Title: Behavior and ecology of the rock iguana Cyclura carinata
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 Material Information
Title: Behavior and ecology of the rock iguana Cyclura carinata
Physical Description: ix, 379 leaves : ill., maps ; 28 cm.
Language: English
Creator: Iverson, John B
Copyright Date: 1977
 Subjects
Subject: Marine iguana -- Behavior   ( lcsh )
Lizards -- Turks and Caicos Islands   ( lcsh )
Zoology thesis Ph. D
Dissertations, Academic -- Zoology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by John Burton Iverson III.
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 353-378.
General Note: Typescript.
General Note: Vita.
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Bibliographic ID: UF00098919
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000185664
oclc - 03349845
notis - AAV2250

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BEHAVIOR AND ECOLOGY OF THE
ROCK IGUANA CYCLURA CARINATA


















By

JOHN BURTON IVERSON III


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




























Dedication


To the peoples of the Turks and Caicos Islands, for their

assistance in making this study possible, with the hope that they

might better see the uniqueness of their iguana and deem it worthy

of protection.















ACKNOWLEDGMENTS


I wish to express my sincere gratitude to Walter Auffenberg,

chairman of my doctoral committee, for his constant aid and encourage-

ment during this study. Thanks also are due to the other members of

my committee: John Kaufmann, Frank Nordlie, Carter Gilbert, and

Willard Payne.

I am particularly grateful to the New York Zoological Society for

providing funds for the field work. Without its support the study would

have been infeasible. Acknowledgment is also given to the University of

Florida and the Florida State Museum for support and space for the

duration of my studies.

Of the many people in the Caicos Islands who made this study

possible, special recognition is due C. W. (Liam) Maguire and Bill and

Ginny Cowles of the Meridian Club, Pine Cay, for their generosity in

providing housing, innumerable meals, access to invaluable maps, and

many other courtesies during the study period.

Special thanks are also due Francoise de Rouvray for breaking my

monotonous bean, raisin, peanut butter, and cracker diet with incompar-

able French cuisine, and to Gaston Decker for extending every kindness

to me while on Pine Cay. They enriched my visits to the islands more

th.r. any other tw'o persons. For similar courtesies I also thank George

and iarou Nipanich. I am also indebted to many other Turks and Caicos

islanders for information and help throughout my study.










Don Correll, Bob Anderson, and Walter Auffenberg supplemented my

plant collections and identified most of the plants. Don Buden supplied

a list of birds recorded from the lurks and Caicos Islands. Arthropod

identifications were made by Bob Woodruff (insects), and Martin Muma

(solpugids and scorpions).

Walter Auffenberg and David Auth unselfishly allowed me access to

their Caicos Islands field notes. Diderot Gicca and Tom Wiewandt

generously shared with me their field experiences with other species of

Cyclura. Aerial photography of the study islands was made possible by

Bill and Ginny Cowles. Numerous others have, in one way or another,

added to the successful completion of this work; I apologize for my

failure to acknowledge each one individually.

My wife, Sheila, typed the numerous manuscript drafts, endured

my frequent absences from home, and supported me in many ways during

all phases of the work. All illustrations are the work of the author.

















TABLE OF CONTENTS


ACKNOWLEDGEMENTS .. . . . ........

ABSTRACT . . . . . . . . . .


INTRODUCTION . . .

Purpose . . . . .
Systematic Relationships and
Study Area . . . .
Zoogeographic Relationships.
Materials and Methods .


Distribution.


MORPHOLOGY . . . . . . . . . . . . . .

HABITAT . . . . . . . . . . . . . . .

Climate. .......... . . . . ......
So il . . . . . . . . . . . . . . .
Vegetation . . . . . . . . . . . . .
Burrows . . . . . . . . . . . .

REPRODUCTION . . . . . . . . . . . . . .

Male Sexual Cycle. . . . . . . . . . . .
Female Sexual Cycle . . . . . . . .. .
Courtship and Mating .. . . .
Neszing .. .... ..............................
Eggs, Incubation and Hatching. . . . ... . . ..
Fertility, Prenatal and Natal Mortality .. . . .....
General Seasonal Reproductive Pattern .. . . .....
Reproductive Effort and Strategy .. . . ........


GROW . . . . . . . .

General Pattern . . . .
Factors Affecting Growt . . . .
Longevity . . . ...........
Regeneration . . . . . . .
Comparisons With Other Iguanines . ..

FOOD AND FEEDING ....... . . . .

D ie t . . . . . . . . .


. . . . 1

. . . . 1
. . . . . 2
. . . . . 3
. . . . . 9
. . . . . 10


. . . . 136

. . 136
. . . 7 1
. . 172
. . 172
. . 173

. . 180










Feeding Behavior ....... . . . . ..... 190
Gastrointestinal Tract Anatomy . . . . . . 202
Digestive Efficiency ..... . . . . . . .. 211
Fat Bodies .... . . . . . . . . . 213
Food as a Limiting Factor. . . . . . . ..... 217
Herbivory as a Feeding Strategy. . . ... ...... . . 220

ACTIVITY AND MOVEMENTS . ... ..... . . . . . 224

Locootion . . . . .... ..... . . . . 224
Retreats ...... .. .. . . ....... .. . 225
Activity Cycles. . . ... ..... ... . . . 225

SOCIAL ORGANIZATION. . . . ... . . . . . . . 255

Displays . . . . . . . .. .. . . . . 255
Dominance Relationships. ... . . . . . . . 272

INTERSPECIFIC COACTIONS. . . ... .. . . . . . 286

Natural Cohabitants .. . . . . .. ... . . 286
Introduced Cohabitants ..... . . . . . . 287
Broken Tail Frequency. . . . . . . . . . . 292
Epifauna ....... . . . . . . . . . 298
Endofauna . . . . ...... . . . . . 299

DENSITY AND DEMOGRAPHY .... . . . . . . . 305

Sex Ratio. . . . . . . .. .. ....... ..... . 305
Characteristics of Juvenile Population . . . . ... 305
Characteristics of Adult Populations . . . . .. . 314
Life Tables . . . .. . . . . . . . 328
Life History Strategy. . . . . . . . . .. 332

OUTLOOK. . .................. .... ...... 337

Populations on Turks and Caicos Islands. . . . . ... 337
Basic Lizard Requirements. . . . . . . . 347
Population Control ................ .. . . 349
Conclusions . .. . ............ . .. .. 352

LITER TURE CITED . . . . . . . . .... . 353

IOCGRAPHICAL SKETCH ......... . . . . . .. . 379











Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy


BEHAVIOR AND ECOLOGY OF THE
ROCK IGUANA CYCLURA CARINATA

By

John Burton Iverson III

June, 1977


Chairman: Walter Auffenberg
Major Department: Zoology

The natural history and social behavior of the rock iguana, Cyclura

carinata, was studied during 25 weeks between September, 1973, and June,

1976, on several small cays in the Turks and Caicos Islands, British

West Indies, and in captive enclosures in Gainesville, Florida.

Reproductive cycles were synchronized to climatic cycles. Testes

sizes were maximal in April and May (the end of the dry season).

Vitellogenesis began in January (beginning of the dry season); cvulation

and mating occurred in early May. Courtship was typical of most iguanid

lizards; the mating system was probably primarily monogamous with serial

polygyny among some males.

A single annual clutch of two to nine eggs was laid in early June

in the terminal portion of the female's retreat burrow. Clutcn size was

positively correlated with female size. Clutch weight averaged about

25% of preoviposition weight. Females defended their nest burrows for

several days to several weeks after nesting, but were not territorial

during the remainder of the year. Hatching occurred after approximately

90 days. Neonates averaged 79.8 mm SV and 14.6 gm. Juvenile growth

rate averaged 19 2 mm SV/year. Males reached s-xual maturity at


vii










approximately 220 mm SV and 375-475 gm, at an age of about seven years;

females, 185-200 mm, 200-300 gm, and six to seven years. Adult males

averaged 276 mm SV and 935 gm; adult females, 225 mm and 475 gm. The

largest male measured 360 mm SV and 1864 gm; largest female, 292 mm and

1135 gm. Adults grew between 2 and 17 mm SV/year.

Rock iguanas were primarily herbivorous at all ages, and fed

arboreally and terrestrially. Five partial septa partition the proximal

colon region; this modification presumably increases digestive efficiency.

Huge oxyurid nematode populations inhabited the colon, and their relation-

ship with the iguana may be mutualistic rather than parasitic. Abdominal

fat deposits were negatively correlated with gonadal activity.

Home range was correlated with body size and habitat productivity,

and averaged 980 m2 for females, 1260 m2 for subdominant males, and 1590
2
m2 for dominant males. Diurnal activity was bimodal during warmer

months; high midday temperatures resulted in reduced activity. Winter

activity was generally reduced and peaked at midday. Iguanas basked

following emergence; most of the remainder of the day was spent feed-

ing, interacting with other lizards, and shuttling in the sun-shade

mosaic for thermoregulatory purposes. Basking preceded the termi-

nation uf daily activity

Rock iguanas performed ritualized "signature" displays or head-

bobs. ?ostural adjustments were among the modifiers producing variation

in this display in different behavioral contexts. Displays were important

to territory declaration, male challenging, and sex recognition. Males

were territorial year-round in the field, but developed dominance

hierarchies in captivity. Dominant males displayed less than subor-

dinates. Male territorial defense probably evolved as a mechanism










guaranteeing access to 1) food resources, and 2) females for breed-

ing.

