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Group Title: Atlantic loggerhead sea turtle, Caretta caretta caretta (L.), in America (FLMNH Bulletin v.4, no.10)
Title: The Atlantic loggerhead sea turtle
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00001554/00001
 Material Information
Title: The Atlantic loggerhead sea turtle Caretta caretta caretta (L.) in America
Series Title: Florida. University, Gainesville. State Museum. Bulletin. Biological sciences
Physical Description: 294-348 p. : illus. ; 23 cm.
Language: English
Creator: Caldwell, David Keller, 1928-
Publisher: s.n.
Place of Publication: Gainesville
Publication Date: 1959
Subject: Loggerhead turtle   ( lcsh )
Genre: bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Included Bibliographies.
Statement of Responsibility: by David K. Caldwell and others
 Record Information
Bibliographic ID: UF00001554
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: ltqf - AAA0863
notis - ACK0929
alephbibnum - 000440463
oclc - 05069385
lccn - a 59009671

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Full Text







David K. Caldwell, Archie Carr, and Larry H. Ogren
David K. Caldwell, Frederick H. Berry, Archie Carr, and Robert A. Ragotzkie
Abridged and annotated by David K. Caldwell




Volume 4

Number 10

BIOLOGICAL SCIENCES, will be published at irregular interva. Veh"Ln
will contain about 300 pages and will not necessarily be completed i my one
calendar year.

Or.rvE L. AUSTIN, JR., Editor

The publication of this number of THE BUL-
LETIN has been made possible by a grant
from the Graduate School, University of Florida.

All communications concerning purchase or exchange of the publication should
be addressed to the Curator of Biological Sciences, Florida State Museum, Sale
Building, Gainesville, Florida. Manuscripts should be sent to the Editor of the
BULLETIN, Flint Hall, University of Florida, Gainesville, Florida.

Price for this issue $.70

Published 3 June 1959



When the series of studies now being carried on under National
Science Foundation sponsorship (NSF project G-1684 and G-5479,
principal investigator Archie Carr) was planned it was proposed that
the Atlantic green turtle, Chelonia mydas mydas (Linnaeus), be made
the central subject of the research. The herbivorousness of green
turtles was visualized as imposing on them a distinctive way of life,
involving long periodic journeys between feeding and breeding
grounds. This, in turn, was seen as a unique attribute, setting
Chelonia off from other sea turtles-making it easy to study because
it gathers to breed in rookeries, and especially interesting because the
journeys to and from the rookeries posed special problems of orienta-
tion and suggested that Chelonia must have an extraordinary capacity
to navigate. While all this still seems true, it is now clear that dif-
ferences among sea turtles with respect to reproductive travel are
less than was supposed.
Data from a tagging program at Tortuguero, Costa Rica, have
been strengthening the credibility of fishermen's tales of navigatory
feats by green turtles. These stories constituted the original assump-
tion to be tested by the Tortuguero studies, and while final proof of
their authenticity will be difficult to get, there remains no real doubt
of their essential truth. While the case for the navigatory prowess
of Chelonia has been growing, information from various other sources
has suggested that all sea turtles migrate.
The following suite of papers supports our belief that the life
cycle of the carnivorous Atlantic loggerhead, Caretta caretta caretta
(Linnaeus), may in most ways be much more similar to that of the
green turtle than we imagined. Like the green turtle, the loggerhead
travels far, it travels in groups, it emerges more than once to complete
a season's laying, it tends to return to the same place for successive
layings and is able to locate these sites with some precision, and its
breeding range includes places where aggregated nesting occurs as
well as sites of separate emergence by lone individuals. Details of
nesting and development of the young and their early behavior also
are surprisingly similar for all the sea turtles.


To most people, including most zoologists, the loggerhead is an
animal to be seen on the sea beach as a nesting female or an emerging
hatchling, or at shipside or dockside as a big head stuck up out of the
water to breathe. We really know almost nothing about what goes
on between these few points of our contact with the animal. Though
the information that can be added is fragmentary, it fits in with the
fishermen's stories and our growing belief in the essential consonance
of the life cycles of all the sea turtles.
The three papers on loggerheads included in this series were pre-
pared independently. They are closely related, even overlapping in
some aspects, and it was felt that workers in herpetology and marine
ecology would find it convenient to have them available under one
cover. We, and the various other authors, are indebted to our re-
spective organizations for permitting, and to the editorial staff of the
Bulletin for countenancing this unorthodox style of presentation.
David K. Caldwell, United States
Fish and Wildlife Service,
Archie Carr, University of Florida,
March, 1959

Vol. 4



SvNOPSIS: Tagging evidence shows that female Atlantic loggerhead sea
turtles may travel as much as 1000 shoreline miles away from the nesting beach
in 10 months.
The nesting procedure of the Atlantic loggerhead is described and illustrated.
The loggerhead sometimes nests singly, but more often in aggregations on re-
stricted stretches of beach. Loggerheads mate in the water just oil the nesting
beach, though whether before or after nesting, or both, is still unknown. No
correlation exists between the size of the turtle and the time of laying or the num-
ber of eggs laid.
The principal nesting range of the subspecies is the mainland coast of North
America from about Cape Lookout, North Carolina, to Mexico; emergencies have
been recorded occasionally on certain northern Caribbean islands and as far
south as Costa Rica. The Atlantic and Pacific subspecies of the loggerhead can-
not be separated by their marginal lamninae.

Despite the large size of the Atlantic loggerhead turtle, Caretta
caretta caretta (Linnaeus), and its common occurrence along heavily
populated shores, its movements and certain details of its nesting
habits are still poorly known. This is an account of recent observa-
tions on the species' nesting and of results of tagging operations on
the coasts of Georgia and Florida.


Long Range Travel

It has long been suspected that the stray loggerheads found oc-
casionally in European waters were individuals from American waters,
where the nearest upstream nesting grounds lie (in relation to the
Gulf Stream). Although it may never be possible to prove the Amer-

Field work supported in part by National Science Foundation Grants G-1684
and G-5479 (University of Florida, Principal Investigator Archie Carr). Contribu-
tion number 42 from the United States Fish and Wildlife Service Bureau of Com-
mercial Fisheries Biological Laboratory, Brunswick, Georgia.
SFishery Research Biologist, United States Fish and Wildlife Service Bureau
of Commercial Fisheries Biological Laboratory, Brunswick, Georgia; Collaborator,
Florida State Museum; Collaborator in Ichthyology, Institute of Jamaica.
Professor of Biological Sciences, University of Florida; Associate, Florida
State Museum; Hescarch Associate, American Museum of Natural History.
Formerly Research Assistant, University of Florida. Present address: Peace
River Park Museum, Bartow. Florida.


ican origin of the European loggerheads, and while it may eventually
be shown that they derive from downstream rookeries, on the Mediter-
ranean coasts for example, we now at least have a tag return which
proves an impressive distance traveled between known points during
a known period of time.
The turtle recovered was a female with a carapace length (meas-
ured as described by Carr and Caldwell, 1956: 4) of 35 inches, tagged
by Caldwell and Thomas R. Hellier, Jr. while nesting at Hutchinson's
Island, opposite Jensen Beach, Martin County, Florida, on 27 May
1957. It was recaptured by a shrimp trawler off the mouth of the
Mississippi river, probably near Pass-a-Loutre, about 24 or 25 March
1958. It was thus at liberty for about 302 days and was retaken
about 1000 shoreline miles from the place of tagging. To reach the
point of recapture by the shortest route without crossing the open
Gulf, this turtle had to travel southward around the tip of Florida and
then northward and westward into the north-central Gulf of Mexico.
The length of time between tagging and recapture suggests the animal
may have taken a more circuitous inshore route. Although the trip
might seem to imply continuous travel against the Gulf Stream, an
examination of major seasonal current systems in the Gulf of Mexico
(as given by Leipper, 1954: 121-122) shows that the turtle might
actually have been helped by currents. Caldwell, Berry, Carr, and
Ragotzkie (1959 herein) show that loggerheads nest more than once
a season. Although by no means proved, it also seems likely that they
remain in the general vicinity of the rookery area throughout the
nesting season, or until late summer. If this turtle left the Jensen
Beach area in late August, it could have passed around the southern
tip of Florida free of opposition by the Gulf Stream simply by staying
close inshore until it reached Florida Bay. From the southeastern
Gulf of Mexico the currents flowing generally northward and west-
ward along the eastern Gulf coast in the late winter and early spring
could have helped it reach the Mississippi by March. This is one of
the longest journeys ever proved for any reptile, being rivalled only
by trips made by female green turtles tagged in Costa Rica (Carr
and Ogren, Ms.).
The only other tagged loggerhead recovered an appreciable dis-
tance from where it was marked made a much shorter journey in
much less time. Caldwell, Carr, and Hellier (1956b) reported an
individual tagged when nesting at Fort Pierce, (Hutchinson's Island,
Florida), and recaptured 3 weeks later by a shrimp trawler off Day-
tona Beach, Florida, some 130 shoreline miles northward. The re-

Vol. 4


cover indicates that mature loggerheads may travel considerable
distances in a fairly short period of time. This turtle, like the other,
could have been helped by ocean currents, in this case the northward-
flowing Gulf Stream.

Movements of the Hatchling
One of the major problems in the study of sea-turtle life histories
is the question of where the post-hatchlings spend the first months
after they leave the nest. It has been pointed out (Deraniyagala, 1939;
Carr, 1952) that small specimens of the Atlantic ridley sea turtle,
Lepidochelys kempi (Garman), occasionally reach points far distant
(England, for example) from their probable natal beaches. Such oc-
currences suggest a passive migration in the form of a post-hatchling
drifting in the major ocean currents, the Gulf Stream in particular.
The ridley is the only species in which this conjecture has been sup-
ported by concrete evidence, and even this is meager.
We know of no previous records of sea turtle hatchlings taken
away from a nesting beach or at sea. Two recent captures are thus
of interest. William W. Anderson took a young loggerhead in a
dipnet at the surface in 200-fathom water at 250 10' N., 800 02' W.,
about 15 miles southeast of Key Largo, Florida, 26 July 1957. This
animal, now in the collection of the Bureau of Commercial Fisheries
Biological Laboratory at Brunswick, Georgia, still has its egg tooth
and umbilical scar and measures 64 mm. in carapace length. Two
other hatchlings, one badly macerated, the other in fair condition,
were taken from the belly of a 7-foot female white-tipped sharp (Car-
charhinus longimanus) caught at 300 50' N., 780 45' W., 135 miles
due east of Cumberland Island, Georgia, 22 August 1957. These spec-
imens, now in the University of Florida Collections, show juvenile
characters and measure 47.5 mm. in carapace length. They were
sent us by Dr. Richard Backus of the Woods Hole Oceanographic In-
stitution, who has been consistently generous with sea turtle data
gathered incidental to his oceanographic studies.
Comparison with captive loggerheads of known age (cf. Caldwell,
Carr, and Hellier, 1956b: 297) suggests the first specimen was about
11 weeks old, the second two about 12 to 13 days old when eaten.
Whether these turtles were lost waifs drifting to oblivion in the open
sea, or whether they occur in these localities regularly after leaving
the nesting beaches is still uncertain. If they occur in these waters
regularly, it is strange that the biologists who have spent hundreds
of hours observing and dipnetting there have reported no others.


