was between two sub
adults; (2) most of the combat observations In the Brownsville area and
from captive specimens from Brownsville, are from relatively early In
the reproductive season when the glands are not active; (3) the chin
glands of Individuals In the Brownsville populations were not enlarged
until late June or early July, corresponding roughly with the first
widespread observations of courtship; (4) 1 have never observed adult
females ram or otherwise behave aggressively toward adult males.
These observations suggest that a male recognizes a female only when
the chin glands of both are active. Aggressive behavior is characteris
tic only of males. Therefore Type One combat occurs only between males.
If another tortoise assumes a subordinate role, it Is a nonaggressIve
adult male, a juvenile of either sex, or an adult female. If mating
behavior then occurs It will be courtship if the proper chin gland odor
(substance A and B) Is present and Type Two combat if the proper chin
gland odor Is not present.
I have never observed males present, or any males mounting males
In any combat In (3. berlandierl. In stage two of courtship the female
presents and mounting occurs. This suggests that, (1) presentation
may release mounting and copulatory behavior and that, (2) the identi
fication of a tortoise as a female by a male may also be partly depen
dent on such a releaser. In this case the chin gland secretion would not

67
be the only means of sexual Identification In the species; behavior
would also serve as a means of sex Identification.
Head movements are known to be visual signals In Geochelone
carbonaria and _G. dentIculata (Auffenberg, 1965). I do not believe that
a visual sex or species-spec IfIc signal Is the primary role of head
bobbing In (5. berlandlerl because It Is most frequently performed by
the male during the trailing stage of courtship when he Is out of the
female's visual field, males often bob at females In pallets when the
male Is also out of the female's visual field, and males may scarcely
bob at all, and then erratically, when confronting a female. Head
bobbing In Gopherus berlandlerl. and probably the other species of
Gopherus Is primarily an olfactory movement. In Gopherus head bobbing
has species-specific differences (Fig. 8), but no known visual discrimi
natory function. This suggests that In Gopherus head bobbing Is In an
early stage of emancipation to a visual signal function from a movement
attending olfaction. This Is supported In part by Information gained
watching a male captive G_. agassIzl who bobbed at a female G.. berlandlerl
when she turned her head toward him. Therefore bobbing In all species
of Gopherus may not have the same role. The type of head movements used
by the South American Geochelone In species discrimination Is the same
as that used by them In olfaction: The head movements as visual signals
In Geochelone are derived directly from the head movements associated
with olfaction.
While head bobbing may be Insignificant as a visual signal In
Gopherus. the angle a tortoise Inclines Its head reflects a dominant
or subordinate status and may serve as a visual Indicator to other
tortoises. In combat dominant males of Gopherus berlandlerl Incline

68
their heads higher than do subordinate males. Dominant males of G.
polyphemus keep their heads higher than subordinate males during con
frontations. In courtship the head of an aroused male of (3. berlandlerl
Is fully outstretched and Inclined In a high arch. A sexually aroused
male would therefore automatically display a dominant head position
and Intimidate other males less highly motivated sexually.
The question of dominance Is central to successful courtship or
combat behavior. The significance of the similar behavior used to
establish dominance In both courtship and combat, particularly as seen
In G. berlandlerl. Is that It Indicates that the behavioral units of
courtship are derived from those of combat. One of the major differences
between the courtship and combat of £. berlandlerl and JG. polyphemus Is
that while neither species engages In Interspecific courtship with the
other In captive situations, males of G. berlandlerl and both sexes of
£. polyphemus have been observed to participate In Interspecific combat
with Individuals of the other species of Gopherus as well as with In
dividuals of species of other genera. Hatchlings of Gopherus aqasslzl
(Miller, 1932) ram one another, and I have observed young G¡. polyphemus
up to a year of age do the same. I have seen no attempts to assume a
copulatory position In species of Gopherus this young. Combative
behavior In adults may arise from many situations, such as limited food,
space, or shelter. Specles-speclfIc courtship behavior apparently arises
In tortoises only when sympatry with other turtle or tortoise species
confuses species Identification. Tortoise species with a long history
of allopatry are notorious for their lack of species discrimination
during the breeding season. Footballs, rocks, or any tortoise-resembling
object appeal equally to the nondiscriminating maletortolse.

69
In a much larger sense courtship Is a block of behavioral elements
which seems to have been displaced or emancipated from phylogenetlcally
older functions as a form of combat, specifically, In this case, Type Two
combat. Displacement activity is abundantly reported for many groups
of animals. Basically it consists of a behavior which is emancipated
from one set of causal factors to another set (Blest, 1963; Tinbergen,
1952). Displacement activity largely consists of comfort movements and
appears to arise In the presence of Intense conflicting drives (Hess,
1965). The behavior of female tortoises In the trailing stage of
courtship (Stage l, Table 2) or of a nonaggressIve male In the early
stages of Type Two combat appears to be an example of displacement
activity. In courtship, In particular, grazing by the female during the
trailing stage could well be a comfort movement. Head bobbing In
courtship or combat is another example of displacement behavior since
Its origin Is probably In movements to facilitate olfaction. At least
In one Instance head bobbing as a visual signal has been demonstrated
to be derived from head bobbing associated with simple olfaction
(Auffenberg, 1965).

BIBLIOGRAPHY
Agassiz, A. 1857. Contributions to the natural history of the United
States of America, Vol. 1. Boston: Little Brown and Co.
Auffenberg, W. 1964. A redefinition of the fossil tortoise genus
Stylemvs Leldy. J. Paleo., 38(2): 316-324.
1964. Notes on the courtship of the land tortoise Geochelone
travancorca (Boulenger). J. Bombay Nat. Hist Soc. 61(2):
247-253.
1965. Sex and species discrimination In two sympatrlc South
American tortoises. Copela (3): 335*342.
1966a. On the courtship of Gopherus Polyphemus. Herp. 22
orrn3-n7.
1966b. The carpus of land tortoises (Testudlnlnae). Bull.
Fla. State Mus. 10(5): 159*191.
Tortoise behavior. BSCS pamphlet. In press.
and W. G. Weaver, Jr. The ecological behavior of Gopherus
berlandlerl In southeastern Texas. Bull. Fla. State Mus. In press.
Bastock, Margaret. 1967- Courtship: an ethologlcal study Aldlne
Publishing Co., Chicago, pp. 220.
Beltz, R. E. 1954. Miscellaneous observation on captive Testudlnlnae.
Herp. 10: 45-47.
Blest, A. D. 1963. The concept of ritualization. In: Current pro
blems In animal behavior. W. H. Thorpe and 0. L. Zanwl11 (ed),
Cambridge Unlv. Press., pp. 102-124.
Brumwell, M. J. 1940. Notes on courtship of the turtle, Terrapene
ornata. Trans. Kansas Acad. Scl., 43: 391*392.
Camp, C. L. 1916. Notes on the local distribution and habits of amphi
bians and reptiles of southeastern California In the vicinity of
the Turtle Mountains. Unlv. Calif. Publ. Zool., 12(17): 503*544.
Campbell, Howard W. and William E. Evans. 1967. Sound production in
two species of tortoises. Herp., 23(3): 204-209.