Sex ratio was 1:1 in all age classes. Survivorship was positively

correlated with body size. Juvenile densities reached 90.3/ha in

optimum habitat, adults exceeded 31.1/ha. Biomass estimates were 5.15

kg/ha for juveniles and 17.01 kg/ha for adults. Life table data

indicate replacement rate was near unity, and mean generation time

was 14.0 years. In its life history strategy, C. carinata is a

predominately K-selected species.

Cyclura are vulnerable to few native predators, but suffer

drastic population reductions with the introduction of feral mammals.

Virtually the entire iguana population of one study island (> 15,000

individuals) was extirpated by dogs and cats during the course of this

study. The status of Cyclura carinata in the Turks and Caicos Islands

was assessed and a management program congruent with the most critical

aspects of the life history of the rock iguana was recommended.















INTRODUCTION


Purpose


The genus Cyclura is one of the most poorly known lizard genera in

North America, despite being one of the most conspicuous members of the

West Indian Fauna. Although a sizeable literature exists regarding the

genus, most of the references are faunal lists or general works and

contain only anecdotal information; no thorough autecological study of

any of the species has been made.

Few New World lizards have experienced as intimate a relationship

with man, and suffered more from the interaction, than Cyclura. Major

populations have been extirpated within historic times. Probably no

presently existing population is entirely free from pressures induced

by man and his animals. It is increasingly clear that a thorough

knowledge of the habits and adaptations of our fauna is necessary if we

are to be able to insure their survival in the face of continuing and

increasing cohabitation with humans. It was for these reasons that

study was begun on a still relatively common species: Cyclura carinata,

the Turks Island iguana. From September, 1973, through June, 1976,

C. carinata was studied both in the field in the Turks and Caicos

Islands and in the laboratory.

The goals of the study were: 1) to obtain data on the behavior,

adaptations, life history, and community role of this species; 2) to

determine what factors limit population size; 3) to propose methods by

which the species might survive cohabitation with man, without threat










of extinction; and 4) to provide an indepth charter study for extrap-

olation to similar investigations of other less common and more

endangered species of Cyclura in the West Indies.


Systematic Relationships and Distribution

The genus Cyclura is most closely related to the three largest

herbivorous iguanins lizard genera inhabiting continental North and

Central America: Ctenosaura, Iguana, and Sauromalus. On the basis of

myology and osteology Cyclura is most similar to Ctenosaura and next

most similar to Iguana (Avery and Tanner, 1971). Endemic to the

Antilles and Bahamas, Cyclura apparently evolved from a pre-Ctenosaura

stock isolated in the islands. The genera Amblyrhynchus, Brachylophus,

Conolophus, Ctenosaura, Cyclura, Dipsosaurus, Enyaliosaurus, Iguana, and

Sauromalus comprise the subfamily Iguaninae (Avery and Tanner, 1971).

There are seven extant species comprising the genus Cyclura,

distributed from the northern Bahamas through the Greater Antilles

(Schwartz and Thomas, 1976). Pleistocene remains are known from

several islands within the present range (review in Carey, 1975).

Cyclura carinata is closely allied to C. rileyi (San Salvador,

Bahamas). The two species share a number of characters (lack of enlarged,

tubercular, median frontal shields; presence of dorsal crest, with

elongate spines, interrupted on shoulders and rump; maximum size less

than 1 meter, etc.) and are both distributed in the southern half of the

Bahaman archipelago.

The relationship of Cyclura ricordi (Hispaniola) to C. carinata

deserves additional study despite the larger size (commonly exceeding

one meter total length) of the former. The two species have similar










dorsal crests, pigmentation patterns, and are the only two species of

Cyclura without enlarged supracephalic scales.


Study Area

The Turks and Caicos Islands lie to the southeast of the Bahama

Islands between latitude 210 and 220 N and longitude 710 and 72031' W

(Figure 1). Although politically distinct from the Bahama Islands,

this British Crown Colony is geologically part of the Bahaman Archi-

pelago. The islands are situated approximately 150 km north of

Hispaniola and 890 km southeast of Miami, Florida. They consist of

two groups of islands separated by a 35.5 km wide, deep water (> 2200 m)

channel, the Turks Island Passage. The Turks Islands lie east of the

passage, the Caicos, to the west. The former consist of two inhabited

islands (Grand Turk and Salt Cay), six uninhabited cays and numerous

emergent rocks.

The Caicos Islands lie along the perimeter of the Caicos Bank, a

northwest-to-southeast-lying triangular shoal with a base and altitude

of approximately 125 and 75 km, respectively. Depths frequently exceed

180 m within 2 km of the reefs surrounding the Turks and Caicos banks.

Each of the banks is surrounded by depths of at least 1800 m. The

highest elevation in the islands barely exceeds 85 m (on Providenciales).

The present surface area of the islands, as calculated by the Turks

and Caicos Survey Department, is approximately 500 km, with only

27 km2 in the Turks Islands group. Recent evidence indicates that

shoaling sand is filling many of the cuts, linking previously separated

cays via sandy isthmuses (Noble and Klingel, 1932).


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Although these changes are usually not rapid, the effects of

tropical storms can be. When Hurricane Donna passed directly over the

Caicos Islands in 1960 the cut between Pine and Water Cay was blocked

by sand, connecting the islands. Shoaling since then has nearly

filled the cut. These changes are now and probably have been in the

past, very important to the dispersal of fauna and flora between islands

of the bank.

My studies of Cyclura carinata in the Turks and Caicos Islands

were predominately based in the West Caicos Cays. The major islands

comprising this group are, from north to south, Parrot, Dellis, Fort

George, Pine, Water, and Little Water Cay (see inset, Figure 2).

Studies reported here were confined to the latter four. These islands

are phenetically very similar. Each has its leeward sandy beaches,

windward rocky coasts and mangrove swamps, inland brackish water lakes,

northeast-to-southeast lying karst ridges paralleled by sandy dunes,

maximum elevations of eight meters, vegetation increasing in luxuriance

from west to east, and dense Cyclura populations.

Study was concentrated on Pine Cay, a privately owned island of

nearly 350 ha (Figure 2). The average elevation on Pine Cay is less

than three meters. Only three points on the island exceed six meters;

the highest point on the island barely exceeds eight meters. Extraor-

dinary in the Bahama Archipeligo, Pine Cay lies over an impermeable basin

preventing salt water intrusion. Maintained solely by rainfall, a

freshwater lens sometimes exceeding 15 m in thickness occupies this

banin. Average storage capacity has been estimated at over 510 million

liters. The water table is exposed in seven inland lakes. This

availability of fresh water is in part responsible for the presence

































Figure 2. Topographic map of Pine Cay, Caicos Islands, showing
locations of principal study sites: 1.) SW Blind, and 2.) Ridge
Area. Letters A through F indicate sectors of flush transect route
(dotted line). Other trails and roads are not illustrated. Dashed
line encloses limits of Hotel grounds. Unnumbered shaded areas
indicate lakes.


























PINE CAY


1M rEOr
LI~U-I










on Pine Cay of an extensive stand of Caribbean pine (Pinus caribaea)

found elsewhere in the Bahamas only on North Caicos, Grand Bahama,

Abaco, Andros, and New Providence (Rabb and Hayden, 1957). Vegetation

on Pine Cay varies from sparse on the most recent westerly sand beach

ridges to dense on the geologically older coral ridges to the east with

better developed soils (see Vegetation).

During the summer of 1973, construction began on a private resort

hotel, the Meridian Club, on Pine Cay. I was thus presented with an

opportunity to study the consequences of increased human interference

on theretofore relatively undisturbed iguana populations.


Zoogeographic Relationships

The Turks and Caicos fauna is part of a larger southern Bahaman

faunal group which includes the islands southeast of the Crooked Island

passage plus Rum Cay and Watling's Island farther north. At least 19

reptiles are endemic to the area, and although strongly divergent, most

have a Greater Antillean ancestry (Schwartz, 1968). This is despite

the fact that the Bahaman platform has had its closest geological

relationship with the North American tectonic plate since Triassic

times (Freeland and Dietz, 1971).

Among the amphibians, only Hyla reaches into the southern Bahamas

from the north and then only to the Mayaguana passage. None are

associated with Cyclura carinata. Over 115 species of birds have been

identified on the Turks and Caicos Islands (Buden, pers. comm.).

Differentiation of at least tuo of these has occurred within the

southern Bahanan faunal region: Columbina passerina and Calliphlox

evelynae (Bond, 1961). The avian species most important to the biology










of Cyclura will be discussed under sections concerning specific relation-

ships (see INTERSPECIFIC COACTIONS and FOOD AND FEEDING). Among the

depauperate mammalian fauna only the bat Monophyllus redmani has

apparently diverged within the southern Bahamas (Buden, 1975).


Materials and Methods

Preliminary evaluations of Cyclura populations in the Turks and

Caicos Islands were made by Walter Auffenberg between August 4 and 14,

1973- Those investigations revealed Pine Cay in the West Caicos Islands

to be the most feasible island for study for several reasons, including

the availability of water and adequate lodging, and the presence of an

extremely dense Cyclura population. Specific study sites on Pine Cay

were designated during my first visit in September, 1973.

Eleven trips to the Caicos have been made, with 163 days spent on

Pine Cay and nearby islands (September 15-29, December 8-22, 1973; March

2-16, June 1-July 20, August 29-September 10, November 26-December 6,

1974; April 1-14, July 29-August 16, November 4-11, 1975; and May 1 to 8,

June 8 to 15, 1976). Twelve additional days were spent observing and

assessing Cyclura populations on numerous eastern islands of the Caicos

Bank. Field notes from the Caicos islands were made available by Walter

Auffenberg (48 study days from September, 1973 through 1975) and David

Auth (112 days from June, 1974 through February, 1976). Copies of all

of our field notes are filed in the Herpetological Library of the Florida

State tlMseum.