Colonial Nesting
Although the loggerhead nests on the beaches of all the coastal
South Atlantic and Gulf states roughly from Cape Lookout, North
Carolina, to Texas, it apparently concentrates its nesting activity in
restricted areas which may conveniently be termed "rookeries." Sim-
ilar rookeries are known for other species of sea turtles, particularly
the green turtle. We have found three such nesting concentrations
of loggerheads on the Atlantic coast of the United States; one is
Hutchinson's Island, Florida; another is Jekyll Island and the adjacent
Little Cumberland Island near Brunswick, Georgia; the third is Cape
Romain, South Carolina, fortunately located within a United States
Fish and Wildlife Service wildlife refuge. Aerial reconnaissance of
the coast of Florida north of Matanzas Inlet, of the entire coast of
Georgia and of most of that of South Carolina, has shown the apparent
concentration of nesting activity on Jekyll and Little Cumberland
Islands and at Cape Romain to be real. While a few nests were ob-
served scattered along the entire stretch of coast, each flight showed
the places mentioned to be far more heavily used than any other area.
Surveys of the south Florida coast indicate that Hutchinson's Island
is similarly important as a rookery.
In addition to the concentration of tracks seen from blimps on
Jekyll and Little Cumberland Islands, evidence that these islands
near Brunswick are used as a rookery has been supplied by William
W. Anderson. While conducting shrimp studies for the Fish and Wild-
life Service with the Brunswick shrimp fishery off the Georgia islands,
particularly from 1930 to 1938, he found loggerheads quite rare in the
area each year during the fall, winter, and early spring. In late spring
as the summer nesting season approached, the turtles appeared in
large numbers in these particular waters, and were seen nowhere
else in abundance, neither off neighboring islands nor in the sounds
and passes. The turtles off Brunswick were at times plentiful enough
to be a nuisance to the shrimp fishermen whose trawls they damaged.
As shrimping continued after the turtle nesting season, it provided
a good sampling opportunity, which indicated a real influx of mature-
sized loggerheads from outside the rookery area during the nesting
season. Brunswick shrimp fishermen working today say that although
the total loggerhead population has been reduced, this same season-
ality in abundance occurs.

Vol. 4


In both the Atlantic and Pacific green turtles mating occurs mainly
off the nesting beach (Harrisson, 1954; Carr and Giovannoli, 1957: 30.).
William W. Anderson's observations suggest that similar behavior is
characteristic of loggerheads. He had excellent opportunities be-
tween 1930 and 1938 to observe the turtles clearly from his slow-
moving trawler, and states that he often saw loggerheads mating in
the water just off the Georgia beaches, particularly near the passes
between the sea islands where the beaches are located. Not being
aware at the time of the scarcity of such data, Anderson kept no
records of dates, but he clearly recalls that this mating behavior
took place each year he worked in the area, and always during the
nesting season of the loggerhead. His observations agree with those
of others that mating loggerheads tend to ignore a nearby boat. He
never saw mating turtles in threes-a female with two attending
males-as has been reported for the green turtle by Carr (1956) and
by Carr and Giovannoli (1957: 31); although elsewhere we have been
told of observations of such trios of loggerheads (see also Caldwell,
1959, herein).
Anderson noted that the influx of turtles to the waters off the
nesting beaches began as much as a month before actual nesting.
This fact may bear on the problem of whether mating occurs just be-
fore laying or afterwards, a detail not yet determined for any species
of American sea turtle (Carr and Giovannoli, 1957: 31; Carr and Ogren,
Nest Building and Oviposition
Although the nesting of the Atlantic loggerhead frequently has
been described in popular articles, the only accounts in zoological
literature that recount the process in detail arc the composite descrip-
tions of Mast (1911) and Carr (1952: 390). After observing nesting
loggerheads for several seasons we find that these accounts require
modification. Accordingly we present the following description of
the nesting of the Atlantic loggerhead and the accompanying series
of photographs showing some of the more important details. Both
the notes and pictures are composites, because it is difficult to find
turtles just emerging from the sea and to follow and photograph the
entire procedure of a single individual. However, the behavior was
so similar in all localities and at all times of the nesting season that
the account given here is believed to be representative of the Atlantic
loggerhead on the coasts of Florida and Georgia.



Figure 1.-Nesting Atlantic loggerhead, showing large excavation made pre-
liminary to actual digging of nest (see text).
Figure 2.-Flipper inserted into growing nest cavity.
Figure 3.-Flipper lifting sand out of nest cavity.
Figure 4.-Left flipper digging, right flipper flat on sand.
Figure 5.-Head down and neck arched prior to laying. Note open eye and tears.
Figure 6.-Hind flippers raised before group of eggs is extruded.
Figure 7.-Hind flippers lie flat on surface of sand during intervals between
extrusions of eggs.
Figure 8.-Head raised between extrusions of eggs. Note tears and open eye.


On first leaving the water, and even until she has started to dig,
the turtle is easily disturbed. She reacts strongly to a light thrown
directly upon her. Contrary to Carr's--accunt (1952: 390), after the
site for the evening's activity is selected all turtles observed dug a
preliminary excavation of varying extent. The female uses all four
flippers in this process until she has lowered herself several inches
below the surface of the sand (Figure 1). Digging of the actual nest
follows almost immediately, for which only the hind flippers working
alternately are used. With its outer edge downward, one flipper is
inserted into the sand or into the growing hole (Figure 2). It is then
cupped, and the outer edge is rotated inwardly. A small amount of
sand is now scooped up (Figure 3), lifted to the top of the hole, and
deftly laid to one side. Meanwhile the opposing flipper remains flat,
"palm" down on the sand near the edge of the hole (Figure 4). The
turtle now shifts her body so this other flipper comes into position
over the hole. Just before she inserts it into the hole to dig, she flicks
it out laterally and upward to brush the loose sand, deposited when
this flipper last excavated, away from the edge of the hole. This tech-
nique differs only in minor points from that described for the green
turtle by Carr and Giovannoli (1957: 25).
The digging process is then repeated as the turtle shifts to bring
the first flipper into play again. Almost as soon as the nest is finished
the flippers are laid straight back or pointed slightly outward, "palms"
down (Figure 7), and the cloacal "ovipositer" is inserted. During the
digging process the head has been held flat on the sand and the eyes
kept open, although blinking occasionally. The eyes secrete copiously
(Figures 5 and 8) during the digging and laying. Just before each
group of eggs falls (in groups of one, two, or three) the neck is arched
with the head still down (Figure 5), and the hind flippers are raised
slightly (Figure 6). As each group of eggs falls, the neck is lowered to
the position held during digging and the flippers come down and
lie flat again between extrusions (Figure 7). During this interval,
the head may be raised slightly (Figure 8) and the turtle may snort
or sigh by expelling air from her nostrils or month.
Carr and Giovannoli (1957: 25) stated that the loggerhead will
press its vertically oriented back flippers against the upper part of the
wall of the nest cavity "as if to keep sand from falling in," and-Carr
(1952: 11) illustrates the maneuver in Lepidochelys. Despite numerous
attempts, we never succeeded in bringing about this behavior in a lay-
ing Atlantic loggerhead. Several times we dug part of the wall of the
nest away to reveal the eggs for photography, and never did the

L 1



A S'~
;,,. I-,


Figure 9.-Nearly cylindrical nest cavity almost filled with eggs.
Figure 10.-Rear flipper dragging sand to fill nest and cover eggs.
Figure 11.-Hind flippers packing sand in filled nest.
Figure 12.-Hind flippers packing sand in filled nest.
Figure 13.-All flippers sweeping sand to conceal the site.
Figure 14.-Turtle about to leave the nest. Note lifted head, open eye, and
prominent hyoid apparatus.
Figure 15.-Nest site after departure of turtle. Trail leads off to left.
Figure 16.-Turtle crawling to the surf after nesting. Note position of head.


, ww'~ L



turtle attempt to shore up the crumbling nest. Once when we moved
the posterior end of the turtle away from the nest opening she con-
tinued to lay on the surface of the sand beside it. When replaced
over the hole, she continued to lay as if nothing had happened.
When the nest is filled with eggs (Figure 9), covering begins almost
immediately. Sand is drawn in by the hind flippers, usually work-
ing alternately, sometimes together. The outer edge of the flipper is
used, the limb reaching well forward and out from the body to drag
sand back to the hole (Figure 10). As filling proceeds, the front flip-
pers join in sweeping sand backward to replenish that pushed into the
nest cavity by the hind legs and, like the hind flippers, the front ones
are used either alternately or together. When the hole is full of loose
sand, the hind flippers press it down firmly (Figures 11 and 12). Dur-
ing the filling and packing process the-head and fore part of the
body are sometimes raised as if to shift weight to the hind flippers
and help them exert more force. Perhaps this shifting and raising of
the body to increase pressure at the hind flippers accounts for the
impression that the site is "pounded." Although it was expressly
watched for, no turtle was seen to pack or pound the nest with her
plastron, as reported by Carr (1952: 391). As the filling reaches com-
pletion, the front flippers aided somewhat by the hind ones begin
to fling sand backward. This increased exertion pivots the turtle
on the pedestal of sand her digging leaves under her plastron.

Figure 17.-Arrival at water, snout lowered into surf.
Figure 18.-Head raised before turtle proceeds through surf.

After completing the nest the turtle rests for a short period, and
she also rests between the several subsequent outbursts of sand-flinging
before moving away from the site. The flinging of sand-presumably
aimed at concealing the site, and certainly effective-often enlarges
the preliminary excavation (Figure 13). Just as the turtle moves


away from the site she raises her head high with the eyes still open,
as they have been throughout the nesting process (Figure 14), and
the hyoid apparatus becomes quite prominent as it moves in and
out. When she leaves the nest, the site (Figure 15) is so camouflaged
that the eggs are hard to find without the aid of a probing rod.
The return trip to the surf is usually made quickly and purpose-
fully. Although the head is slightly raised while the turtle drags
herself along (Figure 16), on reaching the water she drops her head
into it (Figure 17). After a moment she raises it again (Figure 18)
before moving rapidly out of sight into the sea.
Agent Robert Kilby of the Georgia Game and Fish Commission
has told us of turtles completing the digging activity, laying a few eggs,
beginning to cover these, and then laying the rest of the complement
before finally covering the nest.
One collaborator let a turtle complete her nest, and when he
turned her to be tagged she played another mature egg. We allowed
one turtle to finish her nest and then killed her to examine her for
internal eggs. Though she had laid 90 eggs in a normal fashion and
covered her nest, she still retained two mature eggs in the lower
While the size of each egg in a clutch remains fairly constant,
unlike those of the leatherback, Dermochelys coriacea coriacea (Lin-
nacus), (see Caldwell, Carr and Hellier, 1956a: 282; Caldwell, 1959;
Carr and Ogren, in press) we twice found a single tiny egg in a
normal clutch at the Jekyll Island rookery. These small eggs, some-
what oblong and measuring about 20 mm. in their greatest dimension,
were fully shelled but contained no yolk and only a small amount
of albumen. It was not ascertained when they were deposited.