Carpenter, C. R. 1962. Societies of monkeys and apes. In: Primate
social behavior. Charles H. Southwlch (ed), 0. Van Nostrand
Company, Inc. pp. 24-51.
Car, Archie. 1952. Handbook of turtles. New York: Comstock Publi
cation.
DeSola, R. 1930. The Llebesplel of Testudo vandenburghl. a new name
for the mid-Albemarle Island Galapagos tortoise. Copela (3): 79"
80.
Dltmars, R. L. 1910. Reptiles of the world. New York: Sturgis
Walton Company.
Doumerque, F. 1899. Essal sur la Faune erpetologlgue de l'Oranle.
Soc. Geogr. Arch. Ovan, 19: 197-260, 501-502.
Eglls, A. 1962. Tortoise behavior: a taxonomic adjunct. Herp. 18
(1): 1-8.
1963. Nesting of a parrot-beaked tortoise. Herp. 19(1):
6(j-68.
Evans, L. T. 1951. Effects of male hormone upon the tall of the slider
turtle Pseudemys scrlpta troost 11. Science 114(2959): 277-279.
Fltzslmons, V. 1935. Notes on a collection of reptiles and amphibians
made In the southern Kalahari, Buskmanland and Great and Little
Namagua land. Annals Transvaal Mus., 15: 519550.
Grant, Chapman 1936. The southwestern desert tortoise, Gopherus
agassIzl1. Zoologlca 21(4): 225-229.
1946. Data and field notes on the desert tortoise (Gopherus
agasslzl). Trans. San Diego Soc. Nat. Hist. 10: 399"402.
___________ I960. Differentiation of the southwestern tortoises (genus
Gopherus) with notes on their habits. Trans. San Diego Soc. Nat.
Hist. 12: 441-448.
and C. R. DeSola. 1934. Antillean tortoises and terrapins:
distribution, status and habits of Testudo and Pseudemys. Copela
(2): 73-79.
Hamilton, Rodgers D. 1944. Notes on the mating and migration of
berlandlers turtle. Copela, 1942 (1): 62.
Hay, Oliver P. 1908. The fossil turtles of North America. Spec.
Publ. Carneg. Inst., Wash., 75: 268 pp.
Heller, Edmund. 1903. Papers from the Hopkins Stanford Galapagos
Expedition 1898-99, XVI. Reptil la. Proc. Wash. Acad. Scl., 5:
39-98.
Hess, E. H. 1965. Ethology: an approach toward the complete analysis
of behavior. In: Readings In animal behavior. Holt, Rinehart
and Winston.

Householder, V. H. 1950. Courtship and coition of the desert tortoise.
Herp.,6: 11.
legler, J. M. and R. C. Webb. 1961. Remarks on a collection of Bolson
tortoises. Gopherus flavomarglnatus. Herp. 17(1): 26-37.
Miller, Loyce. 1932. Notes on the desert tortoise (Testudo agasslzlI).
Trans. San Diego Soc. Nat. Hist. 7: 187-208.
Mykytowycz, R. 1965. Further observations on the territorial functions
and histology of the submandibular (chin) cutaneous glands In the
rabbit. Animal Behav. 13(4): 440-412.
Nichols, Una G. 1953. Habits of the desert tortoise, Gopherus agassizll.
Herp. 9(2): 65-69.
1957. The desert tortoise In captivity. Herp. 13: 141-144.
Nikolskii, A. M. 1915. Fauna of Russia and adjacent countries, Vol. 1,
Reptiles. Zool. Mus. Russ. Cad. Sc!., pp. 1-532.
Rose, Francis L., W. G. Weaver, Jr., and Robert B. Drotman. Preliminary
analyses of the chin glands of Gopherus. (ms).
Rose, Walter. 1950. The Reptiles and Amphibians of Southern Africa.
Procter: Cape Town.
Siegel, Sidney. 1956. NonparametrIc statistics for the behavioral
sciences. McGraw-Hill.
Smith, H. and S. 0. Brown. 1946. A hitherto neglected Integumentary
gland in the Texan tortoise. Proc. Texas Acad. Sci. 30: 45.
Snedlgar, R. and Rokosky, E. J. 1950. Courtship and egg laying of
captive Testudo dentlculata. Copela (I): 46-48.
Taylor, E. H. 1933. Observations on the courtship of turtles. Unlv.
Kansas Sci. Bull. 21: 269-271.
Tinbergen, N. 1952. Derived activities; their causation, biological
significance, origin and emancipation during evolution. Quart.
Rev. Bio. 27: 1-32.
Van Denburgh, J. 1914. The gigantic land tortoises of the Galapagos
archipelago. Proc. Calif. Acad. Sci., 2(1): 203374.
Watson, George E. 1962. Notes on copulation and distribution of
Aegean land tortoises. Copela (2): 317321.
Wermuth, H. and R. Mertens. 1961. Schi1dkroten, Krokodlle, Brucke-
nechson. Veb Gustav Fischer Verlag, Jena.
Woodbury, A. M. 1952. Hybrids of Gopherus berlandlerI and G. agasslzl.
Herp., 8: 33-36.
Woodbury, A. M. and Hardy R. 1948. Studies of the desert tortoise
Gopherus agasslzlI. Ecol. Monogr. 18: 145-200.

BIOGRAPHICAL SKETCH
William Glenn Weaver, Jr.twas born August 14, 1936, at Tampa,
Florida. In August, 1954, he was graduated from Robert E. Lee High School
In Jacksonville, Florida. From 1954 until 1958 he served In the United
States Air Force. In 1959 he enrolled In Jacksonville University,
Jacksonville, Florida, where he received the degree of Bachelor of Science
In June, 1962. He enrolled In the Graduate School of the University of
Florida In June, 1962, and worked as a graduate assistant in the Florida
State Museum until June, 1964, when he received the degree of Master of
Science. From June, 1964, until the present time he has pursued his work
toward the degree of Doctor of Philosophy. He served as a teaching assis
tant in biology from September, 1965, until December, 1966, and as an
Interim Instructor In biology for the University of Florida from January,
1967, until August, 1967. He Is presently an instructor at Santa Fe
Junior College in Gainesville, Florida.
William Glenn Weaver, Jr.,is married to the former Margarette Annette
Plaster and is the father of two children. He is a member of the American
Society of Ichthyologists and Herpetologists, The Herpetologists League,
American Association for the Advancement of Science, and Phi Sigma.

This dissertation was prepared under the direction of the chairman
of the candidate's supervisory committee and has been approved by all
members of that committee. It was submitted to the Dean of the College
of Arts and Sciences and to the Graduate Council, and was approved as
partial fulfillment of the requirements for the degree of Doctor of
Philosophy.
December 19, 1967
Dean, Graduate School
Supervisory Committee:



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FILES


Householder, V. H. 1950. Courtship and coition of the desert tortoise.
Herp.,6: 11.
legler, J. M. and R. C. Webb. 1961. Remarks on a collection of Bolson
tortoises. Gopherus flavomarglnatus. Herp. 17(1): 26-37.
Miller, Loyce. 1932. Notes on the desert tortoise (Testudo agasslzlI).
Trans. San Diego Soc. Nat. Hist. 7: 187-208.
Mykytowycz, R. 1965. Further observations on the territorial functions
and histology of the submandibular (chin) cutaneous glands In the
rabbit. Animal Behav. 13(4): 440-412.
Nichols, Una G. 1953. Habits of the desert tortoise, Gopherus agassizll.
Herp. 9(2): 65-69.
1957. The desert tortoise In captivity. Herp. 13: 141-144.
Nikolskii, A. M. 1915. Fauna of Russia and adjacent countries, Vol. 1,
Reptiles. Zool. Mus. Russ. Cad. Sc!., pp. 1-532.
Rose, Francis L., W. G. Weaver, Jr., and Robert B. Drotman. Preliminary
analyses of the chin glands of Gopherus. (ms).
Rose, Walter. 1950. The Reptiles and Amphibians of Southern Africa.
Procter: Cape Town.
Siegel, Sidney. 1956. NonparametrIc statistics for the behavioral
sciences. McGraw-Hill.
Smith, H. and S. 0. Brown. 1946. A hitherto neglected Integumentary
gland in the Texan tortoise. Proc. Texas Acad. Sci. 30: 45.
Snedlgar, R. and Rokosky, E. J. 1950. Courtship and egg laying of
captive Testudo dentlculata. Copela (I): 46-48.
Taylor, E. H. 1933. Observations on the courtship of turtles. Unlv.
Kansas Sci. Bull. 21: 269-271.
Tinbergen, N. 1952. Derived activities; their causation, biological
significance, origin and emancipation during evolution. Quart.
Rev. Bio. 27: 1-32.
Van Denburgh, J. 1914. The gigantic land tortoises of the Galapagos
archipelago. Proc. Calif. Acad. Sci., 2(1): 203374.
Watson, George E. 1962. Notes on copulation and distribution of
Aegean land tortoises. Copela (2): 317321.
Wermuth, H. and R. Mertens. 1961. Schi1dkroten, Krokodlle, Brucke-
nechson. Veb Gustav Fischer Verlag, Jena.
Woodbury, A. M. 1952. Hybrids of Gopherus berlandlerI and G. agasslzl.
Herp., 8: 33-36.
Woodbury, A. M. and Hardy R. 1948. Studies of the desert tortoise
Gopherus agasslzlI. Ecol. Monogr. 18: 145-200.