A site of approximately 0.9 ha in the southwestern corner of Pine

Cay was chosen as my major study area to be used mainly for behavioral

observations with as little interference and manipulation as possible on










my part (Figure 3). The area was initially chosen due to the abundance

of lizard spoor and manure on open areas, and the generally good visi-

bility below the canopy.

An abundance of signs typically reflects lizard density in the

immediate area. Since Cyclura carinata on Pine Cay were extremely shy,

it was necessary to construct a blind in this southwestern study site.

Lizards generally ignored the blind after it was in place for only one

day. A total of 47 days (287 hours of actual observation) was spent in

this bline during the study period. In order to accurately quantify

observed lizard movements, yellow marker flags, spaced six meters apart,

were placed in a measured grid system around the blind. Each marker was

assigned a letter N (north of the blind) or S (south), and a number

(related to the distance from the blind). Thus a lizard at "N-5 West

three meters" was located three meters west of marker number "N-5". This

greatly increased the speed and accuracy of data recording, and allowed me

to tabulate precise lizard movements. Over the course of field work, this

entire study area was very thoroughly and accurately mapped. Surveyors and

topographic maps, prepared under the direction of Liam Maguire of the

Meridian Club and based on numbered cement lot markers on Pine Cay, and

aerial photos (personally taken) made possible precise mapping of lizard

and other landmark locations.

Field notes were recorded on a cassette tape recorder each day and

transcribed in the field notebook at night. A Minolta SRT 101 35 mm camera,

SonyAV 3400 portable video camera and recorder, and CAFST/602 Super 8 movie

camera were all employed to record lizard behavior. In excess of 1400 slides,

110 minutes of videc and 50 feet of movie film were taken. The utmost care

and patience was always taken at the southwestern blind to minimize inter-

































Figure 3. SW Blind Study Area





13






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ference with the natural system. Early in the study the resident popu-

lation was marked without handling by means of a "Paint Rifle", a large

plastic syringe firmly mounted on the end of a 1 m, 2 cm diameter, dowel.

Maximum range exceeded ten m, with accuracy possible to six to seven m.

Lizards were not at all bothered by this technique. By shooting various

colors of paint on various parts of the body, recognition of individuals

was possible. Index cards with outline drawings of the right and left

sides of a lizard were used to record marking and color formation, as

well as sex and natural external morphological data for each lizard.

The cards were modified as parts of the paint pattern were shed and/or

the lizards were remarked. Even after three month absences, remnants of

paint patterns, in conjunction with activity range and behavioral

information, could be used to re-establish the identity of individual

lizards.

As the study progressed, lizards were occasionally noosed from the

blind for accurate measurement. In order to attract lizards to the blind

for this purpose, as well as to induce lizard interaction, numerous

substances were experimented with as "baits". Among the items tested

were local fruits and flowers, soda and Ritz crackers, peanut butter,

vanilla extract, crab parts, other vertebrate carrion, and sardines.

The latter was the only substance that proved effective as a bait, and

its effect was striking; adult males would occasionally cross the

territories of at least three other territorial males to obtain the

sardines. This bait was, however, less effective during the colder

parts of the year and also when high winds rapidly dissipated the fishy

odor. Foreign (to the study site) lizards, restrained in hardware










cloth cages or on tethers, were sometimes introduced into the activity

ranges of established lizards and the resulting behavioral interactions

recorded.

Lizards on islands with even minimal human traffic were difficult

to capture by noosing except from blinds, so this technique was not

frequently used on Pine Cay, except at the southwestern blind study

site (hereafter referred to as the SW Blind). The technique was,

however, fairly successful on islands rarely visited by humans.

Juvenile lizards and occasional adults could be secured by chasing

them under rocks or into hollow sticks and logs, from where they could

be removed by hand. Noose snare traps and funnel traps at burrow

mouths in areas of great activity were each experimented with, but

met with only minimal success. Lizards were sometimes obtained by

removing them from their burrows. Nests discovered in this process

were either removed to the laboratory or marked for further observations.

Numerous freshly killed or mortally wounded individuals were also secured

from the mouths of local dogs and cats. In addition, the dried remains

of many mammal-killed Cyclura were collected. An attempt was made to

collect a sample of at least a few lizards during each season of the

year to be used for dissection. Besides those lizards killed by dogs

and cats, the bulk of this sample included lizards removed from the area

on Pine Cay destined for occupation by a hotel and its adjoining beach

cottages. Since most of these lizards would have been killed by bull-

dozer activity, this seemed the best source of material for dissection.

Specimens for dissection were weighed, measured, and preserved in

formalin in the field. Transferred to isopropyl alcohol in the laboratory,

preserved specimens were autopsied for reproductive condition, gut










content, fat bodies, and presence of parasites. Ovaries, testes, and

fat bodies were excised, blotted, and weighed to the nearest 0.01 gm.

In females, all yolked ovarian follicles, oviducal eggs, and corpora

lutea were measured to 0.1 mm with dial calipers. Testes volume was

determined by water displacement.

In order to collect data on growth, lizards located in the area

immediately adjacent to the site chosen for construction of the hotel

were marked and released on the first visit to the study island. On

each of four succeeding visits within a year, no recaptures were made

despite a continued marking program all along the dunes parallel to the

northwest coast. The disappearance rate in this habitat was obvious

on my first return to the island (December, 1973) when not a single

iguana was seen in my original mark-recapture area. A second site was

sought, one less disturbed and more densely populated. In July, 1974,

another mark and recapture program was initiated on an area of approxi-

mately 1.85 ha on the north end of nearby Little Water Cay (Figure 4).

Habitat and vegetation there are virtually identical to the areas of

Open Scrub on Pine Cay (see HABITAT). Growth data were also collected

on numerous juveniles maintained in laboratory on lettuce, cat food,

and bean sprouts.

Body length (snout to vent), tail length and condition, body

weight (measured to the nearest five gm on a Chatillon 3 kg spring

balance), sex (when possible), and any other obvious external morpho-

logical characters (especially in juveniles) were recorded for all

lizards during the mark and recapture program. Maximum height (in mm)

and number of annuli on dorsal spines of the neck, back, and proximal

tail regions were also recorded for each adult. Each lizard was then




















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marked with a unique combination of at most two clipped digits, and

released as soon as possible following capture (always within the hour).

At the SW Blind "belts" of various colors modified from cat collars

were secured around several lizards "waists" for later recognition.

In addition to lizard movements observed at the SW Blind, it was

sometimes possible in sparsely vegetated dune sand areas to map a single

lizard's activity range for a single day by his spoor. Since rain and

wind quickly obliterate the tracks, this method is useful only if

mapping is done late in the afternoon (following lizard submergence)

on days lacking high winds or precipitation. A 15 m length of kite

string was several times secured around a captured lizard's abdomen

just anterior to his hind limbs. On release he would drag the string

through the bush and a small portion of his movements could later be

plotted. The success of this method varied, since the string occasion-

ally became entangled in brush and was broken. A three m length was

similarly employed with success to locate captured lizard's home burrows

at the SW Blind. Following lizard submergence, known burrows were

checked for string trailing into them.

Lizards were also tracked using radio telemetry. This technique

was used effectively in lizard displacement and homing experiments as

well as for recording daily movements. All telemetry equipment was

purchased from Mini-Mitter Co., Inc., Indianapolis, Indiana. Transmitters

used were Model L Mini-mitters operating at just over 27 MhZ. A 3-channel

Lafayette HA 420 walkie-talkie fitted with a Mini-Mitter Beat Frequency

Oscillator served as a receiver. A Mini-Mitter Model AF Directional

Antenna w'as employed early in the study; however, technical problems

precluded its use for most of the study. Triangulation by signal










strength received from a whip antenna along right angle transects

proved much more effective, especially in areas of dense vegetation.

The signal with this equipment varied from 100 m in sparsely vegetated

dune areas to just over 50 m in thickly vegetated, rocky areas with

greater relief. The range was entirely sufficient for successful use

with this species.

Transmitters were secured to the previously described cat collar

identification belts with electricians tape and strapped to the lizard's

waist. A short length of twine was tied to the transmitter package atop

the belt. Transmitter retrieval could then be accomplished by simply

pulling the package from the lizard (leaving the belt in place for

identification) as he lay in his burrow at night or early morning.

In this way, a second disturbance of the monitored lizards was eliminated.

The short trailing string did not seem to bother the lizards or hamper

their movements in any way.

Measures of lizard activity were made in basically three ways:

1) direct observation; 2) clocking mechanisms at burrow entrances, and

3) flush transects. To record lizard emergence and submergence times,

an alarm clock was remodeled as a single-event recorder in a technique

similar to that of Arltan (1936). A hole was drilled through the outer

case of each of several inexpensive spring wind clocks directly above

the timing wheel. The gravity operated trigger mechanism consisted of

a small square of cardboard over which an elongate paper clip loop was

suspended. A fine nylon thread attached to the cardboard square was

stretched across the entrance of a lizard burrow. Disturbance of the

thread removed the cardboard allowing the wire loop to drop through

the timing wheel, stopping the clock.