Time of Emergence
Nesting loggerheads usually come out of the sea shortly after
dark, and most of their nesting activities take place during the first
4 or 5 hours after dusk (see Caldwell, 1959, herein). As no case
of a loggerhead nesting after daylight has been reported in the lit-
erature, the following observations are of interest.
On 13 July 1958 Caldwell, in company with Frederick H. Berry
and Robert A. Ragotzkie, made a low-altitude aerial survey of the sea
beaches from Cape Remain, South Carolina, to Brunswick, Georgia.
At 0905 hours they observed a large loggerhead just returning to the
water after apparently having nested on a beach just north of the
inlet to Charleston Harbor, S. C. Official sunrise was 0500 hours and,

Vol. 4


as the day was clear, it was full daylight by 0545. The tide had just
turned to flood and, as the tracks leading out of the water extended
nearly to the water's edge, the turtle could not have been on the
beach more than the normal hour or so. From the air it appeared
that this turtle had started and completed a normal nesting during
full daylight.
During mid-July 1954 Agent Robert S. Pfister of the Florida State
Board of Conservation made a similar observation on Hutchinson's
Island about 1 mile south of the Fort Pierce Inlet where he had noted
little preivous nesting. A rather small turtle appeared on the beach
before sunrise when the dawn was just light enough so that "one
would not need lights to drive a car on the highway." The turtle
made a leisurely but direct trip to a spot above the high tide mark,
dug its nest, laid, covered the eggs, and returned to the water. By
then the sun had been above the horizon for a full hour.
A third instance, by coincidence also on 13 July 1958, was reported
by Agent Kilby, who saw a turtle on Jekyll Island covering her eggs
well after daylight. He believed that she must have left the water
at about 0530 to 0600 hours, well after daylight. Kilby found an-
other loggerhead after daylight on the south end of Jekyll Island
which he thinks was lost on the broad sand flat, for her back trail was
unusually long and meandering.
Agents Pfister and Kilby guard two of the three greatest logger-
head nesting grounds on the entire Atlantic coast of North America.
They patrol the beaches in their charge with motor vehicles nearly
every night throughout the turtle nesting season, from just after dark
to past dawn. They undoubtedly see most of the turtles that emerge
on their beaches, possibly more than are seen by any other men
Size of Nesting Females
Carapace lengths to the nearest one-fourth inch were recorded
for 110 turtles nesting on Jekyll Island from 29 May through 31 July
1958. The mean length was 373/4 inches, with a range of 31/4 to
451/4 inches. An analysis showed no correlation between the size
of the turtles (either mean or range) and the dates they nested.

Size of Turtle in Relation to Number of Eggs Laid
The number of eggs in 25 clutches was compared with the size
of the turtles laying them. Analysis of these variables showed no


Nesting Range
Each year since Carr's first visit to Tortuguero, Costa Rica, in
1953 the local turtle-turners there have reported the emergence of
a loggerhead or two among the green turtles, Atlantic hawksbills
(Eretomochelys imbricata imbricata (Linnaeus)), and Atlantic leather-
backs (Dermochelys coriacea coriacea (Linnaeus)). Though hundreds
of turtles were examined there during the tagging program (Carr and
Giovannoli, 1957; Carr and Ogren, in press; Carr and Ogren Ms.) no
loggerhead was found until the summer of 1957, when early in the
evening of 29 July a small (carapace length 34 inches) female came out
on the beach and was turned by Durham Rankin, a creole in the em-
ploy of the project (Figure 19). The southernmost previous recorded
emergence for the loggerhead was from the north coast of Cuba (Cald-
well, Carr, and Hellier, 1956b: 296), though Lewis (1940: 62) noted that
the species is reported to nest on the Cayman Islands.

L Al~
,s 0i


Figure 19.-Female loggerhead photographed on the beach at Tortuguero,
Costa Rica; the first emergence recorded for the species in American waters
south of Cuba.

The case presents an extreme example of the tendency, observ-
able in other species of marine turtles and mentioned earlier in this
paper as characteristic of loggerheads of the Atlantic coast, to nest
either in aggregations or as isolated individuals. Breeding aggrega-
tions of animals usually develop integrating bonds that place the

Vol. 4


aberrant individual with an urge toward solitary breeding at a selec-
tive disadvantage. The chances for consummation of any repro-
ductive venture apart from the group effort, especially when a long
migration to the nesting grounds is involved, would appear slight.
With the sea turtles we can at present only point out the phenomenon
and hope that with better understanding of the organization of the
breeding group an explanation will eventually emerge.

One character used to distinguish between the Atlantic and Pacific
subspecies of the loggerhead has been the number of marginal lam-
inae; the Atlantic form is supposed usually to have 12 on each side
and the Pacific race 13 (see, for example, Carr, 1952: 382). Counts
of the marginal laminate in two small groups of hatchlings, each group
from a single clutch of eggs and both from Jekyll Island, show this
character to be invalid. In one group 8 specimens had a 13-13 count,
4 a 12-12. The other group had 5 with a 13-13 count, 6 with 12-12,
and one with 13 on the left and 12 on the right.

We wish to thank the many people who furthered our studies with
information, physical aid, and encouragement. Some of these are:
Frederick H. Berry, Harvey R. Bullis, Jr., Rolland C. Byrd, Mr. and
Mrs. Henri Casanova, Hugh M. Fields, David Could, Evelyn Hellier,
Thomas I. Hellier, Jr., James R. Pearce, Teodoro Quiros C., and
Robert A. Ragotzkie.
We are grateful for the cooperation afforded the project in Georgia
by the United States Navy (Na\ al Air Station, Glynco) which granted
permission to make reconnaissance flights in their airships. David
Gould, Director of Coastal Fisheries for the Georgia Game and Fish
Commission, kindly allowed Caldwell to participate in patrol flights
by the Commission airplane. The pilot, Clifford G. King, was most
gracious in facilitating observations during the flights.
We are especially indebted to Agents Robert Kilby and Robert S.
Pfister, respectively of the Georgia Game and Fish Commission and
the Florida State Board of Conservation, for their untiring cooperation
in the field. Officials of both these agencies were most helpful in
granting us collecting and study permits. William W. Anderson gen-
erously furnished us with important unpublished notes on Georgia
sea turtles; and to him, to Frederick H. Berry, and to Jack W. Cehr-
inger we are indebted for critical reading of the manuscript.



Caldwell, David K.
1959. On the status of the Atlantic leatherback turtle, Dermochelys coriacea
coriacea, as a visitant to Florida nesting beaches, with natural history
notes. Quart. Jour. Florida Acad. Sci., vol. 21, no. 3, pp. 285-291, 1 fig.
Caldwell, David K., Archie Carr, and Thomas R. Hellier, Jr.
1956a. A nest of the Atlantic leatherback turtle, Dermochelys coriacea coriacea
(Linnaeus), on the Atlantic coast of Florida, with a summary of Ameri-
can nesting records. Quart. Jour. Florida Acad. Sci., vol. 18, no. 4,
pp. 279-284, 3 figs.
1956b. Natural history notes on the Atlantic loggerhead turtle, Caretta caretta
caretta. Quart. Jour. Florida Acad. Sci., vol. 18, no. 4, pp. 292-302,
2 figs.
Carr, Archie
1952. Handbook of Turtles. Ithaca, N. Y.: Comstock Publishing Associates,
xv + 542 pp., 37 figs., 82 pls., 23 maps.
1956. The Windward Road. New York: Alfred A. Knopf, Inc., xvi + 258
+ viii pp., illus.
Carr, Archie, and David K. Caldwell
1956. The ecology and migrations of sea turtles, 1. Results of field work in
Florida, 1955. Amer. Mus. Novitates, no. 1793, 23 pp., 4 figs.
Carr, Archie, and Leonard Giovannoli
1957. The ecology and migrations of sea turtles, 2. Results of field work in
Costa Rica, 1955. Amer. Mus. Novitates, no. 1835, 32 pp., 13 figs.
Carr, Archie, and Larry H. Ogren
In Press. The ecology and migrations of sea turtles, 3. Dermochelys in Costa
Rica. Amer. Mus. Novitates, in press.
Manuscript. The ecology and migrations of sea turtles, 4. The green turtle
in the Caribbean Sea.
Deraniyagala, P. E. P.
1939. The Mexican loggerhead in Europe. Nature, vol. 144, p. 156.
Iarrisson, Tom
1954. The edible turtle (Chelonia mydas) in Borneo. 2. Copulation. Sara-
wak Mus. Jour., new ser., vol. 6, no. 4, pp. 126-128, pl. 20-21.
Leipper, Dale F.
1954. Physical oceanography of the Culf of Mexico. In Galtsoff, Paul S.,
coordinator. Gulf of Mexico. Its origin, waters, and marine life. U. S.
Fish and Wildlife Serv., Fish. Bull., no. 89, pp. 119-137, figs. 34-43.
Lewis, C. Bernard
1940. The Cayman Islands and marine turtle. Bull. Institute of Jamaica, sci.
scr., no. 2 (appendix), pp. 56-65.
Mast, S. 0.
1911. Behavior of the loggerhead turtle in depositing its eggs. Pap. Tortugas
Lab., Carnegie Inst. Washington, vol. 3, pp. 63-67.



SYNOPSIS: Tagging results and studies of unlaid eggs in dissected females
demonstrate that individuals of the Atlantic loggerhead sea turtle nest several
times on the same stretch of beach in a summer, but it is not yet known whether
each individual lays every year. Individual turtles can locate these places with
some precision. Tagging results show groups of turtles nest together several
times, and it is believed they stay together during the periods between the nest-
ing emergences.

Although fishermen, turtle poachers, and conservation officers
commonly believe that the Atlantic loggerhead sea turtle, Caretta
caretta caretta (Linnaeus), lays more than once during a season and
that groups of turtles remain together during the season to nest to-
gether, no detailed observations on these points appear to have been
made by biologists. Recent evidence of tagging studies proves mul-
tiple emergence and suggests group adherence of individuals. Fur.
their evidence that the eggs of a season are laid in two or more batches
has been the finding of unlaid eggs in discrete size groups in female
turtles dissected during the nesting season. Counts and measure-
ments of such eggs are included in the present paper.