50
Pominance-subordlnance.-Pom 1 nance relationships are clearly demon
strated by the relative postures of the tortoises. The dominant tor
toise supports Its weight on all four of Its extended legs. He may
walk around the other tortoise, stopping often to smell his rear legs.
The submissive tortoise holds his head lower to the ground, with his neck
partially extended. If the dominant tortoise continues investigative
activity, the submissive tortoise positions himself at an angle of
approximately 45 to the dominant tortoise and he maneuvers so that one
side (either side) is always presented to the front of the dominant
individual. Such maneuvering is done with the rear legs and, pivoting
on the anterior portion of the plastron, the front legs continue to be
withdrawn. After one to two minutes of this behavior the more active
dominant individual will turn away, apparently no longer Interested In
the other tortoise. Pominance can be demonstrated by placing a small
amount of food In the pen with the two tortoises; the dominant tortoise
inhibits feeding by a subordinate tortoise.
The males of several tortoise and turtle species engage in shell
ramming during combat and for immobilizing the female prior to copula
tion (Auffenberg, 1964; Brumwel, 1940; Taylor, 1933; Nikolskii, 1915;
Hamilton, 1944). Carr (1952) reported ramming between males of G.
polyphemus; however, 1 observed none In these tests. However, observa
tions made in the spring and summer included ramming between males of
_G. polyphemus. and males of 6. polyphemus ramming males of Geochelone
elephantopus and (5. pardal is. Ramming in Gopherus berlandieri has been
discussed earlier in this paper.
The presence of a distinct dominant-submissive relationship in
Gopherus suggests that such behavior is species-specific. It is


Table 6
Results of the Cloaca Scent Tests
Responses of Males to Cloaca
Scent of:
Responses to Females to
Scent of:
Males
Females
Controls
Males
Fema1es
Controls
66.5(6)
51.0(6)
53-5(6)
86.5(6)
44.5(6)
40 0(6)
The scores are the totals of ranked raw scores used In the Kruskalj^Wal 1 Is analysis of variance.
The members In parentheses are replications for the indicated trials, each lasting twenty-four
hours.
vn
vo


13
Figure 5
External view of actively secreting chin glands, G, of a male Gopherus
berlandlerl.


14
The closed square.-Both live and preserved tortoises were used as
stimuli to test the hypotheses that male and female tortoises respond
equally to the sight and movement of other male and female tortoises.
The closed square apparatus included that of the open square, but with the
addition of an aquarium placed Inside of the small, removable cage
(Fig. 3). The top of the aquarium was sealed with a plastic bag fitted
around a wood frame attached to the top of the aquarium. Air was provided
to the animal by means of a long plastic hose.
The scent chamber."A metal bottomed cage (Fig. 4) was used as a
chamber In which reaction to scents was tested. Glass jars with wire
fronts were recessed Into the front wall of this chamber. One Grayson-
Statler sensor was connected to the wire front of each of the jars.
Samples of potentially important scent producing material was placed in
the jars. A circuit was closed when a tortoise's nose touched the wire
front of the jars.
Hormone injections.-Thyroxine, progesterone, and testosterone were
injected subcutaneously to certain individuals In an effort to stimulate
courtship or combat behavior. Injections of these hormones were made
to also evaluate their role in the functioning of certain glands charac
teristically appearing on the chins of the species of Gopherus (Fig. 5)
The glands, described later, are believed to influence courtship and com
bat behavior In Gopherus.
Photographs.-Photographs were made of tortoises engaged In various
aspects of courtship and combat behavior. Both 8-mm and 16-mm motion
picture film was used. Numerous 35~mm photographs were made, particularly
In the field. The motion pictures and still photographs were used to eval
uate the type and extent of each behavioral element occurring In courtship
and combat behavior.


56
represent the responses of 22 different males and 15 different females
used for a total of 41 trials, each lasting 24 hours.
The trials for tortoises with Inactive glands were performed on 15
different males and females for a total of 30 trials lasting 24 hours
each. The trials were distributed equally between two open square
testing boxes. The scores for the open square tests are shown in Table
4. The analysis of these scores provides the following results:
(1) When the chin glands were active males responded differentially
to males, females, and controls (p<.15); the difference in response to
males and females was not significant; however males tended to respond
more to other tortoises (males and females collectively) than to controls
(p=.20).
(2) Females showed a strong differential response (p<.05) to the
stimuli of males, females, and controls and reacted more to males than
to controls or females (p^.OS).
(3) When the chin glands were Inactive the males showed a strong
differential response (p<.05) to the three stimuli. This response was
greater for other males than for females or controls (p*=.10).
(4) Females showed no differential response when their chin glands
were inactive.
(5) Both male and female tortoises made more responses to the stimu
li when their glands were active than when they were inactive (p<.01).
The Closed Square Tests
Response to Live Animals.-Experiments using live test animals were
designed to test if male and female tortoises could distinguish sex on
the basis of movements of other male and female tortoises. Five


16
forearms against the jaw In the region of the glands during courtship.
I have observed similar behavior by male G,. Polyphemus. There Is an en
larged scale on the forearm of all species of Gopherus which Is In the
proper position to be rubbed across the gland. This scale Is best de
veloped In G_. polyphemus and £. flavomarglnatus. An Investigation of
the histological properties of the gland (Fig. 6) and an electrophoretic
analysis of the chin gland secretion was begun In January, 1967 (Rose,
Weaver, and Drotman, ms). Histological examinations showed that they
are functional In both males and females and are similar In structure
to mammalian sebaceous glands. They open to the outside by two or three
ducts, and their secretory activity varies seasonally. In the Browns
ville, Texas, area the glands of adult males begin to enlarge In June,
and by July they are fully enlarged in both adult males and females. In
nature the glands of specimens from this population remain enlarged until
at least December. Most specimens maintained In an Indoor pen on a fif
teen hour day had the glands enlarged until early January. By the end
of January the glands of most of the tortoises had receded. These tor
toises were moved to a large outdoor pen In the Gainesville, Florida,
area on February 1, 1967- The glands of all tortoises had fully receded
a week later and no secretory material could be obtained by gently
squeezing the gland as was possible In previous months.
Electrophoretic analyses of the glandular secretions In species
of Gopherus show that the secretion contains proteins, an esterase, and
three classes of lipids. The lipid classes are triglycerides, fatty
acids, and a steroid, cholesterol, interspecific variation exists in the
number of esterase bands and in the proteins present in the secretion.


21
Biting
Ramming
Table 1 continued
G. berlandlerl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Cherslne angulata (Rose, 1950)
Geochelone dentIculata (Beltz, 195*0
G. elephantopus (Heller, 1903)
Gopherus agassizl (Woodbury and Hardy, 1948; Camp, 1916;
Grant, 19^*6)
G,. berlandlerl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Testudo graeca (Domerque, 1899; Nikolskii, 1915;
Watson, 1962)
Cherslne angulata (Rose, 1950)
Geochelone carbonaria (Auffenberg, 1965)
G. dentfculata (Auffenberg, 1965; Beltz, 1954)
G_. elephantopus (DItmars, 1910; DeSola, 1930)
G.. ocul 1 fera (Fitzsimmons, 1935)
G,. travancorlca (Auffenberg, 1964)
Gopherus agassizl (Nichols, 1953; Miller, 1932)
.G. flavomarqlnatus (Legler and Webb, 1961)
G,. polyphemus (Carr, 1952)
Testudo graeca (Watson, 1962; Nikolskii, 1915)


66
Males respond more to males than to females when chin glands are
inactive (Table 4). This conclusion Is supported by: (1) Combat has
been observed between captive adult males when the glands were inactive,
and among Juveniles when the glands are presumably Inoperative (at
least no reaction Is observable and the glands are not seasonally en
larged); the only female combat I have observed was between two sub
adults; (2) most of the combat observations In the Brownsville area and
from captive specimens from Brownsville, are from relatively early In
the reproductive season when the glands are not active; (3) the chin
glands of Individuals In the Brownsville populations were not enlarged
until late June or early July, corresponding roughly with the first
widespread observations of courtship; (4) 1 have never observed adult
females ram or otherwise behave aggressively toward adult males.
These observations suggest that a male recognizes a female only when
the chin glands of both are active. Aggressive behavior is characteris
tic only of males. Therefore Type One combat occurs only between males.
If another tortoise assumes a subordinate role, it Is a nonaggressIve
adult male, a juvenile of either sex, or an adult female. If mating
behavior then occurs It will be courtship if the proper chin gland odor
(substance A and B) Is present and Type Two combat if the proper chin
gland odor Is not present.
I have never observed males present, or any males mounting males
In any combat In (3. berlandierl. In stage two of courtship the female
presents and mounting occurs. This suggests that, (1) presentation
may release mounting and copulatory behavior and that, (2) the identi
fication of a tortoise as a female by a male may also be partly depen
dent on such a releaser. In this case the chin gland secretion would not