A flush transect method similar to the 'King strip census' (see

Giles, 1971, for discussion) was also utilized for activity patterns as

well as density estimates. The technique consisted of traversing a

permanent census trail at different times throughout the day during each

visit to the study island (Figure 2). Distance along the transect route

where each lizard was flushed and distance from trail to lizard (before

being flushed) were recorded. A total of 103 transects was run during

the course of the study. Data from the flush transects, coupled with

direct data at the SW Blind study site provided the major basis for

analysis of activity patterns and estimates of lizard density. In order

to test and insure the accuracy of this transect method, the transect

route passed through the SW Blind site, from which the most reliable den-

sity data was presumably available. The success of flush transects on

Pine Cay was the result of the character of the island itself as well

as that of the lizard. Cyclura on the study island are very wary and

typically run when a human approaches. Although many lizards were

seen during transects, the location of most was possible only after they

bolted off over noisy leaf litter. This technique could therefore be

successful only in areas where the vegetation was dense enough to prevent

the lizard from seeing the observer until he (the observer) was within

audible range of the noise of his flushing. Such was the case along the

transect route I utilized.

Lizard burrow structure was investigated by digging up several

burrows. Inactive burrows were usually chosen for excavation in order

to minimize interference with lizard populations. However, several

active adult burrows were unearthed in order to obtain the inhabitant










in an attempt to correlate burrow structure with sex and size. Lizards

so obtained were either displaced for homing experiments, brought to the

laboratory for behavioral observation, preserved for dissection, or

released into nearby inactive burrows after marking. The structure,

including length, direction, depth and substrate for all parts of each

excavated burrow was recorded. Eggs unearthed in nature as well as

captive clutches were removed to the laboratory in Gainesville for

incubation in moist sand under constant conditions. In an attempt to

study turnover rates in burrow utilization, all burrows in a randomly

chosen circular area (radius 26 m, area 0.22 ha) along the limestone

ridges of the leeward side of southwestern Pine Cay were surveyed on

six consecutive visits beginning in December, 1973. This site was

designated the Ridge Area (Figure 2).

Before analysis of diet in this herbivorous lizard was possible,

it was necessary to collect and identify the majority of the plant species

on Pine Cay. Bob Anderson, graduate student in Botany, University of

Florida, accompanied and assisted me in making preliminary plant

collections and identifications, and vegetation transects, on my first

visit to Pine Cay, in September, 1973. Thereafter, plant samples were

recollected seasonally by myself and Walter Auffenberg, so that as many

vegetative forms (especially reproductive parts) as possible of each

species were available to us for identification. Botanist Don Correll

of Fairchild Tropical Gardens, Miami, Florida, made further plant

collections and identifications during a visit to the Caicos in August,

1974. From these various collections, a reference catalog of seeds,

fruits and leaves was built up for use in identification of lizard

food items.









To supplement stomach content analysis from preserved specimens,

311 scats were collected from the SW Blind and Ridge areas for use in

food studies. Walter Auffenberg collected an additional 308 samples

from other areas on Pine Cay. Old scats (those bleached and/or broken

apart) were not collected on Pine Cay in order to eliminate the possi-

bility of sampling a time period other than the current one. However,

all manure encountered on other of the Caicos islands were collected

for analysis. In all, over 670 scats were available for study. Seeds,

elements of arthropod exoskeletons, and most leaves pass through the

lizard's digestive system with almost no alteration in shape, making

food item identification possible from the manure. Records were also

made of species and parts of plants directly observed to be eaten by

Cyclura. Indirect information on diet came from iguana tooth marks

on partially cropped plant parts.

Environmental temperatures were taken with an Atkins Model 3FO

recorder with remote sensing probes. Precipitation was collected in a

standard 5" capacity rain gauge, but was monitored only when an

investigator (David Auth or myself) was on Pine Cay. Climatic infor-

mation collected continuously from 1900 to 1968 at Grand Turk Auxiliary

Airfield, Grand Turk (21026'N, 718'W; elevation 4 meters) and provided

by the National Climatic Center, Asheville, North Carolina, has been

used to supplement data recorded on Pine Cay.

An enclosure approximately 3 x 8 m with walls 1.25 m high, was

constructed in my yard in Gainesville, Florida for captive behavioral

observations. An observation blind was erected adjacent to the pen.

Seven burrows of buried hollow concrete blocks were available in the


~










pen. The substrate was well vegetated with lawn grasses and small weeds.

Eight clumps of Opuntia sp. were added, and the pen was seeded semi-

monthly with lentil bean and assorted flower seeds. An ad libitum food

supply of lettuce, bananas, commercial cat and dog food, sardines, tomatoes,

and Opuntia blossoms (when available) was provided. A full ten liter water

pan was maintained. Observations were made during mornings and were

terminated during the usual midday reduction in lizard activity. Captive

lizards were brought into the laboratory during the winter. They were kept

in pens similar to those outdoors except in their smaller size and use of

250 Watt infrared lights as heat sources.

Several terms used herein require clarification. The "Study Islands"

include Fort George, Pine, Water, and Little Water Cays; the "Study

Island" refers to only Pine Cay. The principal study sites on Pine

Cay are designated as the SW Blind, and Ridge Area (Figure 2). Lizard

body length or snout-vent length is abbreviated as SV; tail length as TL.

All allusions to lizards, rock iguanas, or iguanas, refer to Cyclura

carinata unless otherwise qualified by scientific name. All material

collected incidental to this study including other vertebrate and

invertebrate specimens, has been placed in the collections of the

Florida State Museum, University of Florida. Statistical methods are

those of Steele and Torrie (1960) unless stated otherwise. Means are

ordinarily given with + one standard deviation. Definitions of

behavioral terms appear in text.














MORPHOLOGY


Cyclura carinata Harlan was described in 1825 from "Turk's Island".

The location of Harlan's holotype is unknown. The species can be

diagnosed as follows: Nasals broadly in contact with the rostral.

Frontal, fronto-parietal; and occipital regions covered by small

irregular, strongly keeled scales. Circumorbital scales smaller than

other supracephalic scales. Two to 4 enlarged, vertically arranged

canthal scalses on each side. Dorsal crest broadly interrupted on the

shoulders and rump; nuchal section of the crest with 16 to 20 spines

(up to 2 cm) which are longer than the 45 to 75 spines on the back.

Dorsal crest spines exceed 5 mm in height only in males. Femoral pores

average 21 on each leg (range 18-25). Verticil rows on the tail strongly

keeled, with four vertical scale rows between fifth and sixth rows.

Mid-dorsal tail scales enlarged and sharply keeled. Males less than

80 cm total length, females less than 65 cm.

Two subspecies are recognized. The nominate subspecies can be

distinguished by having the nasals separated by a large wedge-shaped

scale; spinose, hexagonal scales on the outer tibial region, 3 or 4

of which equal the diameter of the tympanum; and fewere than 60 spines

in the dorsal crest. Cyclura c. bartschi described from Booby Cay,

east of Mayaguana Island, Bahamas Island (Cochran, 1931) is character-

ized by nasal scales usually in contact; 4 or more tibial scales equal

to tympanic diameter, and usually more than 60 spines in the dorsal

crest.










The following morphological descriptions are based only on specimens

and data obtained in Caicos Islands.

Dentition. The teeth of Cyclura carinata are heterodont. They are

unicuspid at the symphysis and on the premaxillary; the remainder of

the anterior teeth are strongly tricuspid. Median and posterior teeth

are strongly compressed laterally and flared anterlo-posteriorly, with

a multicuspid cutting edge; the large median cusp is flanked by two

or three smaller anterior and one or two posterior cusps. The tooth

formula follows: 0-10 pterygoid; 0 palantine; 4-10 premaxillary; 17-23

maxillary; and 19-28 dentary. The dentition of C. carinata is similar

to the other iguanines (all herbivorous) in both tooth counts (Table 1)

and the presence of increasing cuspidation from anterior to posterior

along the dentary and maxillary (see Avery and Tanner, 1971, for

comparisons). The nearly contiguous, laterally compressed, multi-

cusped, pleurodont teeth forming a continuous shearing surface are well-

adapted for leaf chopping and shearing (Hotton, 1955; Ray, 1965;

Montanucci, 1968). Tooth counts (actually tooth positions) in Cyclura

carinata increase ontogenetically (Figure 5) like those in Ctenosaura,

Iguana and Anolis (Ray, 1965; Montanucci, 1968). Both maxillary and

dentary counts were positively correlated with skull length (r = 0.905

and r = 0.843, respectively).

Skeleton. The basisphenoid is wider than long and slightly to moderately

constricted behind the pterygoid processes; length/width ratio: 0.65-0.72.

Five or more foramina are present on the superficial surface of the rostral

part of the premaxilla. The parietal foramen is small and pierced in the

frontal or the fronto-parietal suture. The parietal is not produced


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posteriorly. Angular and splenial elements are present. The splenial

is long and narrow. The dorso-ventral borders of Meckel's groove are

fused anterior to the splenial. The antero-ventral alveolar foramen is

partially enclosed by the border of the splenial; the coronoid possesses

a large process overlapping the dentary (Figure 6). 24 presacral

vertebrate are usually present. The postero-ventral angular process is

pointed and elongate, and directed antero-medially. Each presacral

vertebra is provided with zygosphenes and zygantra in addition to

zygopophyses. At least some autotomic caudal vertebrae have two pairs

of transverse processes, the fracture plane passing between them.

Scapular and secondary coracoid fenestrae are well-developed; clavicles

are simple or with posterior hook-like processes; the interclavicle is

T-shaped or arrow shaped; the sternal fontanelle is small or absent;

and four sternal and two xiphisternal ribs are present (Figure 6).