In examining their tagging data on the green turtle, Chelonia
mydas mydas (Linnaeus), for possible evidence of group travel, Carr
and Giovannoli (1957: 9) found cases in which individuals that emerged
together tended to return to renest together later the same season.
We have clumped tag returns that suggest similar group movements
in nesting Caretta.

Field work supported in part by National Science Foundation Grants G-1684
and G-5479 (University of Florida, Principal Investigator Archie Carr) and by
the Georgia Game and Fish Commission. Contribution number 43 from the
United States Fish and Wildlife Service Bureau of Commercial Fisheries Biologi-
cal Laboratory, Brunswick, Georgia.
SFishery Research Biologist, United States Fish and Wildlife Service, Bureau
of Commercial Fisheries Biological Laboratory, Brunswick, Georgia.
7 Formerly Associate Professor of Zoology and Director of the University of
Georgia Marine Institute, Sapelo Island, Georgia. Present address: Department
of Meteorology, University of Wisconsin.


Our first evidence for grouped emergence resulted from limited
tagging studies conducted in 1957 at Hutchinson's Island near Fort
Pierce, Florida. While not so impressive as the results obtained at
Jekyll Island near Brunswick, Georgia, in 1958, to be described be-
low, they nevertheless suggest that group movements may be the
rule in loggerheads.
On 27 May 1957 seven nesting loggerheads were tagged on
Hutchinson's Island with monel cow-ear tags (Carr and Caldwell,
1956:3) fixed to the front flipper, including one numbered 78. On 28
May 1957, 11 turtles were tagged, including one numbered 23. Num-
ber 23 was released within 2 miles of the release point for number 78.
At 0115 hours on 30 June 1957, 34 days after the first tagging date,
Agent Robert S. Pfister of the Florida State Board of Conservation
found number 23 nesting "7 miles south of the Ft. Pierce Inlet," at
approximately the same place where she had been tagged. At 0120
hours only a short distance away, a few hundred yards at most, he
found number 78 nesting. In spite of the small size of the sample,
the fact that this double return involved two out of a group of only
18 turtles tagged makes it highly improbable that the dual recovery
was due to chance. This double return and a long-range recovery
in the northern Gulf of Mexico from the 27 May tagging (Caldwell,
Carr, and Ogren, 1959, herein) are the only reports to date from 72
turtles tagged on Hutchinson's Island during the 1957 season. This
lends significance to the dual recovery and enhances its value as
evidence of concurrent movements.


early June
(date uncertain) 5 9-11 July 4 22 July 1
6 June 6 11 July 5 23 July 1
10 June 4 15 July 6 24 July 2
13 June 7 16 July 7 25 July 3
9 July 4 17 July 6 29 July 1
10 July 1 18 July 6 31 July 3
Total 72

The results of the 1958 tagging studies on Jekyll Island clearly
show this phenomenon of group nesting emergence by loggerheads
(table 2). Eight turtles, numbers 125, G43, G47, G103, G105, G107,

Vol. 4


G108, and Gill, show such close agreement in their dates of first
and later emergences that they may be considered as one group.
Though our records are indefinite on the point, it is presumed that
all laid on the night of tagging or very shortly thereafter. This pre-
sumption is based on findings (presented below) that show a turtle
emerging and failing to nest one night will return the same or suc-


Tag Date First Second Third
Number' Tagged Return Return Return

110 June 6 (Id) July 10 (nd)
111 June 10 (dnl) June 16 (Id) July 5
114 June 10 (Id) July 23 (Id) July 29 (dnl)
117 June (?) (nd) July 18 (nd)
118 June 13 (dnl) June 28 (Id)
120 June (?) (nd) July 11 (nd)
121 June (?) (nd) July 10 (nd)
123 June 13 (dnl) July 29 (Id)
125 June 13 (dnl) July 16 (Id) August 1 (ld)
136 early June (nd) June 28 (ld) July 11 (ld)
144 June (?) (nd) July 26 (Id)
S375 July 11 (nd) July 14 (dnl) July 26 (dnl)
G30 July 10 (dnl) July 11 (ld)
G33 July 11 (dnl) July 23 (Id)
G37 July 11 (dnl) July 15 (nd)
G43 July 15 (dnl) July 28 (dnl) July 29 (dnl) July 30 (Id)
G47 July 16 (ld) July 31 (ld)
049 July 16 (dnl) July 17 (Id)
G102 July 16 (dnl) July 17 (dnl) July 18 (nd)
G103 July 17 (ld) July 30 (ld)
G105 July 17 (Id) July 30 (ld)
G107 July 17 (Id) July 31 (ld)
G108 July 17 (ld) July 30 (ld)
Gill July 18 (Id) July 31 (dnl) August 1 (Id)
G115 July 22 (dnl) July 23 (ld)
G119 July 25 (ld) August 7 (ld)

Tags bearing no letter prefix are marked for return to the University of
Florida; those bearing a "G" prefix are marked for return to the Georgia Game
and Fish Commission.
STurtle found dead on beach. Oviduct contained shelled eggs.
Turtle re-tagged when original tag pulled out during first recapture.



cessive nights until she nests successfully. Thus these turtles returned
together as a group to lay again after approximately 2 weeks.
As turtle 125 presumably laid in mid-June, her record suggests
that the group nested at least four times that summer, in mid-June,
in late June, in mid-July when most were tagged, and in early August.
The probability that the grouping shown by this series occurred by
chance alone, especially with so few turtles tagged, is so slight that
coincidence need not be considered. Possibly another aggregation on
Jekyll is the group made up of numbers 110, 120, 121, 147-G35, and
G30, but the data for this and possible other groupings are not con-
Aggregate nesting is also suggested by observations William W.
Anderson, United States Fish and Wildlife Service, made during a
shrimp study for the Service in Georgia from 1930 to 1938. The in-
vestigation involved considerable field work and afforded him the
opportunity to observe turtles from a small slow-moving boat. An-
derson noticed that during the nesting season turtles were not present
at all times in great numbers, but rather that they seemed to arrive
in the area in groups. Correlated was the general observation that
nesting turtles likewise tended to arrive together on the beach.
Later studies conducted at Jekyll Island by Caldwell and Berry
showed a similar phenomenon of groups of turtles on the beach at
one time, then periods with only an occasional individual present be-
fore another group appeared. Thus, while there was a general con-
gregating of turtles in the area during and just before the nesting
season, it appears likely that the turtles did not remain in the im-
mediate vicinity between nesting times, but perhaps moved elsewhere
to await their time for returning to renest.
Anderson further noted that at no time during the season were
turtles abundant in Georgia waters other than those immediately sur-
rounding the rookeries at Jekyll and Little Cumberland Islands. It
seems unlikely that the turtles return to their wintering grounds be-
tween nestings and regroup before returning for the next nesting ven-
ture. There remains for the loggerhead, as for the green turtle (Carr
and Giovannoli, 1957; Carr and Ogren, Ms.), the stubborn problem
of where they go in the interim. They may go offshore, but obser-
vations do not support this.

We referred earlier to a return to the Hutchinson's Island beach by
two turtles that had nested there about a month before. In the

Vol. 4


Atlantic green turtle the interval between the nesting ventures of a
season is 12 to 14 days (Carr and Giovannoli, 1957; Carr and Ogren,
Ms.). A similar interval was suggested for the loggerhead by Lewis
(1940: 62), which our recoveries at Jekyll Island corroborate. Pre-
sumably the recovery of the two turtles at Hutchinson's Island after
a month's absence must have been preceded by an unrecorded re-
turn 2 weeks earlier.


50 -K IT .I
50- TV



50- I


I 5 10 15 20 25 30 35 40 45
Figure 20.-Diameter-frequencies of freshly laid and ovarian eggs of the At-
lantic loggerhead turtle at Jekyll Island, Georgia, in 1957. Solid areas indicate
eggs actually measured. Dotted lines indicate estimated numbers of eggs within
the indicated ranges of diameters.

From the first week of June through the last week of July 1958,
72 loggerheads were tagged at the Jekyll Island rookery (Table 1).
Of these, 26 were recaptured-one or more times (Table 2). In addition
to these definite records, tourists reported seeing about 10 more
tagged turtles on the beach. As no data accompanied these reports
they are of no value in piecing out laying schedules.



From our observations, and from those on injury-marked turtles
made by others, we believe that a turtle interrupted in her nesting
will return either later that night or on successive nights until she
has fulfilled her mission. Carr and Giovannoli (1957: 24) reported
for green turtles a similar "singlemindedness of the nesting drive,"
borne out by turtles number 111, G30, G37, G49, 0115, and particu-
larly by G43 and G102 (Table 2).
Thus a turtle tagged on a given date but not known to have played
then, can be assumed to have laid within the following few days,
and any recovery of a turtle more than a week after the time of tag-
ging theoretically constitutes an example of second nesting (see, for
example, turtles number 118, 123, G33, G43, 147-G35 in Table 2).
In every case for which data are adequate, all the instances of
multiple nesting on Jekyll Island took place at intervals of 12 to 15
days, with the single exception of number 114. With the 2-week
interval between laying emergences shown so convincingly to be
standard, it can be presumed that the other tagged animals would
have shown comparable intervals had they been caught each time they
nested. For example, recoveries of turtles 117 and 144, like the
Florida returns noted above, probably represent second nesting
emergences after tagging. Turtle 123 may have returned a third
time. Turtle 136 definitely laid twice, and the interval between the
time of tagging and first corroborated laying is long enough to have
permitted a third nesting in the interim, or four nestings for the sea-
son. It seems likely that the turtles in the group discussed in the
section on Group Emergence laid four times.
Sapelo Island, Georgia, is not considered a "good turtle island,"
and is not part of the Jekyll rookery. The minimum straight-line dis-
tance between the north end of Jekyll and the south end of Sapelo is
approximately 19 miles. In 1958 three turtles were tagged on Sapelo
Island, one of which (G23) was recaptured there 31 July, two nights
after being tagged. She did not nest either time, but the return sup-
ports the popular assumption that each turtle nests on a single island,
and only on that island, even though concentrated nesting may be
going on at a nearby rookery. Another turtle, not tagged but hearing
distinctive marks, apparently laid twice on Sapelo, on 18 and 28 June.
The interval is short, but the evidence that the same turtle was in-
volved is convincing, and we believe this to be another instance of
multiple nesting on an island other than Jekyll. little Cumberland
Island, immediately south of Jekyll, seems from concentrations of
tracks seen from the air to be part of the Jekyll rookery, but there is