60
The Cloaca Scent Tests
The ability of male and female tortoises to distinguish sex on the
basis of cloaca odor was evaluated by comparing their responses to
cotton swabs which had been smeared with cloacal material from both
sexes. Controls were clean cotton swabs. Jar positions were adjusted
so that male, female, and control swabs appeared an equal number of
times at each station (Table 6). The Jars were washed after each trial.
The tests were performed from October 15, 1966 through November 10, 1966.
Each trial lasted twenty-four hours. A total of 20 females and 22 males
were used.
Male Gopherus berlandlerl were unable to distinguish between male,
female, and control swabs. The females did not respond equally to all
three test items (p<.02) but responded more to male cloaca scent than
to female cloaca scent (p=.025).
Hormone Injections
Efforts to facilitate tortoise reactions In laboratory situations
and to observe possible effects of hormones on the chin glands were per
formed by subcutaneous injections of various hormones.
On March 11, 1967 three pairs of healthy male tortoises of approxi
mately the same size were selected, one member of each pair was injected
with 20 mg. of testosterone phenylacetate. The dosage was extrapolated
from Evan's (1951) work on Chrysemys (then Pseudemvs) scrlpta troost 1
on the basis of carapace length. One pair remained in the outdoor pen,
another pair was put In an indoor pen on a 24-hour day, and the third
pair put In an Indoor pen on a five-hour day. By 14 March the chin glands


COURTSHIP AND COMBAT BEHAVIOR
IN GOPHERUS BERLAND1ERI
By
WILLIAM GLENN WEAVER, JR.
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
December, 1967


FOSSIL HISTORY AND SYSTEMATICS OF GOPHERUS
The earliest known tortoises are represented by fossils from the
Eocene of Africa and North America. The earliest North American genus Is
Stylemys. known from the Eocene (Auffenberg, 1964). The genus Gopherus.
a descendant of Stylemys. Is represented In North America from the Ollgo-
cene to the Recent (Hay, 1908; Auffenberg, 1964). At least as early as
the Irvingtonlan stage of the Pleistocene Gopherus was already divided
Into Its two extant species groups; the polyphemus group, and the agasslzt
group (Auffenberg, 1966b). Gopherus polyphemus of the southeastern United
States and £. flavomarglnatus of north central Mexico comprise the
polyphemus group. Gopherus agasslzl of the southwestern United States
and northwestern Mexico, and G_. berlandierI of southeastern Texas and
northeastern Mexico comprise the agasslzl group (Fig. 1).
Wermuth and Mertens (1961) consider all living Gopherus populations
as subspecies of G_. polyphemus. Most workers (Auffenberg, 1966b; Carr,
1952; Grant, I960) treat each of the four populations as distinct species,
with which I concur.
5


EXPERIMENTS
The preceding observations were based largely on field work. To
more clearly evaluate the field work,laboratory experiments were designed
to find cues used by Gopherus berlandlerl to distinguish sex In Its own
species. Experimental data were analyzed with nonparametric statistics
because I doubt that they conform to all the assumptions underlying the
appropriate parametric tests, particularly the Interval measurement
scale. With this in mind I used the Kruskal-Wal11s one-way analysis of
variance, and in one case the Chi Square test, to determine the homoge
neity of groups of data, and the Fisher-Exact Probability test to com
pare medians within groups of data.
The Open Square Tests
These experiments were designed to detect a differential investi
gative response by male and female tortoises to other male and female
tortoises and controls. The test tortoise was placed in the large open
square box and male and female tortoises were placed Individually into
the small removable cage as a stimulus. Controls were performed with
the removable cage empty.
The tortoises were tested when the chin glands were actively secre
ting (July 21, 1966; November 5* 1966) and when they were Inactive (April
Up 1967; June 1 1967). The data for tortoises with active chin glands
54


33


LIST OF TABLES
Page
1. Behavioral Elements In Tortoise Courtship and Combat 20
2. Stages of Courtship Observed In Gopherus berlandlerl. 31
3. Stages In the Courtship of Gopherus polyphemus 40
k. Results of the Open Square Experiments 55
5. Results of the Closed Square Experiments 58
6. Results of the Cloaca Scent Tests 59
Iv


COURTSHIP IN OTHER GOPHERUS SPECIES
The courtship of Gopherus Polyphemus has been described by Auffenberg
(1966) and differs In several respects from that of G. berlandlerl. In
no Instance have I seen female G.. berlandleri make an Initial approach
to male G,. berlandlerl as occurs In £. polyphemus (Stage 2, Table 3).
Head bobbing Is faster In polyphemus than In berlandleri (Fig. 8).
Ramming of the female by the male Is similar In both species, but the
biting (Stage 3, Table 3) differs In that G,. berlandlerl males have not
been observed to bite the guiar projection of G. berlandleri females.
The courtship is similar In the two species In that during the biting
phase of courtship females of both (5. polyphemus and G_. beriandieri move
backward away from the male in a circular path. (Stage 2, Table 2;
Stage 4, Table 3)
The only reference to courtship or combat behavior in G,.
flavomarginatus is by Legler and Webb (1961). They observed that males
initially assume an aggressive role and that the females did not approach
the male as in the early part of courtship in G. polyphemus. Male and
female (5. flavomarginatus have a tendency to push or crowd tortoises
against an object such as a fence post or rock. In one instance a fe
male £. flavomarginatus crushed a female and on another occasion a male
G. polyphemus against a fence post so forcibly that the shell of the G.
polyphemus was fractured In several places (Francis L. Rose, personal
communication).
41


24
The protein concentration In females of all species of Gopherus Is much
lower than In males. Females of all species of Gopherus had a cathodal
migrating band which was absent in males (Fig. 7).
The courtship and combat of tortoises Is a complex series of behav
ioral Interactions. The particular sequence of these elements vary
Interspecifleally, and In some species some elements are absent. Cer
tain behavioral elements have been recorded frequently enough In differ
ent and unrelated species to imply the existence of a generalized type
of tortoise courtship or combat consisting of common behavioral elements.
Table 1 lists nine behavioral elements of courtship or combat behavior
which are found in species of Gopherus. At present more courtship and
combat behavior Is known for species of Gopherus than for any other
tortoise species Thus Gopherus Is here used as a comparative base in
considering behavior in other tortoise species. Listed in Table 1 are
also other tortoise species for which each of the behavioral units found
in Gopherus berlandleri have been observed.
Head bobbing -This movement is known for most tortoises and is per
formed in a characteristic fashion in different taxa (Eglis, 1962). It
is also one of the most frequently observed movements of tortoises
during courtship and combat. Eglis (1962) recognized that head movements
in tortoises are latolent (lateral) or dirolent (straight). Eglis stated
that the head movement of living species of Gopherus is basically
dirolent. In Gopherus the neck is usually fully extended and the head
is nodded vertically. The action pattern diagrams (Fig. 8) compares the
duration, magnitude, and frequency of the vertical bobbing in three
Gopherus species.


n
A
Figure 3
Closed square apparatus. A, removable cage; B, five gallon aquarium;
C, air tight plastic seal; D, hose providing air to tortoise acting
as stimulus.