The hyoid apparatus of Cyclura carinata was studied by Avery

and Tanner (1971) and my observations (Figure 6) do not differ from

theirs.

Hemipenis. The hemipenial structure in the genus Cyclura has not

previously been illustrated. Since the only description available for

the hemipenis in this genus is a brief one by Cope (1896), the organ

in Cyclura carinata is here described. The hemipenis is single-lobed,

subcylindrical to clavate. The sulcus spernaticus is a broad open

groove along the posterior surface of the hemipenis. Calyces cover

the distal half of the hemipenis, whereas the proximal half is covered

with irregular creases. Spines or spinose structures are lacking.

Based on hemipenial structure, Cyclura is most similar to the iguanine

genera Iguana and Amblyrhynchus (Avery and Tanner, 1971).























A


C





Figure 6. Skeletal elements of Cyclura carinata: A) Sternum
(ventral view); UF 14354, Middleton Cay. B) Hyoid apparatus
(ventral view); UF 14354. C) Mandible (medial view; tooth
crown structure not illustrated); UF 32678, Middleton Cay.









Lepidosis. Lizards in the genus Cyclura are the only iguanids possess-

ing corneous subdigital combs on digits 2 and 3 (#4 = longest) of the

hind limbs. Subdigital lamellae are multicarinate, not flattened, and

lack a mat of hair-like processes.

Numerous other epidermal scale characteristics of Cyclura carinata

were presented above; additional descriptive data are not here presented

in anticipation of publication of a systematic analysis of the genus

by Schwartz and Carey (in press). As previously stated, the spines

of the mid-dorsal crest exhibit considerable sexual dimorphism in

size. In females, neck spines never exceed 5 mm in height; maximum

recorded back spine height for females was 3 mm. Dorsal spines on the

neck in males begin development (elongation) coincident with the onset

of sexual maturity. Thereafter each time the skin is shed the spine

increases in length and an annular impression is formed around its base.

After 2 sometimess) sloughs of the skin, the back spines begin develop-

ment in exactly the same pattern as those of the neck. Back spines

are therefore shorter and possess two fewer annuli than neck spines on

most individuals. The relationship of the spines to sexual recognition

and their annuli to growth and age are discussed later (see GROWTH).

In old lizards the back spines approach or even exceed the neck spines

in height, and the annuli become inconspicuous as the spines become

smooth due to wear. The middorsal spines on the anterior portion of

the tail in male iguanas also elongate with age albeit very slowly.

A maximum height of 18 mm is attained in extremely old individuals.

Color. Rock iguanas exhibit great individual and population color

variability. Patterns tend to be darker (gray, brown, or green,










on population) immediately following emergence and preceding sub-

mergence each day. The midday coloration is typically light gray to

bleached green (again related to population). This changing albedo

is presumably an adaptation to increase absorptive radiation in sub-

optimal ambient temperature regimes (Cowles and Bogert, 1944). The

change in color is most rapid during the morning basking period and

has been timed at less than one hour. The relationships of changing

albedo and skin reflectivity to thermoregulation are under study

(Auth, in preparation). Seasonal color changes, related to hormonal

levels, have been observed in numerous iguanid lizards (Carpenter, 1967;

Ferguson, 1976) however, no such changes were evident in the studied

population.

Inter-population color differences on the Caicos bank are very

pronounced. Lizards from the eastern populations (Middleton and Long

Cays) are very drab gray, dorsally and ventrally, with only slight

changes in darkness of the gray. Lizards from Fort George and Pine

Cays vary from a brownish to greenish-gray following emergence, to a

nearly white-gray at midday. The venter is gray to blue-gray. A very

abrupt pigmentation change occurs between Pine Cay and Water Cay to

the south. Lizards from both Water Cay and Little Water Cay are the

most brilliantly colored of Caicos populations. Basically a dark gray-

green on emergence, during basking these lizards become a pale yellow-

green. The typically lighter venter in these lizards is blue-gray

flushed with yellow. The yellow coloration extends over the tail and

on the ventral surfaces of the limbs and digits. Pine and Water Cays

have apparently been separated throughout historic time by a deep water










channel, allowing the maintenance of very different color morphs.

However, the channel was blocked with sand and Pine and Water Cays were

linked by a sandy isthmus as a result of tropical hurricane Donna in

1960. Iguanas have not yet breached the open sand barrier of the

isthmus, but will undoubtedly do so as primary succession provides

the necessary shade and food plants. The effects of genetic inter-

change on the integrity of the two color morphs will be interesting.

Cyclura carinata also exhibits a variable pattern of narrow

vertical stripes on the dorsal lateral body surface. The stripes are

most obvious near the anterior mid-dorsal line and become increasingly

less apparent laterally and posteriorly. The stripes typically number

9 or 10, and are areas where the pigmentation is simply lighter than

adjacent regions. The pattern is most obvious in hatchlings and

juveniles, and typically very obscure in adults.

Anatomy. Morphology of the thyroid gland in Cyclura carinata is

discussed by Lynn et al. (1966). Digestive tract anatomy is discussed

under FOODS AND FEEDING.


~














HABITAT


Climate


The Turks and Caicos Islands experience a typical tropical maritime

climate. East-southeasterly tradewinds predominate, averaging 22.5 km

per hour throughout the year, and annual air temperature- fluctuationsare

not great (Figure 7). Recorded annual air temperature extremes between

1960 and 1968 on Grand Turk (110 km to the east of the study island) were

15.6C and 36.OC. However, microclimatic temperatures show much greater

fluctuations both daily and seasonally. Temperatures on light coral

sand substrates ranged from 12.5C to 60.OC on the study island; those

on darker soils were considerably higher. Substrate temperature

differentials between exposed and shaded areas were greatest during mid-

day in July through August with a maximum recorded difference of 25C

(31-56C). Twenty degree divergences are typical of summer days without

midday precipitation. The maximum recorded winter (November-December)

shaded-exposed substrate differential was 18.5C.

To provide a general picture of the diurnal thermal environment,

microclimatic temperature data from optimum days (unaffected by overcast

or rainy conditions) on the study site were averaged by half hour for two

periods, representing the longest and shortest days of the year (Figure

8). Data from six days in late June, 1974, and six in December, 1973,

were used. These differences in summer and winter temperatures are in

part due to an annual fluctuation in day length (photoperiod) of nearly


~
































Figure 7. Average monthly temperature regime in Turks and Caicos
Islands. Substrate temperatures were recorded at SW Blind, Pine
Cay during study period; remaining temperatures collected between
1900 and 1968 at Grand Turk Airfield, Grand Turk.




























50-,


IN
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Figure 8. Average diurnal microclimatic temperatures for June and
December at SW Blind study site. Data averaged by half hour for
six storm-free days in June, and four in December. Arrows indicate
sunrise and sunset.






39



















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three hours (Figure 9). A more detailed analysis of the thermal environ-

ment and its relation to the biology of Cyclura carinata on Water Cay,

Caicos Islands, is found in Auth (in preparation).

Since it was possible for me to monitor rainfall only while on the

study island, data collected between 1900 and 1968 at the Grand Turk

Auxiliary Airfield (Latitude 21026'N, longitude 71008'W; elevation four

meters) are presented here, unless otherwise indicated. A well-defined

dry season exists from January through May with monthly rainfall averag-

ing only 13.5 mm (Figure 10). The wet season usually begins and ends

rather abruptly in June and January, respectively, and rainfall averages

62.8 mm monthly. In addition to amount of rainfall, the percentage of

days per month experiencing some rainfall also increases substantially

during the wet season (Table 2). Average annual rainfall on Grand Turk

is 597 mm. However, based on 458 mm recorded on Pine Cay in 194 days

over three years, the annual estimate is approximately 862 mm, somewhat

higher than on Grand Turk. Comparison of the vegetation, soil moisture,

and general weather conditions across the bank on several occasions, in

addition to information supplied by locals indicate that rainfall is

greater on the more western islands of the bank, but probably does not

exceed 760 mm annually.

Changes in rainfall, temperature, and photoperiod are the major

aspects of climatic seasonality. The effects of each of these are

reflected in lizard activity. Days are often cool enough to curtail

lizard activity in the winter, but almost never so in summer. The

climate in the western cays of the Caicos Islands is one of a warm dry

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which grades into an even wetter, but still warm autumn (September to

December), and is followed by cool, relatively dry winter (January to

March). Abrupt changes in temperature and precipitation characterize

the transition between the wet and dry seasons.


Soil

Reflecting their reef origin, the Turks and Caicos Islands are

characterized by honeycomb limestone formations usually covered with

coral sand. The rocks are typically exposed along the windward shores,

with broad sandy beaches along the leeward. Inland accumulations of

humus provide a rich nutrient source and support more luxuriant

vegetation (see Vegetation).

Iguanas frequent rocky and sandy areas as well as the more elevated

humus areas, but generally avoid the lower areas with thicker soils due

to the proximity of the water table to the surface and their inability

to dig through the root mass.


Vegetation

The spatial relationships of the principal vegetation types on

Pine Cay are illustrated in Figure 11 and listed in Tables 3 and 4. The

vegetation on Pine Cay corresponds to the "Evergreen Bushland" of

Beard (1949), and is physiognomically very similar to that found on

Anegada in the British Virgin Islands by D'Arcy (1975). The same genera

(if not species) are represented in similar habitats on both islands.

Although D'Arcy (1975) divided the flora of Anegada into only four

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plains, and vegetation near man), it seem justified on Pine Cay to

distinguish additional plant communities within at least two of his

provinces. A more thorough discussion of the components of the vegetation

types on Pine Cay and their relationships appearsin Auffenberg (in

preparation).