Vol. 4


no road to Little Cumberland, and no practical means were available
to visit the island at night to look for turtles tagged at Jekyll, or to
tag turtles for possible recovery at Jekyll.
Data extracted from a hitherto unpublished report (see Caldwell,
1959, herein) prepared in 1940 by William P. Baldwin, Jr. and John
M. Lofton, Jr. show similar results for loggerheads tagged on a rookery
at Cape Romain, South Carolina. These workers tagged 18 turtles
as they came ashore to nest. Turtle number 4 was tagged but did
not lay on 12 June; she was recaptured as she laid on 27 June. It
is assumed that she laid soon after the 12th, and the expected 2-week
interval between nesting ventures is indicated. Turtle number 13
was tagged but did not lay on 6 July. She was recaptured again
not laying on 28 July. The elapsed time clearly indicates attempts
at multiple nesting, perhaps three times in the 22 days. Turtle
10 was tagged on 3 July and recaptured on 4 July, nesting neither
time. Turtle number 4 returned to a point 1000 feet north of the
point of initial emergence; number 13, 950 feet southward; and num-
ber 10, 300 feet southward.
Unfortunately some of the people at Jekyll who furnished en-
thusiastic cooperation in tagging and in recording returns kept only
dates of tagging and return and did not record the exact spots in-
volved. It is of particular interest to note that in all cases where
exact data were available for tagging and return, the turtle involved
returned not only to Jekyll Island, but to the same portion of the
island, within 1/4 mile of the initial point of tagging on the 10.5-mile
beach. None of the many turtles tagged at Jekyll Island was found by
observers on Sapelo Island, nor were any of the few turtles tagged at
Sapelo recorded as nesting later at Jekyll. The only returns on each
island were turtles tagged on that island. Similar homing was noted
by Carr and Giovannoli (1957) and by IIendrickson (1958) for the
green turtle.

Data on egg size groups afford further evidence of multiple nest-
ing and corroborate the tag return data.
Early in the 1957 season an individual designated as turtle A
(Figure 20) that emerged on Jekyll Island 23 May was killed for study
before being allowed to nest. She contained 120 shelled eggs of
mature size (Carr, 1952: 391) she presumably would have laid that
night. In addition to the mature' eggs, a second group (II) of 182 eggs
consisted of large yellow yolks, and a third group (III) consisted of



about 25 much smaller yellow yolks. Eggs of size group IV were tiny
(4 mm. in diameter or less) white or yellowish spheres and occurred by
the thousands. These tiny eggs presumably serve as a reservoir and
may be present at all times in mature females. Since the 182 eggs
in group II were more than the expected complement for a single
laying, it was probable that some of the smaller ones in this group
and the larger ones in group IV would have gone to build up the
small group III to about the expected 125.
Another individual, designated as turtle B (Figure 20), was killed
in mid-season on 1 July, also on Jekyll Island, just after nesting. She
had deposited 144 eggs. The groups of smaller eggs in this individual
were better defined than those in turtle A. The mature eggs of both
turtles (group I in Figure 20) furnish definite evidence for one nesting
that season. Considering the two turtles A and B as one composite
animal, and postulating that nesting takes place at 2-week intervals,
it is reasonable to assume that a laying by this hypothetical single
turtle probably occurred between 23 May and 1 July. The group III
eggs in turtle A might well have reached mature size in the elapsed
month to become group I in turtle B. The fact that the nodes of
egg diameters of groups II and III of turtle B are further advanced
than corresponding ones in turtle A is further evidence that eggs
develop continuously during the season to replace laid clutches of
group I eggs.
While these data strongly suggested that multiple nesting occurs
in loggerheads, they did not furnish firm grounds for calculating the
number of times an individual might nest in a season, nor do the
tagging results. One female might not come to the rookery until
mid-season or later, and might nest only once or twice. Another
might nest very early and thus have time to complete three or more
additional layings. Turtle B in Figure 1, for example, might not have
nested in early summer, and her egg-groups II and III may forecast
two more nestings to take place late in the season. Or if she did nest
early, they may represent a third and fourth nesting for the season.
Conversely, her group III eggs might have been reabsorbed after the
1957 nesting season. Her group II eggs were large enough to have
been destined for laying in the 1957 season, and it does not seem likely
that any of her eggs of group IV would have reached maturity by
the end of the 1957 season. Possible evidence that reabsorption of
eggs occurs is the fact that some of the group III eggs in turtle B
were dark purple or black in color as if vascularized for reabsorption.

Vol. 4


In another instance turtle number G119 (Table 2) was killed after
laying the second time. She had deposited 90 eggs in a normal fashion.
Her oviducts contained 57 large yellow eggs approximately 14-30 mm.
in greatest diameter which could have forecast a third laying for the
season. There is no reason to believe she had not also laid 2 or more
weeks before she was tagged. In addition to the large yellow eggs,
she also contained about 200 whitish-yellow eggs 5-10 mm. in greatest
diameter, and several thousand eggs less than 5 mm. in diameter.
Still another possibility is that the individual might complete a
fixed number of nestings at 2-week intervals, no matter when she first
arrives at the rookery. Thus, one group of turtles may nest early in
the season (say 3 or 4 times during the first 6 weeks), another during
the middle 6 weeks, and a third group during the final 6 weeks. As
the laying season lasts only about 12 to 15 weeks, the groups of turtles
surely overlap in their periods of stay, which could account for the
larger number of turtles nesting in mid-season (see Caldwell, 1959,
herein). More than three groups of turtles, or one turtle nesting more
than three times, which our tagging studies suggest occurs, would
further complicate such a nesting regime, but not make it impossible.

We are indebted to a number of people who furthered our studies
by supplying information, physical aid, and encouragement. Some
of these to whom we owe special thanks are: William W. Anderson,
Carolyn Berry, Hugh M. Fields, Jack W. Gehringer, Evelyn Hellier,
Thomas R. Hellier, Jr., David Maxwell, Donald Moore, Clyde A.
Wilson, Jr., Melba C. Wilson, and Louis E. Vogele.
We are grateful for the cooperation afforded the project in Georgia
by the United States Navy (Naval Air Station, Glynco) in granting us
permission to make reconnaissance flights in their airships.
David Gould, Director of Coastal Fisheries for the Georgia Game
and Fish Commission, generously allowed us to take part in patrol
flights by the Commission airplane. We wish to thank the pilot,
Clifford C. King, for his cooperation in facilitating our observation
during the flights.
We are particularly indebted to Agents Robert Kilby and Robert
S. Pfister, respectively of the Georgia Game and Fish Commission
and the Florida State Board of Conservation, for their untiring co-
operation in the field. Officials of the two agencies were most helpful
in granting us collecting and study permits.


William W. Anderson furnished us with valuable unpublished
notes on Georgia sea turtles.
Seton H. Thompson and Richard T. Whiteleather of the United
States Fish and Wildlife Service Bureau of Commercial Fisheries,
and W. L. Towns and E. S. Jaycocks of the Bureau of Sport Fisheries
and Wildlife were especially helpful in making available the unpub-
lished reports of work done at Cape Romain, South Carolina.
For their critical examination of the manuscript we wish to thank
Mr. Anderson and Jack W. Gehringer.

Carr, Archie
1952. Handbook of Turtles. Ithaca, N. Y.: Comstock Publishing Associates,
xv + 542 pp., 37 figs., 82 pls., 23 maps.
Carr, Archie, and David K. Caldwell
1956. The ecology and migrations of sea turtles, 1. Results of field work in
Florida, 1955. Amer. Mus. Novitates, no. 1793, 23 pp., 4 figs.
Carr, Archie, and Leonard Giovannoli
1957. The ecology and migrations of sea turtles, 2. Results of field work in
Costa Rica, 1955. Amer. Mus. Novitates, no. 1835, 32 pp., 13 figs.
Carr, Archie, and Larry H. Ogren
Manuscript. The ecology and migrations of sea turtles, 4. The green turtle in
the Caribbean Sea.
Hendrickson, John R.
1958. The green sea turtle, Chelonia mydas (Linn.) in Malaya and Sarawak.
Proc. Zool. Soc. London, vol. 130, pt. 4, pp. 455-535, 15 figs., 10 pls.
Lewis, C. Bernard
1940. The Cayman Islands and marine turtle. Bull. Institute of Jamaica, sci.
ser., no. 2 (appendix), pp. 56-65.


Abridged and annotated by DAvm K. CALDWELL

FonEwoeD: After the first manuscript in the present series was finished and
submitted for publication, and after the field work for the second study was com-
pleted and the data partially processed, general inquiry revealed a manuscript
dealing with loggerheads, dated 1940, in the files of the Regional Office of the
United States Fish and Wildlife Service, Bureau of Sport Fisheries and Wildlife,
Atlanta, Georgia. This manuscript, resulting from Service-sponsored research
(then the Bureau of Biological Survey) by Service personnel, has been made
available for publication now through the efforts of Seton H. Thompson, Richard
T. Whiteleather, and William W. Anderson of the Bureau of Commercial Fish-
eries, and W. L. Towns and E. S. Jaycocks, of the Bureau of Sport Fisheries and
Although many of the findings presented in the 1940 report have been pub-
lished independently by subsequent workers (almost surely without knowledge
of the report), and although some of the topics are covered in the first two papers
in the present series, it was felt that so much of the material represents com-
pletely new data that judicious trimming would produce a valuable contribution-
one somewhat overlapping, but complementary, to work completed later. Be-
cause I was actively involved in field research on the loggerhead turtle and had
knowledge of its natural history, it was felt that among those Service personnel
interested I might be best qualified to develop the report into a publishable paper
that would not overly duplicate findings already or soon to be published.
It should be emphasized that all of the field work was done by William P.
Baldwin, Jr. and John P. Lofton, Jr., or by those they acknowledge, and that the
report which came to my hands is entirely theirs. I have deleted parts that are
repetitious with other studies, have added later literature citations and limited
data from my own findings where appropriate (so indicated), and have redrawn
those of their figures retained to conform with Bulletin style. In some instances
I have rewritten sentences for smoother continuity where parts were deleted.
For the most part the wording has been left as it was in their original report.
I hope that in no place have I changed Baldwin and Lofton's meaning. "We" or
"our" refer to Baldwin and Lofton. The 1940 manuscript has been returned
intact to the Bureau of Sport Fisheries and Wildlife Regional Office in Atlanta,
Georgia, where it is now on permanent file.
David K. Caldwell.
March. 1959

"Contribution number 44 from the United States Fish and Wildlife Service
Bureau of Commercial Fisheries Biological Laboratory, Brunswick, Georgia, and
a contribution from the United States Fish and Wildlife Service Bureau of Sport
Fisheries and Wildlife.