Table 4
Results of the Open Square Experiments
Test
Condition
Males responding to:
Male
Totals
Females responding to:
Female
Totals
Males
Females
Control
Males
Females
Control
Chin glands
active
47-5(6)
142.5(10)
63.0(6)
253.0
71 5(5)
56 5(5)
59 0(9)
187-0
Chin glands
Inactive
59.0(5)
33.0(5)
27.5(5)
119.5
38.0(5)
46 0(5)
39-0(5)
123.0
The scores are the totals of ranked raw scores used In the Kruskal-Wal1 Is analysis of variance.
The numbers In parentheses are replications for the indicated trials, each lasting 24 hours
\ji
KJ1


46
and pushed the smaller one around quite a bit. He (Stubby) Mould put
his guiar projection beneath the plastron (mostly In the front) and
begin to lift the other In an apparent attempt to turn It over. Three
or four times, when the smaller tortoise appeared as If It would be
turned over, It would place Its forelImbs over and around the back of
those of "Stubby" and appear to be holding on In order not to be turned
over. Stubby pushed the other tortoise backward several times but most
often Into a bush and could not turn It over due to the resistance of
the bush.
About 7:10 p.m. the two finally came Into an open area during the
combat ("Stubby" pushed the other tortoise Into the open), and during a
time of "combat" when both had their head withdrawn and were pushing on
one another, I flipped the smaller tortoise onto Its back. "Stubby"
then came up to the other tortoise, which was trying to turn back over
and began to bite In on the side (edge) of the shell and left hind foot.
The smaller tortoise turned back over onto its feet and "Stubby" immedi
ately placed Its guiar projection under the side of the shell of the
smaller tortoise and turned it onto Its back again. This time the
smaller tortoise lay motionless and "Stubby" Just looked at it. After
about 30 seconds "Stubby" turned around and walked off. Both were
picked up in order to determine sex. This was about 7:15 a.m. A
circle (on the ground) of about 6' In diameter showed evidence of much
scratching which must have occurred prior to the above observations.
In a large outdoor pen in Gainesville, Florida, combat has been ob
served as early as March 12. In Brownsville, Cameron County, Texas,
local residents also reported tortoise combats as early as March.


% 0
d A,
G. berlandieri


LIST OF FIGURES
Page
1. Ranges of Pleistocene and Recent Gooherus Species 4
2. The Open Square Apparatus 10
3. The Closed Square Apparatus II
4. Scent Testing Chamber 12
5. External View of Actively Secreting Chin Glands of a Hale
Gooherus berlandlerl 13
6. Histological Section of the Chin Gland of a Hale
Gooherus berlandlerl 18
7. Diagrammatic Representation of the Protein Bands In the
Chin Gland Secretion of Gooherus Species 19
8. Action Patterns of Head Bobbing 23
9. Stages of Courtship In Gooherus berlandlerl 33
10. Sexual Dimorphism In Gooherus berlandlerl 35
v


19
B F A
CZ3
CI3 CZ-5 O
CZ3
D +
Figure 7
Diagrammatic representation of the protein bands in the chin gland
secretion of Gopherus species. B, Gopherus berlandieri; F,
f lavomarginatus ; A, G_. agass i z i The females but none of the males
of the living species of Gopherus have a negative protein band.


31
Table 2
Stages of Courtship observed In
Gopherus berlandlerl
Stage
Male
Fema1e
1.
Follows female and occasionally
bobs head
Indifferent to male
Increased vigor of head bobbing,
rate of walking surpasses that
of female
Increases walking speed
2.
Overtakes female, bites her
feet, carapace
Trles to avoid male,
turns away from him,
both describe a circular
pattern
Rams female
Withdraws head and front
feet, rear feet remain
extended
3.
Initial mounting attempts
Remain still, or may
attempt to walk away
Rams and bites If female
tries to walk away
4.
Coition


27
Olfaction In Gopherus is a simple dirolent motion with little of the
vertical component which essentially characterizes head bobbing as seen
in courtship or combat. Thus a distinction exists between the types of
head movements performed when odor is the only stimulus, as opposed to
the head movements seen in the head bobbing of courtship or combat when
factors other than, or in addition to, olfaction are Involved. During
meetings between tortoises head bobbing of the kind observed when food
or feces are examined occur repeatedly. In these true olfactory move
ments, as opposed to head bobbing, the head is directed toward the front
and rear portions of the other tortoise's shell.
Biting.-in Gopherus berlandleri biting occurs in both courtship and
combat. I have never observed biting in the combat of G,. Polyphemus.
It is reported in the combat of £. agassizi (Camp, 1916; Woodbury and
Hardy, 19*+8; Grant, 19*+6). During courtship males of £. berlandierl bite
the females on the head, front legs, and the front edge of the carapace.
As courtship proceeds biting becomes increasingly confined to the ante
rior edge of the female's carapace. Biting also occurs in combat in this
species. Both males may bite one another very forcibly, although I have
never seen Injuries. During the courtship of G,. polyphemus the males
bite the head and front feet of the females, but confine most of the
shell biting to the female's guiar projection and the anterior carapace
edge is not biten. Camp (1916) and Woodbury and Hardy (l9*+8) report
biting In both courtship and combat of G,. agass izi. Eglis (1963) reports
that a courting male Homopus areolatus vigorously bit the head of a fe
male. I have seen female Geochelone elephantopus produce serious
wounds by biting exposed areas of Gopherus po1yphemus, although the
biting was not In a courtship or combat context. Beltz (195*+) reports


39
the female on her right. She turned away from him counter-clockwise and
he followed, still bobbing. He bit the anterior end of her shell and she
withdrew her head and forefeet. By 7:^5 a m. the female was no longer
turning away from the male The male's bites were more forceful, he
grasped, pushed and pulled the female. At 7:50 a.m. he mounted her,
holding his mouth open during copulation I heard no sounds from him,
but both the wind direction and my distance of 30 yards from the pair may
have dampened any vocalization At 7:58 a.m. the female walked out from
under the male He followed her for five or six feet and made a few
slow, low intensity head bobs. The female moved into a pallet, the male
walked away.


METHODS
Field and laboratory studies were performed to Investigate the
courtship and combat behavior of Gopherus berlandleri. The field work,
begun In November, 1963, and completed In October, 1967, represents a
total of 103 days.
It Is difficult to obtain detailed Information In the field to
clarify the sequential behavioral events of courtship and combat behav
ior. These tortoises are nomadic, small, shy, and reach maximum popula
tion densities In relatively thick, thorny brush. Many days were spent
In the field without seeing courtship or combat, yet this paper represents
the most intensive Investigation of tortoise courtship and combat behav
ior publI shed.
Laboratory experiments were designed to analyze behavior sequences,
specifically the nature and Importance of the cues used by £. berlandleri
to distinguish sex In Its own species. I rejected fully the Idea of
making the study entirely experimental. Observations of such complex
behavioral Interactions as courtship and combat made only on captive
animals do not necessarily accurately reflect similar behavior in nature
(Carpenter, 1962). My experiences have shown that tortoises kept together
soon become accustomed to one another with the result that the frequency
of courtship or combat behavior is reduced. Such tortoises evince re
newed courtship or combat behavior when strange Individuals are intro
duced.
8


COMBAT IN GOPHERUS BERLAND1SRI
Combat between males begins before the breeding season and drops
off sharply In frequency before the breeding season Is over. The
following observations are based on three complete and four partial com
bat sequences seen in the field and on many partial sequences observed
among captive tortoises. I have seen combat between captive males kept
In an outdoor pen as early as March and combat has been observed in the
field as late as July.
True combat In Gopherus berlandlerl occurs only between males. I
have seen only one instance of antagonistic behavior between adult
females which Involved only pushing.
Two aggressive males approach each other and ram. One combatant
attempts to overturn the other. One male walks toward another or both
move toward each other. Their heads may be motionless or bobbing
vigorously. At first ramming is mutual. This type of combat In which
both tortoises are Initially aggressive will be called Type One combat.
Another kind of combat, Type Two, occurs between males if one Is clearly
dominant and the other is not aggressive. The dominant tortoise rams
and bites the subordinate one in a series of movements similar to those
In Stage Two of courtship. The dominant male rams and even bites the
subordinate male on the front feet, head, and the same part of the shell
he does on the female during courtship. The subordinate male avoids the
aggressive male by pivoting from the aggressor In the same circular
43


23
A
B
C
SECONDS
0 1
Figure 8
Action patterns of head bobbing. A, Gopherus berlandieri; B,
£. agass i z i ; C, G_. polyphemus .