Cyclura carinata inhabits all of Pine Cay's plant commu:' t;s except

the Marsh and portions of the Mixed Woodland vegetation types. These

are areas where the proximity of the water table to the ground surface

precludes the possibility of burrow construction and vegetation is too

dense for movement. Cyclura reaches its maximum adult abundance on

Pine Cay in areas of Rocky Coppice. Young lizards are more commonly

observed in areas of Open and Dense Scrub.


Burrows

Unless natural shelters in the form of abandoned land crab

(Cardisoma guanhumi) burrows, or honeycomb limestone or coral formations

are available, Cyclura carinata digs its own burrows. Since natural

retreats are not abundant on the study islands, most lizards dig their

burrows. Large mounds of vegetation, dirt, and rocks piled up by

bulldozers while clearing roads are often used for retreats by lizards

on Pine Cay. These sites also offer excellent elevated basking sites.

Adult male iguanas exhibit great burrow tenacity. This is reflected

in the greater average length, depth, and complexity of burrows dug by

males versus those dug by females (Table 5). Sexual differences in

burrow depth are also due, in part, to the need for shallow incubating

chambers for successful nesting in females; burrow length differences








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are also related to sexual dimorphism in size. Though adults of both

sexes commonly use the same burrow, strongly territorial adult males

never share them, unless used as a retreat after having been frightened.

Although territorial adult male lizards near the SW Blind maintained

a single retreat, they were nevertheless aware of all burrows (and

other potential retreats) both within their own territories and well

into those of adjacent males.

Even subadult lizards showed familiarity with burrows far outside

their normal activity ranges. On September 20, 1973, adjacent to the

Ridge Area on Pine Cay, a 178 mm SV lizard was removed from its burrow.

Following marking, it was released at the site of its burrow. It ran

directly and non-stop 16.1 m, where it entered another active burrow.

The second burrow was found to contain the marked lizard, in addition to

its resident male (SV 229 mm). When released after marking, this resident

immediately ran over the ridge and directly to the burrow first excavated.

The lizard first marked sought refuge in dense vegetation when released.

Both lizards were clearly aware of the exact location of the other's

burrow.

Blocking of a territorial male's primary burrow causes him to shift

his retreat. Removal of the obstacle, after one to three days, is

followed by his return to the primary burrow. The effect of permanent

destruction of the primary burrow was not determined. The short term

blockage seemed to cause no change in activity range location, but a

shift is suspected if the burrow is destroyed.

Juveniles and subadults frequently shift burrows. One subadult

non-territorial male, carrying a transmitter, in the SW Blind area,










utilized three different burrows on three consecutive nights. However,

in some areas the unavailability of auxiliary retreats necessitates the

continual use of a single site. A hatchling took up residence in a small

hollow tree limb in a brush pile on September I, 1974, within only a few

days of emergence. It still occupied the site in April, 1975, when last

observed. Since it was never again seen on the study site, it is

presumed it was killed.

The following patterns in burrow usage were observed in the Ridge

Area. Large burrows active at the beginning of the study remained

active throughout the study period. There was, however, considerable

small burrow turnover, probably due to 1) predation on juveniles; 2)

lack of burrow tenacity in juveniles; and, 3) periodic excavation of

burrows by terrestrial crabs. Since the burrow is central to all

activity in Cyclura carinata, its importance cannot be overemphasized.

Not surprisingly, burrow construction in all species of Cyclura

seems to be related to the substrate conditions. In areas where sandy

dune situations predominate, as on the typically small, low islands of

the Bahaman archipelago, constructed burrows are used. However, on

islands dominated by cavernicolous limestone and coral exposures the

possibility of burrow excavation by iguanas may be precluded. Natural

retreats are then employed (see Retreats under ACTIVITY AND MOVEMENTS).

The presence of at least some friable soil for nest construction

appears to be a very important factor ultimately limiting distribution

and numbers of Cyclura populations. In the species of Cyclura for which

the nest site has been described (Foble, 1923; Wiewandt, in preparation),

a nest burrow was excavated in well-insolated soil areas, sometimes










several km from the female's normal activity range (see Discussion

under REPRODUCTION). In addition to protection, burrows could serve

a thermoregulatory function, however lizards do not use them as heat

sinks, even under extreme conditions.

Adult Cyclura typically maintain their burrows by removing sand,

leaves, and other debris during the middle of the day when general lizard

activity is reduced due to high environmental temperatures. However,

this is not a daily routine; a period of several days generally

separates burrow cleaning activities. In removing debris, the lizard

enters the burrow head first and kicks material backward as it moves

further inside. Exiting the burrow head first, it turns and repeats

the procedure several times.

The complete excavation of a burrow was never observed, so t'- time

required is unknown. However, a young adult male completely excavated a

new burrow near the SW Blind during my absence between July 20 and

September 1, 1974.

Neonate lizards usually utilize natural cavities or spaces cleared

beneath rocks,roots, logs, etc., for retreats. In open sandy areas,

they will excavate their own burrows. These burrows are usually shallow

(< 15 cm deep) and short (< 50 cm), with diameters between 2.5 and 3 cm.

Some have short side branches but these may be added by crabs.

Since many young lizards frequent more than one burrow and many

small burrows are actively maintained by crabs, small burrows are not

useful in estimating lizard density. Data on locations of large active

burrows can, however, provide fairly accurate estimates of adult lizard

density (see DENSITY AND DEMOGRAPHY).









Burrow dimensions and complexity are quite variable (Figure 12),

dependent in part on the surface and subsurface soil texture. The

longest burrow excavated was in dune sand on Pine Cay, and measured

6.4 m. It was occupied by both a female and a male when opened. One

of the biggest burrows encountered was an active one which I could not

completely excavate. The burrow was in an area of deep dune sand nearly

devoid of vegetation. The 16 cm diameter of the burrow suggested that

it had been dug by a male. After 5.0 m of horizontal excavation, the

burrow was 1.5 m below the sand surface. It continued downward with the

same slope at least one m farther. Digging was suspended due to constant

collapsing of the excavation pit.

Burrow orientation on Pine and Water Cay (Figure 13), appears to

be related more to micro-topographic features than to intentional

directional construction. More burrows generally open to the northwest

and southeast on these two islands, because these retreats lie perpen-

dicular to the generally northeast-to-southwest lying ridges (Figures

2 and 12). Cyclura prefers digging under the limestone exposures in

the sides of these ridges to digging in open flat sandy areas. In the

latter areas, burrows are typically excavated into the sides of small

hummocks formed by the accumulation of blown sand around the bases of

clumps of vegetation. An obvious advantage in avoiding flat areas of

open sand for burrow construction is the reduction of the possibility

of entombment by burrow collapse.

As in the burrows of the Florida gopher, Gopherus polyphemus

(Young and GoFF, 1939), there are in nearly every Cyclura burrow,

numerous arthropod inquilines, many apparently obligatory. The most































Figure 12. Variation in burrow morphology and orientation in adult
Cyclura carinata. Soil depth (in cm) to top of burrow is indicated;
changes in depth are uniform between measurements. Letters adjacent
to burrow entrance (solid circles) indicate sex of inhabitant.
Asterisks mark burrows used for nesting in previous yeers.


I



















90


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13 15 15


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_ __1~---1~-~1~---L^---^111~--1





























































Figure 13. Orientation of burrow entrances in Cyclura carinata,
recorded as compass direction into burrow.





67



common and seemingly most obligatory were camel crickets (Ceuthophilus?).

Also found were solpugids (genus Ammotrechella), scorpionids, amblypygids

(Tarantula marginepennis), nymphal cicadas (Ollanta caicosensis), and

numerous unidentified spiders.














REPRODUCTION


Male Sexual Cycle

The male testicular cycle closely parallels the female reproductive

cycle. Since testes weight has been shown to be an accurate indicator

of testicular activity in lizards (Hahn, 1964; Marshall and Hook, 1960;

Ballinger, 1973), no histological analysis was made. Testes reach

maximum sizes in April and May, declining rapidly in June and July to

complete regression in early fall (Table 6). Testicular size maxima are

coincident with breeding in Cyclura carinata. A similar cycle (early

spring maximums and late summer minimums) is typical of at least the

Iguanid lizards.

Sexual maturity in male C. carinata was determined by testicular

enlargement between January and June, or actual observation of attempted

or successful matings in May. The smallest male with enlarged testes

measured 216 mm SV (weight approximately 440 grams). The largest males

without testicular enlargement were 222 mm SV (435 gm live weight) and

210 mm SV (365 gm). A 219 mm SV captive male which attempted copula-

tions on numerous occasions during May, 1975, was the smallest male

observed to exhibit courtship behavior. These data indicate sexual

maturity in males is reached at approximately 220 mm SV and a body

weight of 375 to 475 gm. Growth data indicate this requires about seven

years (see GROWTH). Adult males averaged 276.3 mm SV (191-360) and

935.1 gm body weight (256-1864).


68
















Table 6. Seasonal variation in proportional testes weight
(testes weight in gm x 10-5/sV in mm) in male Cyclura
carinata over 216 mm SV.