SYNOPSIS: Detailed field studies show that Atlantic loggerhead sea turtle,
Caretta caretta caretta (L.), make exploratory crawls to the beach during nesting
season, and the fact that a turtle is on the beach does not necessarily mean she
will nest at that spot, although she apparently will nest in the immediate vicinity
on the night she explores, or very shortly thereafter.
Evidence, contrary to popular beliefs, shows no correlation between nesting
activity and the stage of the moon, tide, and weather conditions. The physical
features of the beach are apparently the most important factors in determining
degree of nesting activity.
The nesting procedure in South Carolina is consistent with that noted in other
populations throughout the species' range.
Details of the nest and of the eggs, their incubation, and hatching are pre-
sented for future comparison with other species. An average period of incuba-
tion of 55 days is demonstrated in South Carolina, and a growth rate is given
for the embryos. Many hazards, such as numerous kinds of predators, roots of
vegetation, and unfavorable conditions of temperature and moisture are shown
to exist for the eggs and hatchlings, resulting in a high rate of mortality.
Considerable variation in size, color, and body fonn is demonstrated for
hatchling loggerheads.

Although South Carolina lies near the northern boundary of the
nesting range of the Atlantic loggerhead sea turtle, Caretta caretta
caretta (Linnaeus), the turtle nests abundantly there. This is especi-
ally true for the beaches of the Cape Romain Migratory Bird Refuge
(McClellanville, South Carolina) where over 600 nests are made each
season. This refuge, also a haven for bird colonies of many species,
consists of three low barrier islands and the acres of salt marsh (Spar-
tina alterniflora) which lie between them and the mainland. [Similar
conditions exist in Georgia at the Jekyll Island rookery discussed by
Caldwell, Carr, and Ogren, 1959, herein-D.K.C.]. The South Caro-
lina islands, known as Cape Island, Raccoon Key, and Bull's Island,
possess about 19 miles of ocean beach, most of which is potential
nesting ground for the loggerhead. Bull's Island is wooded but Cape
Island and Raccoon Key are not. The dune vegetation on all three
is very similar. The commonest plants that grow there are beach
oats (Uniola paniculata), cord grass (Spartina patens), and beach tea
(Croton punctatus).
As far as we can ascertain, the loggerhead nests on the Cape
Romain beaches in greater numbers than anywhere else on the Caro-
lina coast. Cape Island with 5 miles of front beach has 400 nests a
season; Raccoon Key with 8 miles has an estimated 200 nests; and
Bull's Island, about 6% miles long, has approximately 30 nests.

Vol. 4


For several years notes on the loggerhead have been kept by
personnel of the Cape Romain Refuge. In the summers of 1937 and
1938, under the direction of Andrew H. DuPre, Refuge Manager,
Lofton worked on the north end of the refuge, and in 1938 Baldwin
worked on the south end. During the summer of 1939 a more inten-
sive study of loggerhead nesting was conducted, the writers [Baldwin
and Lofton-D.K.C.] staying full time at Cape Island. Although
most of this report is based on our 1939 work, we have drawn from
the notes of our previous work, notes of Mr. DuPre, and from unpub-
lished information contributed by the Charleston Museum staff and
other local observers. Grateful acknowledgment is made to these
persons for their helpful suggestions and material.

[Baldwin and Lofton made measurements and recorded weights
of a few loggerheads at Cape Romain. The mean carapace length
for 18 turtles was 36/z inches, with a range of 334 to 40V2. These
results compare favorably with those made at Jekyll Island in 1958
and reported by Caldwell, Carr, and Ogren, (1959, herein). Baldwin
and Lofton found the following relationship between weight and car-
apace length: 33/4 inches in carapace length, weight 193 pounds; 353/4,
218; 36%, 262; and 39, 298. Another individual with a carapace of
approximately 35 inches weighed 257 pounds. Baldwin and Lofton
report a skull in the Charleston Museum (catalog number 2373) re-
portedly taken from a South Carolina loggerhead turtle that weighed
607 pounds. They also state that a McGowan Holmes of Edisto
Island, South Carolina, reported to the Charleston Museum in 1935
that the largest loggerhead of the many he had observed in that
section had a carapace measuring 48 by 38 inches.-D.K.C.]

In March the adult turtles appear in the bays and salt creeks which
wind through Romain's marshes in all directions. Although previously
they had been seen early in March, the first appearance recorded in
1939 was on 28 March. The first mating pair was observed in Cape
Romain harbor on 31 March. It is during April and May that the
turtles appear most frequently in the bays and creeks behind the
islands. During this time mating couples are seen commonly, and
often several males may be observed following or even clasping the


same female. The latest recorded mating in 1939 was on 11 May,
although it certainly was not the latest occurrence. In that summer,
egg-laying commenced in the middle of May. During June, July, and
August, when the adult females are laying on the front beaches, turtles
are not commonly seen in the creeks, and we have no records of
mating in those months. By October most of the adult turtles have
We have records of mating for every hour from dawn to dark.
Night mating doubtlessly occurs, hut we have no information on the
duration of copulation. As is the case with other species of marine
turtles, paired loggerheads may copulate for extended periods and
perhaps the females remate after each nest is made.
Mating turtles float in the water with the male in the superior
position. While the female is submerged completely, the highest
part of the male's carapace is usually out of the water. The head of
the male emerges for breathing every few minutes, and the female
struggles to the surface for air about every 5 minutes. With his plas-
tron on the female's carapace, the male holds immovably to her with
all four limbs, thus leaving the female free to swim. The very large
tail of the male, which is 8 inches or longer, bends down pressing the
cloacal opening against the similar organ of the female, and the two
are tightly joined.
Duration of Nesting
On Cape Romnain's beaches nests are made from mid-May to mid-
August. When work was begun at Cape Island on 19 May 1939 a
few nests had already been made. The last nest was made there on
the night of 18 August. Thus the laying season extended over a
period of 3 full months with its peak in June and July. [A similar sea-
son was found at Jekyll Island, Georgia-D.K.C.].

Nesting and Non-nesting Crawls
The crawling of the turtle on the beach does not necessarily sig-
nify that the animal has made a nest. If the site does not appear
favorable, the turtle often returns to the water without laying and
usually tries again farther down the beach. In our counts we differ-
entiated between nesting and non-nesting crawls. Each morning we
patrolled the entire 5 miles of beach and recorded the preceding

Vol. 4



0 0



20 30 5 15

25 5

15 25 5 15

Figure 21.-Nightly number of loggerhead turtle crawls with correlated tidal
and lunar conditions at Cape Remain, South Carolina, in 1939. The dates apply
to all sections of the figure. Section A represents the total number of nests made
each night (solid bars indicate total counts, open bars indicate that all crawls may
not have been recorded for that date); Section B represents the total number of
non-nesting exploratory crawls (bars as in A); Section C represents the phases of
the moon, with solid symbols indicating new moon and open circles full moon;
Section D represents the highest P. M. tides for the date; Section E represents the
time, to the closest hour, of high tide (+ represents A.M., a represents P.M.;
symbols above the dashed line represent dark hours, those below indicate day-
light hours).



night's nesting and non-nesting crawls. This information is presented
in Figure 21. Complete data for the first few days on the island are
not available and the information presented starts on 21 May. Except
for the nights indicated, the nightly number of crawls is complete;
those thus marked indicate that extremely high tides and blowing
sand may have obliterated some of the crawls before we reached them.
The greatest number of nests made on any night was 13, and the
nightly average for the 90-day period was 3.8. The greatest number
of non-nesting crawls made on any night was 31 and the average (90-
day) was 5.3. As is indicated in the figure, there is a fairly close cor-
relation between the nightly numbers of nesting and non-nesting

Correlation of Crawls with Lunar and Meterological Data
Also included in Figure 21 are the daily records of tidal and lunar
phases which would possibly affect nesting activities. These will be
discussed separately.
Moon phase. It is a common local belief that the greatest nest-
ing activity occurs during the period of the full moon. In Figure 21
the moon phases are diagrammed in relation to the number of crawls,
and we can find no correlation to justify this belief. The peaks of
egg-laying occur during all phases of the moon, and such peaks
appear to be about 10-13 days apart.
Monthly range of tide. Assuming that turtles can hold their eggs
for short periods, one might imagine that most turtles would put off
laying until that time of month when tides are highest. In this man-
ner they could utilize the higher water to float in nearer to the dunes.
As Figure 21 shows, however, there was no correlation between height
of tide and egg-laying. In that section the tides given are those
which occurred from 12 noon to 12 midnight and are projected tides
presented in the Coast and Geodetic Survey tables (1939).
Time of high tide. As loggerheads begin their nightly crawling
just at dark, one might assume that most turtles would lay on those
nights when the high tide, regardless of its height, was reaching its
peak just at dark. No such correlation was found.
In speaking of the Bermudian sea turtles in general, Babcock (1937)
mentions that they come ashore to deposit their eggs on a rising
tide. McAtee (1934), in writing of the loggerhead (apparently in
Georgia and other southeastern states), also mentions that the females
come ashore chiefly on the rising tide. At Cape Romain, however,
the loggerheads started coming ashore just after dark whether the

Vol. 4


tide was high or low, and most of the activity was in the first 4 or 5
hours after dusk. This information was gathered by nightly patrols
of certain stretches of beach and rechecked on the morning patrol.
Other factors. Although no barometric readings for the Cape
Remain area were available, comparison with Charleston data indi-
cated no correlation. The nesting of turtles was little affected by
minor storms or even easterly squalls. In one instance, however,
on the night of 10 July, a severe thunder storm which started just
after dark and was followed by an all-night rain may have been
responsible for the lack of turtle activity; no nests were made that
night and only one non-nesting crawl was observed, although there
was much activity on the preceding and following nights.
The highest daily air temperatures throughout the laying season
ranged between 810 F. and 970 F. The lowest daily temperatures
ranged between 66 and 79. There was no correlation between air
temperature and nesting activity. Likewise, there was no apparent
relationship between wind direction or velocity and turtle crawling.

Selection of Nesting Sites
The Cape Island beach during the summer of 1939 offered six
kinds of potential nesting sites to female turtles. Figure 22 shows
these beach types in cross section and we have given them descriptive
A. Truncate dunes: Sharply eroded dunes backing a beach 5 to
10 feet wide on an average high tide. Extremely high tides pounded
the base of these dunes. Turtles never were able to ascend the face
of these, although they often tried. The truncate dunes graded into
the next type.
B. Ledge section: A stretch of beach that had a V2- to 3-foot
ledge breaking the middle of its natural slope. This type was variable
and was formed by the action of wind and tide. At times the ledge
was high enough to prevent the turtles reaching the dunes to nest
[see Caldwell, Carr, and Hellier, 1956.--D.K.C.].
C. Wide sloping beach: 25 to 40 feet wide from average high
tide line to base of dune. The outer dune was a continuous ridge
which paralleled the ocean front and was broken in only a few places.
Turtles could easily crawl from the surf to the base of the dunes.
D. Narrow flat beach: 10 to 20 feet wide and backed by small
separated dunes. Turtles could often climb these dunes or go through
the gaps between them.