Table 1 continued
Circular movement of courting pair
Gopherus agasslzl (Woodbury and Hardy, 1948)
polyphemus (Auffenberg, 1966)
Homopus areolatus (Eglls, 1963)
Vocalization Geochelone carbonaria (Snedigar and Rokosky, 1950)
_G. dentIculata (Grant and DeSola, 193*0
G_. elephantopus (Watson, 1962; Heller, 1903; DeSola
1930)
£. oculifera (Fitzsimmons, 1935)
G,. pardal is (Watson, 1962)
Gopherus berlandieri (Householder, 1950)
Testudo graeca (Watson, 1962; Nikolskii, 1915)
Presentation Geochelone elephantopus (DeSola, 1930)
Gopherus agasslzl (Householder, 1950)
(5. polyphemus (Auffenberg, 1966)


Figure 9
Stages of courtship In Gopherus berlandierl. A, trailing; B, ramming; C, biting, D, mounting


2
(3) to search for behavioral elements which have their origin In
mutually exclusive courtship patterns resulting from the prior
sympatry of Gopherus species.


25
Individuals of all species of Gopherus bob their head when objects,
such as food, are being smelled. It also occurs In meetings between two
or more tortoises, and In Gopherus reaches its greatest frequency during
courtship and combat. Bobbing is performed by both sexes, but in court
ship the male bobs more actively than the female. Low intensity bobbing
is performed when the head is not fully extended. Bobbing movements are
often observed when the head is nearly completely retracted, but are
associated with breathing and not olfaction. Head bobbing sequences are
variable in length and have no discernible pattern correlated with either
sex or species in Gopherus. except that the sequences are usually longer
during social Interactions than when food or feces are being smelled.
The bobs performed in courtship and combat are apparently identical.
The only clearly demonstrated function of head bobbing in tortoises is
that of a species recognition in Geochelone carbonaria and (5. denticulata
in which the head movement is lateral (latolent) and has been demonstra
ted to act as a species specific visual signal (Auffenberg, 1965).
Trailing.-This behavioral unit (Stage 1, Table 2) marks the start
of courtship, and to a lesser extent combat. A male trails either a
female in courtship or a male In combat. In Gopherus berlandieri court
ship the male walks behind the female with his head extended, bobbing at
irregular intervals. This behavior occurs at the beginning of courtship
or combat, and may last for nearly an hour. Male G.. berlandieri make no
attempt to overtake the female during this early stage. If she stops,
he stops; the rate of the female's activity influences that of the male.
The male's attention is directed toward the female during this stage,
and his behavior is dependent on hers. She often grazes during this
period. In the courtship of G.. polyphemus the female often walks


40
TABLE 3
Stages In the Courtship of Gopherus polyphemus
(after Auffenberg, 1966)
Stage
Male
Female
1.
Walks In circle and bobs head
Approaches male
2.
Bobs head violently with
approach of female
3.
Bites female on legs and shell
especially guiar projection
4.
First mounting attempts (usually
unsuccessful) followed by more
Moves backward in semi
circle; stretches hind
legs
biting
Radius of semicircle
becomes so small that
female begins to pivot
180 about a central
point
5.
First successful mountings and
finally coition


This dissertation was prepared under the direction of the chairman
of the candidate's supervisory committee and has been approved by all
members of that committee. It was submitted to the Dean of the College
of Arts and Sciences and to the Graduate Council, and was approved as
partial fulfillment of the requirements for the degree of Doctor of
Philosophy.
December 19, 1967
Dean, Graduate School
Supervisory Committee:


COMBAT IN OTHER GOPHERUS
Less is known of combat In other species of Gopherus than of court
ship. Woodbury and Hardy (1948), and Grant (1936) reported that males
of G. aqasslzi charge one another with heads retracted. The contest
consists of attempts by one tortoise to overturn the other using the
guiar projection (Fig. 10) as both a ram and a lever. Miller (1932)
reported that hatchling JS. aqassizl would ram and lunge at each other,
or at an extended human finger.
Legler and Webb (1961) describe fighting In (5. fiavomarqlnatus: I
have observed no combat between captives of this species.
Carr (1952) reports on fights between males and females of Gopherus
polyphemus. I have seen ramming between a captive male and a female of
this species, and observed one particularly ambitious, moderate-sized,
malformed, male (5. polyphemus repeatedly ram subadult Geochelone
eiephantopus and an adult _G. pardal Is. both of which were at least 20
pounds heavier than the (. polyphemus. Some information on combat In
G,. polyphemus was gained by observing confrontations between male
Gopherus polyphemus In the laboratory.
In these experiments each of six adult male tortoises was marked
and kept in rectangular indoor pens. The room housing the pens was
automatically kept on a nine and one-half hour day throughout the
experimental period (February 1, 1965Aprtl 1, 1965). Air temperature
for the entire test period varied from 76 F. to 78 F.
47


*5
bobbed and lunged at the larger one. After a short pause during which
both were Inactive male two walked toward the center of the lawn away
from male one. Male one followed Immediately and bobbed his head In the
direction of male two. The following of male two by male one was exactly
like trailing In courtship (Fig. 9"A). Male two played" the female
role as he nosed Items on the ground and slowed his walk. The chase"
covered about 30 yards and lasted until 10:20 a.m. Then male one over
took and gently bit the anterior end of male two's carapace. Male
two promptly withdrew all appendages. At 10:23 a.m. the chase began anew,
male one tried to overtake male two and bite his head. At 10:25 a.m.
male two found and entered a grassy depression and remained there.
Male one stood behind male two and bobbed his head. Movements by male
two caused male one to ram the exposed rear of male two's shell. At
10:30 a.m. male one still stood behind male two who remained In the
depression. Male one continued to bob his head In the direction of
male two at Irregular intervals. After a short while male one walked
away.
Mr. Kenneth G. Mentocha and Robert L. Snavely, then students at the
Rob and Bessie Welder Wildlife Foundation of Sinton, San Patricio County,
Texas gave an excellent report of type one combat. The combat occurred
Just southwest of Sinton, Texas.
24 July, 1965 6:40 p.m.2 gopher tortoises In combat." Heard
noise in brush about 20' away. Sounded somewhat like a javelina moving
through the brush. Both tortoises were between a Xanthoxylem and a
Ce 111s pallida, pushing each other with the guiar projections. After
about 1 minute they backed off and began to breath heavily as if they
had been at the "fight" a long while and were catching their breath.
After about 30 seconds they again begin the combat. While in close
contact, the smaller tortoise continually bit the front portion of the
carapace of "Stubby."* "Stubby" seemed to be the stronger of the two
*"StubbyThe larger of the 2 tortoises. Had no claws on left
front foot, but a large callous.


30
were desert tortoises, Gopherus agasslzl. Woodbury (1952) later showed
that the male of this pair was actually a Texas tortoise £ berlandlerl.
Campbell and Evans (1967) reported vocalization In Gopherus agasslzl.
but the vocalization was not In a courtship or combat context. Most
reports of vocalization durtng breeding activities suggest that such
sounds are a by-product of the effort expended In copulation. There Is
no Indication that vocalization serves as an auditory signal. However,
the males of Geochelone elephantopus bellow before copulation during the
breeding season (Van Oenburgh, 191*0, and males of £. carbonaria vocalize
prior to copulation (Snedlgar and Rokosky, 1950). This latter observation
was made on what W8S presumed to be Geochelone denticulate. However, the
photo In Snedlgar and Rokosky's paper clearly shows that the tortoises
were G. carbonarla.
Presentation.-A female facilitates successful Intromission and In
higher vertebrates Invites copulation by presentation. In Gopherus
berlandlerl the female holds her body In a characteristic position and
extrudes her cloaca. The female's stance Is one with head and forelimbs
withdrawn and rear limbs partially extended. In Gopherus polyphemus the
presentation Is similar but the female's rear legs seem to be extended
more stiffly than In £. berlandlerl end she may pivot so that the rear
of her shell Is nearest the males head. I have never observed this In
G. berlandlerl.


12
Figure 4
Scent testing chamber. A, pen containing experimental tortoises;
B, jars containing odor stimulus; C, leads to sensor and digital
counters. The chamber Is six feet long at the front, four feet
wide, and one foot high.