Sample
Date N 7 S.D. Range

March 6 1 867 ---

May 10 1 1358 ---

June 30 7 178 141.13 48 454

August 15 2 117 66.47 70 164

September 15 1 47 ---

December 15 2 117 36.77 151 203

December 30 4 165.5 115.37 62 305









Female Sexual Cycle

Ovaries are difficult to distinguish from testes in lizards less

than one year of age, however the obvious presence of oviducts in

females allows accurate sexing of even hatchlings. Immature ovaries

contain numerous follicles up to 4 mm in diameter. Maximum follicular

diameter in mature females between oviposition and spring recrudescence

is also approximately 4 mm (Figure 14). Yolking of follicles begins

between January 1 and March 1 and continues until ovulation in early

May. Maximum follicular diameters reach 30 mm at that time.

Seasonal combined ovarian weights reflect the same trends as

follicular diameters (Figure 15), with ovarian weight maxima (63.7 gm

in a 248 mm SV lizard with five enlarged follicles) in mature females

occurring in early May and post-reproductive minima (generally less than

0.35 gm) from July through December. The maximum combined ovarian

weight recorded in an immature (184 mm SV) female was 0.275 gm in March.

Immature weights were normally considerably less than this. Perhaps

her ovaries were developing in preparation for breeding the following

year when she would surely be of adult size.

Oviducal eggs were not present before at least the last of April

and were noted only as late as June 9. Yolked follicles and oviducal

eggs were never found in the same female and no yolked follicles (except

an occasional atretic one) were found in post-ovipository females.

Fresh corpora hemoragica averaged 6 mm in diameter, but regression was

rapid and corpora lutea were usually unidentifiable by early September

(Figure 16).

Of only two females with oviducal eggs, one showed evidence of

transuterine migration of ova. The right reproductive tract of that






















N



EGG DIAMETER


*
0
* 4


09


J F M A M J J A O N D


Figure 14. Seasonal variation in maximum follicle diameter (mm) in
ovaries of female Cyclura carinata. Small dots indicate individual
females; large dots, two or more lizards. M and N mark mating and
nesting seasons, respectively.































Figure 15. Seasonal changes in proportional ovarian weight (grams
x 10-4/SV in mm) in mature female Cyclura carinata. Each point
represents one individual lizard.







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female included two corpora lutea in the ovary and three eggs in the

oviduct; the left tract bore four corpora lutea and three oviducal

eggs. Cuellar (1970) has previously discussed this phenomenon in

lizards.

Minimum sizes for mature females (as indicated by the presence of

yolked ovarian follicles, oviducal eggs or corpora lutea) were 184 mm SV

(250 gm; with enlarged yolked follicles), 190 mm SV (280 gm; corpora

lutea present), 194 mm SV (live weight unknown; with corpora lutea),

and 197 mm SV (205 gm; with corpora lutea). Maturity of young adult

and subadult females collected between September and January could not

be accurately determined due to the regressed state of the ovaries

even in obviously adult females. The largest immature females collected

between January and August were 210 mm SV (approximately 320 gm), 191

mm SV (240 gm) and 184 mm SV (weight unknown). Maturity in females at

185-200 mm SV (200-300 gm) at an age of about six years (see GROWTH)

is indicated. Nearly all females presumably oviposit their first

clutch of eggs between age six and seven. Adult females averaged 225.4

mm SV (190-292) and 475.6 gm (205-1135) body weight.


Courtship and Mating

From late March through April, males became increasingly interested

in females. During April, males were frequently observed following

females on the ground. At this time, the resident territory-holding male

typically approached within one meter of the female, but did not display

or otherwise court the female. The approach usually caused the female

to headbob (submissively; see SOCIAL ORGANIZATION), move a short distance

away, stop, and again bob to the male. The male often reciprocated with










a headbob, and again approached the female closely and the sequence was

repeated (up to a dozen times). The impression was that the male was

attempting to insure his proximity to a female as the mating season

approached. Perhaps this precourtship interest is necessary for the

induction of receptivity as in Drosophila melanogaster (see Parker, 1974,

p. 158) and Anolis carolinensis (Crews, 1975b).

Resident males terminated their female-directed activity to displace

neighboring males from their (the resident's) territory (hence away from

the female) at this time of the year, just as they did during the

remainder of the year. However, it was my subjective opinion that the

males were more willing to defend at this time of the year than at any

other. There was no question that the general level of activity was

greatest at this time of the year (see ACTIVITY AND MOVEMENTS). Follow-

ing defense, the resident male returned to the female and resumed his

interest in her. The precourtship approach behavior could be a mechanism

by which a female can determine the extent of the territory and the

effectiveness of its defense by a potential mate.

In some cases, the male was so persistent in his attempts to

closely approach the female, that she ultimately moved out of his

territory and into that of a neighboring male. However, females some-

times also moved between males' territories without this pressure from

the resident males. Perhaps female Cyclura were making active choices

among courting partners at this time, as Trivers (1976) suggests for

Anolis garmani.

The interest of males in females increased through April, pre-

sumably until the female tolerated the close approach of a male and

active courtship could proceed. Unfortunately, neither active court-










ship nor copulation was observed in nature. However, they were fre-

quently observed in captivity and the basic behavioral components are

undoubtedly the same as those in non-captives.

Courtship was observed nearly 100 times (three times to completion)

in the captive enclosure in Gainesville during nine days between April 24

and May 9, 1975 (Table 7). During this period, four mature females

and at least two of four males were confined together in a pen at any

one time. The lizards were captured April 5-9, 1975, on the study

islands. The females and smallest male (#4) were released into the

captive enclosure on April 17, while the other males were maintained

separately in the laboratory. These males were introduced into the pen

at various times between April 24 and May 9 to investigate dominance

relationships (see SOCIAL ORGANIZATION).

Successful mating behavior can be divided into four basic stages:

approaching, displaying, neck holding, and copulating. Figure 17

illustrates the male and female components of courtship behavior.

Approach. In captivity the male and female did not always exchange

headbobs prior to the male's approach to the female. In the field, the

female always bobbed submissively at the appearance of the male; the

male often did not reciprocate (see SOCIAL ORGANIZATION). The court-

ing male typically approached the female laterally and from behind

(their bodies aligned at approximately a 30 to 450 angle). The profile

of the approaching male once within 0.5 m of the female was very low to

the ground. The body was dorsally-ventrally flattened and the chin was

kept less than 5 cm from the substrate. A few times the male turned

his head to inspect the female's hip area, but usually approached until

his head was lateral to the anterior trunk region of the female. At



















Table 7. Average number of courtships per day attempted by each
male of each female in Gainesville enclosure during nine days
between April 24 and May 9, 1975.


MALES
#1 #3 #4
SV
FEMALES1 (mm) 349 286 219

#1 235 3.0 2.333 4.75

#2 235 1.67 1.222 0

#3 216 1.33 1.222 0.75

#4 185 -- 1.000 0.75

Days male 3 9 4
present


IAll females were present everyday.






























Figure 17. Behavioral components of courtship in Cyclura carinata.














Courtship Ethoqram


Display -. Bob
------- -(submissive; on O's approach)



Approach
(with or Complete rejection
without bob) --- (moves away)

Maintain position


Vibratory Phase
(while approaching) Rejection
(runs away; usual ly with open-
Smouthed bobs)

Maintain position


Straddle and neck bi te

I Return bite

Release neck hold -

SEscape reaction
(with open-mouthed bobs)


Dragging phase

Ta il I maneuver


Refusal to arch tail
S(possible only if 0 small)

Tail arch
(Acceptance)


Opposition of cloacae
IT IITROM ISSION
--aTail Wiggle

Withdrawal


TERMIIIIIArlO OF MATING










this point the female often moved away, rejecting the male's advances.

If she did not (or could not, as in some captive situations) the male

began his courtship display and continued to approach the female.

Display or Vibratory Phase. The courtship display of Cyclura

carinata w'as stereotyped and very similar to that of most other iguanid

and agamid lizards that have been studied (Carpenter, 1967; Gonzales,

1974). The male continued his approach toward the female while rapidly

vibrating his head vertically. I have termed this behavior vibratoryy'

display due to the low amplitude of the headbobs. A typical display

action pattern (DAP; see Carpenter and Grubitz, 1961) of this head move-

ment appears in Figure 18. Four videotaped displays, each including four

oscillations of the head, averaged 0.36 seconds (0.32-0.40). Additional

amplitudes required proportionately longer during several other displays.

Males sometimes performed displays with open mouths.

This vibratory courtship display is synonomous with the "jiggling"

display described by Evans (1938) and Ruibal (1967); the "courtship

nod", by Carpenter (1962b); and the "shudder sequence", by Ferguson (1970)

for other lizards. In each case, the display consisted of a sequence of

shallow, rapid headbobs. Male Ctenosaura pectinata (Evans, 1951) and

Amblyrhynchus cristatus (Carptenter, 1966) also exhibit a similar court-

ship display. Sauromalus obesus (Berry, 1974) is the only iguanine

lizard studied to date that lacks this display.

Females rejected male courtship advances by a stereotyped rejection

display or by simply running away. Either behavior was accompanied by

vigorous headbobbing, typically with an open mouth. In the rejection

display (Figure 19), the female compressed her body laterally, postured

high on all four legs with her back strongly arched and her tail on the








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ground, and headbobbed rapidly (usually with open mouth). In the field,

as in many of the captive courtships, this display is probably sufficient

to thwart the males' courting interests. However, captive males often

continued the courtship sequence despite this display. If the female

maintained her position during the male's vibratory display and approach,

the male terminated the display, raised up and gripped the female's neck

in his teeth.

Many iguanid lizard species have a similar rejection posture

(Fitch, 1956; Clarke, 1963; Carpenter, 1967). Noble and Bradley (1933)

first described and illustrated this behavior but were unable to deter-

mine its significance. Within the subfamily Iguaninae,Sauromalus obesus

(Berry, 1974) also uses this rejection posture, while Amblyrhynchus

cristatus apparently does not (Carpenter, 1967); other members have

not been sufficiently studied.