E. Wide flat beach: Similar to the narrow flat beach, 30 to 50
feet wide and backed by small isolated dunes.
F. Barren areas: Stretching 100 to 400 feet back from the crest
of the beach, with only traces of vegetation or low dunes to break
their flatness.




JI*- 3iL 0



Figure 22.-Diagramatic cross sections of beach types at Cape Island, South
Carolina, in 1939. See text for details.


The Cape Island beach, in general, is much narrower and steeper
than those of Raccoon Key and Bull's Island, and the sand is coarser.
The beach at Cape Island is by no means stable, but is constantly
cutting away and building up. Remains of nests made in 1938 were
noticed in 1939 to be on top of truncate dunes 15 feet high, which in-
dicated considerable cutting away during the winter between these
two nesting seasons. Observations in the first part of the summer of
1940 show that the beaches have changed again. In fact, the truncate
dunes of 1939 have been changed into a wide sloping beach of 1940
by the deposition of sand at their base so this stretch of beach which
was so unsuited for turtle nesting in 1939 is an ideal type in 1940,
and contains an abundance of crawls.
Just as certain types of beach appeared to our eyes more favorable
than others for nesting, so did they to the turtles. Data to substanti-
ate this, based on the location of 343 nests and 463 non-nesting crawls,
are offered in Table 3.
Some of the most interesting facts that can be deduced from the
information presented in Table 3 are those relating to turtle behavior
in selection of nest sites. What process of thinking makes a turtle
leave the truncate dunes without nesting and swim farther along
the shore to nest on the wide sloping beach? Such things happened.
In the truncate dunes one nest was made every 197 feet of ocean
front and one non-nesting crawl every 32 feet; for every turtle that
laid on this low beach, six turtles returned to the surf without laying.
On the high wide sloping beach, however, turtles made one nest
every 28 feet, and one non-nesting crawl every 55 feet. For every
turtle that nested, a theoretical half of a turtle returned without nest-
ing. Thus this high type of beach backed by rounded dunes (see
Figure 22) was chosen by turtles more often than any other type.
With its 1 nest every 28 feet, compare it to the barren area with its
one nest every 204 feet. This is further evidence that low dunes
backing a high beach increase its desirability as a nesting site.
Other factors, such as the amount of moonlight, probably influence
the turtles in selecting various types of beach, but to what extent we
do not know. Statistical data, which will not be presented here,
indicated that throughout the season there was no important shifting
of turtle nesting from one type of beach to another. [Aerial reconnais-
sances of all of the beaches of Georgia and most of those of North
Carolina, South Carolina, and the Atlantic coast of Florida have
indicated that nesting turtles show a preference for a beach backed
by high dunes or vegetation, which thus presents a dark and broken





Truncate Dunes

Ledge Section

Wide Sloping

Narrow Flat

Wide Flat




Ratio of
' Number of Number Number of Number of feet nesting


feet of
beach per

of non- feet of beach
nesting per non-
crawls nesting crawl

of beach per
both types of


10 197

50.0 14071


69 204


crawls to

1 to 6.1
1 to 1.5

1 to 0.5

1 to 1.1

1 to 0.6

1 to 2.7


1 to 1.4

__ __ __ -


horizon to a turtle in the water instead of the lighter and relatively
unbroken outline offered by sand flats or the open ocean. This may
be one factor in drawing the turtles to such beaches. To turn sea-
ward or along the shore to the light, unbroken, horizon would of
course be disadvantageous to a turtle trying to land to nest. The
apparent hesistancy for a turtle to strand on a barren flat may be a
secondary result of this same phenomenon of relation to horizon,
rather than some physical factor of the barren beach itself.
In an analysis of distance crawled by nesting and non-nesting
females in relation to the type of beach, Baldwin and Lofton found
that the turtles prefer to nest on high beaches near or in the dunes,
beyond the reach of the tide. In addition, on large barren sand flats
where turtles may crawl hundreds of feet back from the ocean, they
prefer to lay only 1 to 30 feet from the crest. They found that adult
turtles crawling far back on these barrens often became confused
and wandered hundreds of feet in all directions before locating and
reentering the ocean. Therefore, nesting close to the ocean not only
guarantees a safer journey for the young when they hatch, but also
insures the adults' safe return to the surf.-D.K.C.]

Primary Excavation
When the turtle finally has selected a desirable nesting place,
she makes a primary excavation. This is a shallow depression, larger
than or approximating the size of the turtle, made by the turtle's move-
ments. The turtle moves the posterior end of its body from side to
side and pushes the sand out with its hind flippers, often making the
middle of the excavation a foot deep. This primary excavation is
largely exploratory, and often the turtle will move on farther and
dig again if the site does not suit her. Turtles made this primary
excavation in 23 percent of their non-nesting crawls; in the best type
of nesting site, the wide sloping beach, it was made in 46 percent of
the non-nesting crawls. In the truncate dunes, one of the least de-
sirable sites, it was made in 13 percent. In short, those beach types
that had the most nests per unit of ocean front likewise had the most
investigation, as indicated by primary excavations by non-nesting
turtles. Several factors are responsible for the abandoning of these
primary depressions. An obvious one had to do with the conditions
affecting digging, namely: sand packed too hard, sand too dry and soft,
layers of oyster shells, and an abundance of tough vegetation roots.
Another factor was position in relation to tide, for sites well above
the average tide level are preferred. [It is presumed, though not


stated, that all nesting females made the primary excavation as was
the case during 1957-58 studies on the Jekyll Island rookery.-D.K.C.]

Secondary Excavation
[Here Baldwin and Lofton cite the work of others as being repre-
sentative of their own findings. An illustrated description of the
process is presented by Caldwell, Carr, and Ogren, (1959, herein).
One comment by Baldwin and Lofton, also noted on several occa-
sions at Jekyll Island in 1958, concerns repeated secondary digging
by a turtle. They state that just as the hardness or the caving in
of the sand or the presence of vegetation roots affect the primary
excavation, so do they often cause the turtles to cease digging the
egg hole. In one site examined, the female had dug eight holes
and still had not laid her eggs.-D.K.C.]

Laying and Covering the Eggs
[This process, while described by Baldwin and Lofton, has been
discussed in detail and illustrated by Caldwell, Carr, and Ogren
(1959, herein).-D.K.C.]
Return to the Sea
After covering the nest, the turtle is ready to return to the sea.
Of the 350 nest sites examined, in only one instance did we find that
a turtle had paused on the return crawl to make excavations similar to
those normally made before digging the egg hole. In returning to
the sea the female is somewhat exhausted and usually makes frequent
stops to rest. One turtle that had not been disturbed crawled the
180 feet to the sea in 25 minutes. Another undisturbed turtle traveled
the 50 feet to the surf in 3 minutes. The strength of these turtles is
illustrated by the fact that one which had just finished laying carried
two of us to the ocean on her back-a weight of about 275 pounds.
Not infrequently turtles nesting at Cape Remain became lost on
the return to the sea. This occurred on two types of beaches, flat
barren areas and those backed by isolated dunes. These barren
areas, from 200 to 400 feet across, gradually slope back from the crest
of the ocean beach making the ocean invisible to a turtle 50 or 60
feet inland. One turtle, after making four primary excavations, moved
inland, became lost, and wandered extensively for 2,140 feet over
the sandy flat. Another turtle, also on a barren area, apparently made
several small circles after nesting to determine her position with
respect to the sea before she returned to the water. A third indi-

Vol. 4


vidual nested well back from the crest of the beach in the barren
area, and on completing her nest crawled diagonally back to the crest
of the beach to a point where she could see the beach. For some
undetermined reason she then reversed her direction and crawled for
several hundred more feet around the barren area before returning
to the water. Such action was most unusual. A fourth turtle became
confused among a group of isolated dunes. She nested on the top
of a 10-foot dune 100 feet from the ocean. Upon descending the
dune, she could not see the ocean and wandered extensively among
the 2- to 5-foot dunes, never climbing any of them, until eventually
she reached the safety of the ocean beach. An occasional loggerhead
skeleton far back among the dunes is mute evidence that turtles do
remain lost until the merciless heat of the rising sun kills them.


Position of the Egg Deposit
When the laying turtle has returned to the sea, its tracks lead to
a nest site that is easily recognized by the churned up sand and crushed
vegetation. This area, if located in dune vegetation which hampers
the movements of the turtle, is usually circular and 4 or 5 feet in di-
ameter. In sites lacking plant growth, the muddled areas are oval
to oblong, and may reach a size of 6 by 25 feet. The exact position
of the nest in all this muddling may appear difficult to locate, but with
a little practice one can soon pick out the exact spot. To us it ap-
peared that the egg deposit was usually near the fore, or entrance,
edge of the muddling and equidistant from either side.

Depth of Eggs
The cavity the eggs fill is 6 to 10 inches deep, 8 to 10 inches
wide, and slightly wider at the bottom than at the top. This egg
deposit is found at varying depths. The depth of the top eggs in
317 nests ranged from 5 to 22 inches, with two-thirds of them between
the 11- and 16-inch levels. This agrees with the depths of six North
Carolina nests measured by Coker (1906). As already mentioned,
fresh nest sites in open sand present a different appearance from those
in dune vegetation, and it was thought that the depth of the egg
deposits might correspondingly be affected. Distribution of the data
according to the various degrees of cover, however, revealed only a
slight tendency for nests in the dune vegetation to be a bit shallower
than those on the edge of vegetation or on open beaches. The ex-


treme depths were reached only by turtles making unusually deep
primary excavations, and egg holes as deep as possible, with the
eggs covered by sand to an extraordinary height. In conclusion it
might be mentioned that the egg deposits laid at the last of the sea-
son were buried just as deeply as those first laid. Furthermore, there
was no apparent correlation between the depth of the eggs and the
chances of sand crab depredation (see below).

Sand Conditions
The sand piled over the fresh egg deposits is usually reduced
1 to 2 inches during the incubation period by wind and tide action.
Obviously this erosion and subsequent obliteration of the site de-
creases the chances of nest depredation.
The sand over the nest, as left by the turtle, is firmly packed im-
mediately above the eggs and loosely piled above that. As incubation
proceeds and the eggs settle, an air space often forms between this
packed sand and the top eggs. Many times, by the time the young
turtles have hatched, this space has grown to be a small domed cham-
ber. If the arch of this chamber collapses and the sand falls upon the
eggs or young, a small but noticeable surface crater results. This
probably is easily found by foraging sand crabs [or raccoons-D.K.C.]
to the detriment of the nest.