18


9
All of the courtship and combat observed In the field suggested that
the front and rear portions of the tortoise were the most likely sources
of olfactory cues relating to sex and species Identification. The most
obvious possible source of odoriferous material at the anterior end of
the tortoise Is the chin glands described in a later section. The
cloaca was considered a probable source of olfactory cues at the posterior
end. Cloacal scent is known to be Important in sex discrimination in
Geochelone carbonaria and (5. dent iculata (Auffenberg, 1965). Movements
of the tortoise were potentially Important visual cues. The experiments
with G. berlandlerI were designed to Investigate the roles of odors from
the cloacal and chin glands and tortoise movement In courtship and combat
behavior. The following testing devices were used in the experiments.
The open square.-These tests were based on the hypothesis that
there Is no differential investigative response between male and female
tortoises to other male and female tortoises and to controls. The test
apparatus (Fig. 2) consisted of an open topped box. The floor was
covered by screen wire. In the center of the box was a felt square. A
small, removable cage with wire sides was placed on rubber mats within
the felt square on the floor of the large box. A Grayson-Statler vacuum-
switch-sensor (Model E4690L) was connected to one of the wire sides of
the small test cage and to a digital counter and a Grayson-Statler drlnk-
ometer panel counter (Models E4690A-I and #370QA, respectively). The
switch operated on a .06 millivolt differential which apparently was not
detectable by the tortoises and assured maximum sensitivity. A circuit
from electrical ground to the sensor was closed when the tortoise,
grounded by the screen on the floor and the water dampened felt, touched
the wire sides of the small cage. The digital counter recorded each
closure of the circuit.


BIOGRAPHICAL SKETCH
William Glenn Weaver, Jr.twas born August 14, 1936, at Tampa,
Florida. In August, 1954, he was graduated from Robert E. Lee High School
In Jacksonville, Florida. From 1954 until 1958 he served In the United
States Air Force. In 1959 he enrolled In Jacksonville University,
Jacksonville, Florida, where he received the degree of Bachelor of Science
In June, 1962. He enrolled In the Graduate School of the University of
Florida In June, 1962, and worked as a graduate assistant in the Florida
State Museum until June, 1964, when he received the degree of Master of
Science. From June, 1964, until the present time he has pursued his work
toward the degree of Doctor of Philosophy. He served as a teaching assis
tant in biology from September, 1965, until December, 1966, and as an
Interim Instructor In biology for the University of Florida from January,
1967, until August, 1967. He Is presently an instructor at Santa Fe
Junior College in Gainesville, Florida.
William Glenn Weaver, Jr.,is married to the former Margarette Annette
Plaster and is the father of two children. He is a member of the American
Society of Ichthyologists and Herpetologists, The Herpetologists League,
American Association for the Advancement of Science, and Phi Sigma.


28
that a male Geochelone dent 1 culata attacked a large Gopherus agasslzl by
biting and ramming its shell and limbs. Biting in tortoise courtship Is
not universal and in at least one species, Geoche1 one t ravancorIca. court
ship occurs without any biting (Auffenberg, 1964).
Ramming.-Ramming of the female by the male during courtship Is
known for all tortoise species whose courtship is well reported. In the
courtship of Gopherus beriandierl the male rams the female's sides more
frequently than other parts of her shell. In combat ramming tends to be
confined to the front ends of the shell of the opposing males. Ramming
In combat often develops into a pushing contest Instead of an exchange
of blows. In either case one male attempts to place his guiar projection
under the plastron of the other and overturn him. This effort results
In a distinctive upward thrust at the end of each ramming movement. This
upward arc is missing from courtship ramming In £. beriandierl. The
ramming motion begtns from a position in which the tortoise is standing
on all four legs. The movement Is Initiated by a slight backward rocking
movement on all four legs, Immediately followed by a sudden forward
thrust in which the head and, to a lesser extent, the front legs are
withdrawn. The withdrawal of the front legs gives a decided downward
angle to the forward thrust. In combat ramming the front legs are ex
tended fully on Impact, thus providing the characteristic upward arc.
In courtship ramming the front legs do not appear to be withdrawn;
there is no upward arc at the end of the forward thrust; the ramming
movement is on a more horizontal plane. In Gopherus. and other species,
ramming has the function of Immobilizing the female In courtship and
the male in combat.


BIBLIOGRAPHY
Agassiz, A. 1857. Contributions to the natural history of the United
States of America, Vol. 1. Boston: Little Brown and Co.
Auffenberg, W. 1964. A redefinition of the fossil tortoise genus
Stylemvs Leldy. J. Paleo., 38(2): 316-324.
1964. Notes on the courtship of the land tortoise Geochelone
travancorca (Boulenger). J. Bombay Nat. Hist Soc. 61(2):
247-253.
1965. Sex and species discrimination In two sympatrlc South
American tortoises. Copela (3): 335*342.
1966a. On the courtship of Gopherus Polyphemus. Herp. 22
orrn3-n7.
1966b. The carpus of land tortoises (Testudlnlnae). Bull.
Fla. State Mus. 10(5): 159*191.
Tortoise behavior. BSCS pamphlet. In press.
and W. G. Weaver, Jr. The ecological behavior of Gopherus
berlandlerl In southeastern Texas. Bull. Fla. State Mus. In press.
Bastock, Margaret. 1967- Courtship: an ethologlcal study Aldlne
Publishing Co., Chicago, pp. 220.
Beltz, R. E. 1954. Miscellaneous observation on captive Testudlnlnae.
Herp. 10: 45-47.
Blest, A. D. 1963. The concept of ritualization. In: Current pro
blems In animal behavior. W. H. Thorpe and 0. L. Zanwl11 (ed),
Cambridge Unlv. Press., pp. 102-124.
Brumwell, M. J. 1940. Notes on courtship of the turtle, Terrapene
ornata. Trans. Kansas Acad. Scl., 43: 391*392.
Camp, C. L. 1916. Notes on the local distribution and habits of amphi
bians and reptiles of southeastern California In the vicinity of
the Turtle Mountains. Unlv. Calif. Publ. Zool., 12(17): 503*544.
Campbell, Howard W. and William E. Evans. 1967. Sound production in
two species of tortoises. Herp., 23(3): 204-209.


7
behavior (W. Auffenberg field notes, 1962, 1963, 1964). Individuals in
Sonora, Mexico, are nomadic all year, wandering in the dry arroyos of the
area. Their shelter consists of a hollow scraped into the base of the
arroyo wall. Further north, in the vicinity of Pima County, Arizona, the
tortoises hibernate in specific winter shelters which are usually enlarged
ground squirrel burrows. They are deep enough so that the posterior end
of the tortoise's shell is flush with the arroyo wall (Auffenberg, in press).
At the extreme northern end of the range, in the area described by Woodbury
and Hardy (1948), the tortoises have different ranges and shelters in
summer and winter. In the summer they move from the upper reaches of the
arroyos onto the flats where they excavate short burrows. In the winter
they hibernate in communal burrows excavated in the arroyo walls. The
seasonal changes of shelter are accompanied by seasonal changes of activ
ity ranges. The summer and winter activity ranges do not overlap.
Gopherus polyphemus usually lives on sandy soil where It constructs
a long, usually nonbranched burrow. New burrows may be constructed by
adult individuals, but normally each individual uses a single burrow
throughout its life. Thus individuals of £. polyphemus have a restricted
activity range (Auffenberg, in press).
Very little is known of G. flavomarqinatus except that it excavates
burrows in the playa soils of the Chihuahuan desert community in Mexico.
The presence or absence of an individual activity range has an
effect on courtship. Tortoises, such as G. polyphemus. which have indi
vidual activity ranges must leave their customary area in order to mate.
Nomadic tortoises, such as G.. berlandieri regularly make contact with
other tortoises. Therefore the portion of courtship involved in finding
the opposite sex might be expected to differ in each of the above circum
stances.