Only one homosexual courtship (with the smallest male) was

observed and it was terminated by the courting male following his

vibratory display.

Neck holding. Following the vibratory phase of courtship, the

male moved to straddle the female and secure a mouth grip on the dorsal

region of the female's neck. The female could still terminate the

courtship at this point by turning and biting at the male's head and/or

struggling free. Females sometimes attempted to walk away, dragging the

male for short distances.

Once the female's neck was securely held, the male attempted to

maneuver his tail under that of the female to align the cloacae. The

receptive female then arched her tail upward to facilitate the male's

tail maneuvering. She could apparently still reject the male's advances,










by refusing to arch her tail, only if the courting male was smaller than

herself; large males could force their tails under the female's tail

even if she did not arch it. This was observed once in captivity during

the forced copulation (rape) of one of the females (discussed later) by

a large male. The refu-al of a female to arch her tail to allow

cloacal apposition was observed six times when a small male (219 mm SV)

had obtained a neck grip on a larger female. Once the cloacae were

finally opposed, the neck grip was maintained until hemipenial with-

drawal following copulation. The mating posture was exactly like that

pictured for Amblyrhynchus by Schmidt (1935).

Copulation. Once the cloacae were opposed, intromission followed

immediately and lasted from 40 to 76 seconds (Mean = 58.7; N = 3). No

thrusting by the male was observed. Wiggling of the distal portion of

the tail by the female immediately preceded withdrawal of the penis by

the male. Uncoupling was rapid; the male released his neck grip and

backed away from the femle. His pelvis remained elevated from the

ground until his hemipenis was fully retracted. Typically both lizards

then moved very little and rested quietly. Their activity during the

remainder of the day was generally depressed.

In all iguanine lizards except Iguana iguana, for which data are

available (Table 9) copulation (i.e. female receptivity) occurs approx-

imately one month before oviposition. A distinct relationship with the

fer.,ale ovarian cycle is implied. It is suggested, but not known, that

receptivity in Cyclura carinate immediately precedes ovulation as it

does in Anolis carolinensis (Crews, 1973a). and perhaps Crotaphytus

wislizeni (Parker and Pianka, 1976).










It could not be determined if female receptivity is terminated by

copulation as Crews (1973b) has shown to be the case in Anolis

carolinensis, but it is strongly suspected. One captive female was

copulated with twice by the same male in a period of three days, however

she was an unwilling partner in the second mating. The male was able

to "rape" the female due to his much larger size (286 mm SV versus

235 mm) and the confinement of the enclosure. Since no female Cyclura

was observed to accept a male more than once in captivity (mated females

always rejected further courtship attempts), I suspect that females

copulate only once, with only one male, during each breeding season.

Males, however, will copulate more than once during the breeding

season, but apparently only once during any one day. On April 24, male

#3 had attempted to mate once (with another female) before he copulated

successfully with female #1. He did not attempt courtship again that

day. The following day he unsuccessfully courted three times. The

next day he attempted to breed eleven times (with two females) before

he forcibly mated #1 female. He did not try to court again that day,

but did on several following days. On May 9, #3 male copulated success-

fully with the first female (#3) he courted. She was very receptive and

moved to him immediately after his morning emergence. He did not attempt

courtship for the remainder of the day. It is suggested that males in

the field are able to mate with more than one female if they are avail-

able.

In captivity, female #1 accepted male #3 on April 24, and was

raped (by the same male) on April 26; female #3 accepted male #3 on

May 9. The other two females were not observed to accept males, but

both shelled eggs. It is therefore presumed that they also mated. The










earliest courtship attempt was observed on April 24; none were attempted in

two days of observation prior to that. Since the lizards involved were

captured less than three weeks prior to that time, a two to three week

mating season, centered about the first of May, is indicated.

Post-Copulatory Behavior. Captive males frequently dragged their

cloacal regions on the substrate both prior to and following courtship

behavior. Two captive males also exhibited a strange modification of

normal defecatory behavior during the breeding season. The pelvic

region was elevated above the ground in typical defecation posture;

however, the abdominal contractions necessary to egest the fecal pellet

resulted in version of the hemipenes. The organs remained everted until

after the scat was deposited. As they were then withdrawn a small

quantity of white viscous fluid (semen?) dripped from the region of

each retracting hemipenis. 'I could not determine the significance of

this behavior.

Probably the most significant post-copulatory behavior noted in

the captive situation was when the male drove off males that courted

the female with which he had copulated. Unfortunately, this behavior

was clearly observed after only one of the captive matings. Following

the other two copulations, other males did not attempt to court the

mated female.

Two other mlaes were present in the enclosure at 1237 hours on

April 26, 1975, when male #3 copulated with female f#. Male #2 was

old, senile, and subdominant to #3; he was never observed to court

any females. Male #4 was very young (first or second year post-maturity);

he courted frequently (Table 7) but was never accepted by a female.










Approximately eight minutes after #3's copulation, male #4 courted

female A4 twice in less than 30 seconds and was rejected each time

following the vibratory display. Male #3, resting in the shade, showed

no interest in this activity. However, at 1249, #4 approached female

#1 very rapidly and after an abbreviated vibratory display, jumped up

and bit at her neck. Simultaneous with her attempts to reject him,

#3 postured (see SOCIAL ORGANIZATION) and charged from his resting

place and chased #4 away from "his" female. Following the short chase,

#4 bobbed submissively, as #3 moved back to his resting place. Within

30 seconds, #4 again moved to court #1 and again #3 postured, charged,

drove #4 from the vicinity of the female, and moved into the shade to

rest. This same sequence was repeated five times over the following

five minutes; 20 to 60 seconds separated each sequence. At that time

(about 1256 hrs), male #2 moved to the feeding station and this seemed

to stifle #4's advances temporarily.

No interaction occurred until 1321 when #4 resumed his courting

interest in #1 and #3 again chased him away from her. The sequence was

repeated six more times, each separated by 60 to 150 seconds, over the

next nine minutes. Male #4 dragged his cloaca on the substrate three

times during the following nine minutes and retreated to a burrow for

the remainder of the day at 1341 hrs. Number 3 male did not attempt

to "guard" any female during any other day of observation. This pro-

tective behavior thus appears to be restricted to the day of copulation.

Assuming females are receptive for only a short time during the

ovarian cycle, the practice oF guarding a recently-copulated female by

a male in the field would help guarantee that he, alone, contributed to

that female's entire brood that year. Parker (1974) has discussed the










significance of this behavior in his theoretical treatment of female-

guarding as a male time-investment strategy.

The mating system of Cyclura carinata is apparently primarily

monogamous with serial polygyny among some males (see Wilson, 1975).

There appears to be pair-formation during at least the breeding season.

Two females at the SW Blind lived within the home range of the same

respective males for two years until all were killed by dogs and cats.

Monogamy and/or polygyny seem to be the predominant systems among the

iguanines. Although no breeding observations were made, pair bonding

and monogamy have been suggested for Cyclura pinguis (Carey, 1975).

Johnson (1965) noted male-female pairing in Sauromalus obesus, but did

not observe courtship. In a more complete behavioral study, Berry (1974)

found a polygynous system with pair formation for the same species.

Male Mona Island Cyclura cornuta are generally polygynous but some

are apparently promiscuous; females are monogamous, polyandrous, or

promiscuous (Wiewandt, in preparation). Street (1952) implied that

Cyclura nubila is promiscuous, but no supporting data were presented.

His observations were based on tame, unrestrained lizards inhabiting a

golf course in Cuba, but may not be representative of field populations.

Alvarez del Toro's (1972) observations of Iguana iguana suggest a

polygynous mating system for the species. However, Peracca (1891,

cited in Noble and Bradley, 1933) observed that captive male iguanas

mated with more than one female, but did so more with one female than

another. He also noted multiple insemination of females (up to eleven

times). This suggests a polygamous if not totally promiscuous system,

but it may have been an artifact of the captive situation. Mueller

(1972) reported that the species is polygamous in Columbia. Further









studies of courtship behavior as well as all aspects of social behavior

are sorely needed for lizards of this subfamily if meaningful comparisons

are to be made.


Nesting

Female Cyclura carinata oviposit their single annual clutch in

early June. Two gravid Pine Cay females had fully shelled oviducal eggs

on June 3 and 9 and four recently deposited nests were excavated on June

5, June 7, and June 9 (2) on Pine and Water Cays. A female at the SW

Blind site laid her eggs June 6. A female captured June 5 on Water Cay

nested in an observation pen four days later. Captive lizards tended

to nest later than native lizards, perhaps due to subnatural thermal

regimes. A Pine Cay female collected April 4 deposited her clutch on

June 12 in Gainesville. A Water Cay female, captive for nearly one year,

dropped her eggs on July 25, 1975 (David Auth, personal communication).

Soil for burrowing was not available in the pen in 1975 and the eggs

were deposited on the enclosure's substrate. The female had ceased

feeding two weeks previous to oviposition and resumed immediately after

laying.

Since copulation was not observed in the field, I have no way of

knowing with certainty the relation of a female's nest site to the

territory of the male with which she copulated. However, burrows, or

branches thereof, offering optimum nesting conditions (see later) are

limited in many areas due to substrate conditions and high lizard

densities. Therefore, female nest site location is probably not

closely determined by the location of the territory of the male with

which she copulated, but rather by nest site availability. A clustered




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