64
the male to be a highly specific behavior of considerable Importance in
the courtship of the two species. Differences in the courtship behavior
could well stem from Isolating mechanisms resulting from Pleistocene
sympatry. That the courtship of the two groups Is mutually exclusive,
possibly as a result of this sympatry (Fig. 1) Is supported by: (l) Hy
bridization between species of the agasslzl group that produced living
offspring (Householder, 1950; Woodbury, 1952); (2) On several occasions
I placed males and females of G. berlandlerl. £. agasslzl and £.
polyphemus together both In Indoor and outdoor pens and the only court
ship observed was between males and females of the same species, or
between members of the agasslzl group (G. agasslzl and G_. berlandlerl).
The laboratory experiments show that Gopherus berlandlerl consis
tently makes heterosexual preferences only when chin glands are
actively secreting (Table 4). The chin gland's secretion consisted of
aromatic compounds, the compositions and concentrations of which are
different In males and females (Rose, Weaver, Drotman, ms). In males
the activity of this gland Is probably controlled, In part, by testosterone
level and day length.
Sexual discrimination In £. berlandlerl may be shared by both sexes.
The female's ability to distinguish males from females by cloaca) scent
Is one such discriminatory ability. Exactly how a male determines if a
tortoise Is a female Is not known, but the experiments show that males
cannot recognize females by cloacal scent, external morphology, or move
ment. This suggests that sexual discrimination by the male rests in
part, with the secretion of the chin glands. That the glands enable the
male to distinguish the sexes Is suggested by a comparison of the results
of the open square experiments with respect to chin gland activity


49
another tortoise. In directed locomotion of a highly motivated tortoise
the neck Is fully extended and walking Is rapid. Nondtrected locomotion
Is slower and the neck Is only partially extended.
Head bobbing.-EglIs (1962) classified head bobbing In Gopherus
as dirolent. This Is the typical head movement performed when smelling
substrate or food. In meetings between two tortoises bobbing usually
occurs first when the tortoises are about two and one-half feet apart.
The function of head bobbing In G_. poiyphemus Is not clear. The
fact that a tortoise is always directed toward another tortoise when
bobbing occurs suggests that a visual cue may be involved. However a
highly motivated tortoise continues to walk toward another tortoise
whether or not reciprocal bobbing or directed locomotion occurs. A
poorly motivated tortoise may not continue bobbing or walking in the
direction of another tortoise if no reciprocal head bobbing or
directed locomotion occurs.
In as much as the behavioral functions of head bobbing are largely
unknown, adjectives such as "contentment," "enthusiastic," "nod of
friendship" used In conjunction with head bobbing can serve only to
make ambiguous otherwise informative reports (Nichols, 1953).
Mutual smelling.-At contact the vertical bobs of both tortoises
assume a large lateral component and finally lose any recognizable
movement pattern. The head and feet of both tortoises are the objects
of smelling. The vertical bobs associated with these smelling move
ments are often Interrupted by a lateral wiping motion directed to the
surface of one of the forelegs. After one to two minutes of mutual
smelling, one of the tortoises becomes more active in all Its movements
than the other.


63
maintain more or less well-defined territories. (Auffenberg, 1966-a;
in press). The individual members of such populations occupy more or
less mutually exclusive areas in which contact with other tortoises is
probably greatly restricted. Individuals must leave their normal acti
vity area In search of other tortoises during the breeding season. Under
these circumstances females would be more aggressive in seeking males
than would females from nomadic populations. An active response by fe
males to threat and courtship displays of males has been postulated as
one evolutionary result of territorial behavtor (Bastock, 1967).
All the G. berlandieri were from nomadic populations of the
Jackass Prairie near Brownsville, Texas. These individuals have rela
tively large activity ranges and females often meet males in their daily
movements. The experimental evidence suggests that the ability of fe
male 6. berlandieri to detect males by confrontations (Table 4), cloacal
scent (Table 6), and her tendency to be attracted to moving tortoises
of either sex (Table 5) ensure her discovery by males during the breeding
season. The differences in aggressiveness between female £. berlandieri
and female £. polyphemus can be explained In terms of the different
ecology of the two species.
The males of Gopherus polyphemus and G. berlandieri consistently
bite different areas of the female's shell during courtship. Male G_.
berlandieri bite the female's head, front legs, and, most consistently,
the upper part of the female's carapace In the region of the nuchal bone.
This biting becomes Increasingly forceful during courtship. Biting by
males of polyphemus differs In two Important respects from that in
G. berlandieri in that it is concentrated on the female's guiar pro
jection and Is less forceful. I interpret the biting of the female by


44
turning pattern of the female described In courtship. The dominant male
was never observed to attempt to mount a subordinate male. Thts type of
combat ends when the subordinate male escapes to a pallet or withdraws
all appendages and remains still. Biting Is not a major component of
Type One combat, in contrast to Type Two combat.
Type One combat occurs when neither male becomes subordinate. Both
males engage In ramming and biting, and both attempt to overturn the
other with their guiar projections. Dominance is apparently established
when one overturns the other, or when one flees the combat area after a
ramming and pushing contest. Evidence of the combat often remains on
the ground In the form of a large circular area in which the soil has
been tramped by the feet and piastra of the combatants. Similar areas
are left after stage two of courtship (Table 2). At the end of Type Two
combat the victorious male holds his head at a higher level than that of
the defeated male. If combat terminates by one tortoise fleeing, the
loser will retreat with its head extended directly in front, and the
winner pursues with its head inclined about 30.
The following account of Type Two combat is taken from my field
notes taken at Slnton, Texas, 3 August, 1965.
Lake Camp at 10:00 a.m.: I observed fighting between two males of
the 34 tortoises kept in the yard. A large male (male one) walked
rapidly from a clear place on the lawn to a fence 10 feet away where
there were three females and a small male (male two). Male one immedi
ately rammed the smaller male and blocked his access to the females.
The male tortoises bobbed their heads when facing one another. The
smaller male two was passive at first and was turned completely twice
around by the rival. After twice being turned around the smaller male


69
In a much larger sense courtship Is a block of behavioral elements
which seems to have been displaced or emancipated from phylogenetlcally
older functions as a form of combat, specifically, In this case, Type Two
combat. Displacement activity is abundantly reported for many groups
of animals. Basically it consists of a behavior which is emancipated
from one set of causal factors to another set (Blest, 1963; Tinbergen,
1952). Displacement activity largely consists of comfort movements and
appears to arise In the presence of Intense conflicting drives (Hess,
1965). The behavior of female tortoises In the trailing stage of
courtship (Stage l, Table 2) or of a nonaggressIve male In the early
stages of Type Two combat appears to be an example of displacement
activity. In courtship, In particular, grazing by the female during the
trailing stage could well be a comfort movement. Head bobbing In
courtship or combat is another example of displacement behavior since
Its origin Is probably In movements to facilitate olfaction. At least
In one Instance head bobbing as a visual signal has been demonstrated
to be derived from head bobbing associated with simple olfaction
(Auffenberg, 1965).


57
different males and females were used for a total of fifteen trials.
The live tortoises used as stimuli were confined in a sealed glass
aquarium which was placed in the small, removable cage (Fig. 3)- Thus
a response to the animals would have to be based on something other
than olfactory cues. Controls were the empty aquarium in the removable
cage. While the tortoises were being tested (July, 1967) their chin
glands were secreting. Each trial lasted four hours. Experienced gained
from the open square experiments showed that most (90%) of the responses
recorded during a trial were made during the first four hours.
Response to Preserved Test Anima is.-The closed square experiments
using formalIrwpreserved tortoises as a stimulus were designed to detect
any differential response by male and female tortoises to the sight of
other tortoises. The sealed aquarium eliminated odor as a cue and
tortoises preserved in life-like stances eliminated movement as a
possible stimulus. This experiment therefore tested external morphology
as a clue to sex determination. The tortoises were tested when their
chin glands were active (July and August, 1967). Each trial lasted four
hours and the controls were empty aquaria. The test tortoises consisted
of five different males and females used for a total of fifteen trials.
Table 5 shows the scores of the closed square experiments. Analysis
of these scores provide the following results:
(1) The males showed no significant ability to differentiate between
males, females, and controls (Table 5) when movement or external morpho
logy were the stimuli (Fig. 10).
(2) Females reacted more (p <.15) to moving tortoises than to the
controls but on the basis of external morphology did not distinguish
between males, females, or controls.


61
of the experimental tortoise on the five-hour day were enlarged and secre
ting. The glands of the experimental tortoise kept In the outdoor pen
produced some secretion and were somewhat enlarged. The chin glands of
the experimental tortoise kept on the 24-hour day, and those of all
the controls did not produce a secretion or become enlarged. In the
outdoor pen some pushing not clearly definable as Type One or Type Two
combat was Initiated by two Injected males with some of the noninjected
tortoises.
These results Indicate that In the male the chin gland's activity
Is influenced by the concentration of the male sex hormone and changes
in day length.
Injections of 25 mg. of progesterone In adult females and 20 mg. of
testosterone In adult males when the glands of both sexes were active
(July, 1967) resulted in no observable change in the condition of their
chin glands or behavior. Injections of 50 mg. of thyroxine in males and
females seemed to stimulate appetite.
Investigative activity on the part of males and to a lesser extent
females can be elicited when small amounts of both testosterone
phenylacetate or progesterone are placed in front of the tortoise's nose.