Number Laid
A study of 71 nests throughout the laying season' revealed clutch
sizes ranging from 64 to 198 eggs, with an average of 126.
Six nests examined by Coker (1906) in North Carolina contained
118 to 152 eggs. Alexander Sprunt, Jr. has checked the number of
eggs in loggerhead nests for many years in the Charleston section.
His three highest counts were 180, 219 (Raccoon Key), and 341 (Sulli-
van's Island). Marshall Alston, a negro fisherman who formerly col-
lected and sold the eggs from hundreds of Cape Romain nests, re-
ported that the smallest clutch he ever found contained 65 eggs and
the largest 280.

Relation Between Number and Time of Season
Several authors have pointed out that it was "believed" that the
loggerhead laid several clutches a season, the number of eggs per
clutch decreasing each successive time. [It has now been shown
(Caldwell, Berry, Carr, and Ragotzkie, 1959, herein) that individual

Vol. 4


loggerheads do nest several times a summer.-D.K.C.] We have
analyzed the clutch size for 71 Cape Remain nests according to the
time of season laid. It appears that the number of eggs does de-
crease as the season progresses. [A similar analysis of 26 clutches
at the Jekyll Island rookery in 1958 produced the same results.-
Size of Eggs
The measurement of 827 eggs taken from 44 nests the day after
they were laid revealed that the greatest diameter of normal eggs
ranged from 35 to 49 mm., with an average of 41.5 mm. Loggerhead
eggs, when laid, appear perfectly round. Many of the measurements
were secured by measuring only the 5 top eggs in each nest. This
sampling avoided handling of whole clutches and the subsequent
effect on percentage of hatch. Some nests were completely excavated
and the entire clutch measured and weighed. The total weight of
119 eggs in one nest was 4,155 grams, or an average weight of 35
grams per egg. The variation of egg diameter within a clutch ranged
from 3 to 11 mm.

Size of Eggs in Relation to Order Laid
Further investigation of egg size variation revealed that, within
the clutch, the eggs laid last were smaller than those laid first. This
was determined by the measurement of six freshly-laid clutches. The
resulting data are presented in Table 4. The eggs were measured
as they were removed from the nest and each group of 20 is com-
posed of eggs deposited in the same layers and within the space of a
few minutes or, in short, in the order that they left the female's body.
The groups of 20 are arranged in the table with the eggs found in
the top of the nest (laid last) at the top of the column, and in de-
scending order through the nest to those in the bottom (laid first).
That the eggs laid last would be smaller than those laid first seems
natural if one considers their relative position to the many undevel-
oped eggs that remain in the turtle's egg tubes. All these measure-
ments were made the morning after each nest was made and the
possibility of nest pressure affecting these diameters may be largely
disregarded for the eggs were in no way misshapen. Moreover the
range of variation within each layer was additional evidence that
the size differential was natural.
Eggs of unusual sizes are occasionally found in nests. Small yolk-
less eggs 28 to 30 mm. in diameter are one type and may represent


the last eggs laid by a turtle. On the other extreme, abnormally large
eggs are occasionally found. One egg, almost hen-egg shaped, meas-
ured 51 by 43 mm. when laid. Another, with two yolks, measured
66 by 47 mm.

Relative position
of eggs in nest

20 laid last
(top of nest)

Nest Numbers
294 295 322 331 337 346

39.8 37.7 40.4 41.4 45.1 43.8

40.6 38.4 40.6 42.6 45.7 44.3

41.2 38.8 40.7 42.7 45.9 43.9

42.3 39.2 40.7 42.7 45.4 43.9

43.6 39.4 40.7 43.1


20 laid first
(bottom of nest)

Average diameter

40.2 40.9 -

38.9 40.7 42.5 45.5 43.9

Egg Size in Relation to Adult Size

A definite correlation between the size of the eggs laid and the
size of the turtle was noticed. In seven instances in which the cara-
pace lengths of the adult turtles and the average diameters of their
eggs were known, it was found that the larger the turtle, the smaller
the average size of her eggs.


Development of the Embryo

From embryo measurements secured through periodic examina-
tion of two nests, a composite growth curve has been constructed
(Figure 23). Macroscopic examination of opened eggs revealed no
embryos for the first 2 weeks, but on the 14th day embryos about one
millimeter long were observed in several eggs. From then on growth

Vol. 4


was rapid. When examined on the 26th day the embryos were pale
grayish blue and showed movement, and by the 32nd day they were
very active and their eyes were open. Fifty-four days elapsed be-
tween the night of egg-laying and the appearance of the turtles on


70 -



40 U-

20 -

I .

10 V

/ *-

0 ,I I I
10 20 30 40 50 60


Figure 23.-Composite growth of loggerhead turtle embryos from two nests
at Cape Island, South Carolina, in 1939. Dashed line represents total length,
solid line represents carapace length, dotted line represents carapace width. The
average diameter of the five top eggs when laid in each nest was 41 mm.


the beach. Hatched and developed turtles, however, were down in
the egg deposit on the 51st day and perhaps earlier.
During incubation one of the most obvious external changes that
occurs is the "whitening" of the egg shells. When deposited, the
creamy white eggs are bathed in a clear secretion which causes them
to glisten. This soon evaporates and the shells gradually whiten.
Several nests made in August were examined periodically and it
was found that on the second day of incubation the majority of the
eggs throughout the deposit had small round white marks on their
"tops", with a few eggs having them on the sides, and none on the
under surface. By the end of the first week of incubation the whiten-
ing of each shell was three-fourths to nine-tenths complete, and was
proceeding at the same rate for all depths of the egg deposit. At
this stage the small remaining unwhitened areas were all on the under
surfaces of the eggs. By the end of the second week the shells were
completely white, and this probably had occurred about the 10th
or 12th day. This drying and hardening of the egg shell, which pro-
ceeds uniformly regardless of the location in the egg deposit, points
to a uniform heat distribution and incubation rate throughout the
nest. The shells of infertile eggs do not whiten in this manner, but
by the end of several weeks have acquired a deep creamy color.
Another obvious change is the gradual swelling of fertile eggs as
incubation proceeds. The absorption of soil moisture is responsible
for this. The total length of the fully developed embryo just before
hatching is greater than the largest diameter of the freshly laid egg.

Incubation Time
The length of incubation was considered to be that period begin-
ning with the egg laying and ending with the appearance on the sur-
face of the main group of young turtles. For 55 Cape Island nests
this ranged from 49 to 62 days, and the average period was 55 days.
[Caldwell, Carr, and Hellier (1956) found incubation periods in Florida
as long as 68 days under somewhat unnatural conditions of handling
and habitat-D.K.C.]

Factors Affecting Incubation
Some half dozen factors might be considered as possibly affecting
the incubation length: Sunlight and shade, nest temperature, depth
of egg deposit, soil type, moisture content of the soil, and tidal and
underground water level conditions.

Vol. 4


Sunlight and shade. Incubation periods of nests made at the first
of the laying season (last of May) and those made at the last of that
season (last of July) were found to be longer than those for nests made
in the middle of the season. This, it was felt, was due to the total
amount of heat received by these nests. This heat factor depended
upon possible hours of sunlight, the actual hours of sunlight, and the
range of air temperature. Data for the Charleston area supplied by
the U. S. Weather Bureau indicate that the possible hours of sunlight
at the start of the laying season (middle of May) was 14 hours per
day, rising to 14.3 through June, and gradually dropping to 12 hours
by the end of September (practically the incubation season). The
actual hours of sunlight, however, were much lower than the possible
hours: 64 percent in May, 60 percent in June, 75 percent in July, 61
percent in August, and 57 percent in September. The average daily
air temperature was closely correlated with the actual hours of sun-
light, those periods experiencing the most sunlight also having the
highest temperatures. The temperatures through the last of June,
July, and first of August averaged higher than those at the first and
last of the incubation. In short, incubation periods shortened as the
temperature and amount of sunlight increased.
Additional information on the relation of incubation length to the
amount of sunlight is supplied by the following observation by Mr.
Chamberlain of the Charleston Museum. He collected 12 eggs from
a nest made on Cape Island on 6 June 1927. Placed in a box of sand,
these eggs were kept in a warm garage and occasionally sprinkled
with water for 2 weeks. They were then removed to a location where
they received 2 hours of sunlight daily. On 16 September, 102 days
later, the eggs were uncovered and it was found that, of the two
hatched turtles, one was still alive and of normal dimensions. This
extreme length of incubation caused by unnatural conditions was
no doubt largely due to the absence of sufficient sun heat.
Under natural conditions shading is caused by dunes and thick
vegetation. In analyzing the incubation lengths of specific nests in
relation to natural conditions of sun exposure, tide, and depth of egg
deposit, it was found that for the most part the data further illustrated
that the incubation period varies with the amount of sun heat.
Nest temperature. As determined by a fairly extensive series of
thermometer readings taken under all conditions of weather, the tem-
perature within the nest is subject to less fluctuation than the surface
temperature. Thus, while our extremes of daytime surface tempera-
tures ranged from 740 to 1280 F., the temperature within the egg


deposit fluctuated only from 770 to 93 F. In fact, the egg deposit
temperature usually remained between 82" and 88, and the 770 read-
ing was recorded only after a 3-day rain. The constancy of tempera-
ture within the nest was maintained not only during the day but also
at night, even though the surface temperature might then fall con-
siderably. The maintenance of a stable temperature appears to be a
requirement for a normal incubation length. Of course the tempera-
ture decreases with an increase in the depth at which readings are
taken, but in the normal depth range of loggerhead nests this is a
matter of only 1 or 2 degrees.
Depth of eggs. It will be recalled that at Cape Island there was
considerable range of depth for eggs in different nests. To determine
whether the depth of eggs affected the incubation length, one fresh
nest was excavated and groups of eggs from all parts of the original
deposit were reburied at varying depths under similar environmental
conditions. On the 55th day of incubation the young were out of
the eggs in all the levels from 12 to 30 inches. From the relative
position of the young it may be assumed that those in the shallower
depths hatched slightly before those in the greatest depths. Twenty-
four hours later they had reached the surface from the shallowest
deposits, but from the extreme depth they did not reach the surface
until 8 days later. Therefore the depth does not greatly affect the
actual length of incubation, but only the time required for emergence.
It is of additional interest to point out that the young from the 12
smallest eggs in this clutch, which were buried together at the 15-
inch level, were on the surface on the 54th day, or 2 days before the
young from average-sized eggs at the 15-inch level had reached the
surface. This may indicate that small eggs hatch before large eggs
of the same clutch.
Soil type and moisture content. Two closely related factors that
doubtless affect incubation are the soil type and moisture content.
On the Cape Island beach the soil types varied from crushed oyster
shell to fine sand. The latter is usually very dry. Three types of sand
were assayed for moisture content. These samples, taken from below
the surface, were typical of the majority of nest sites. The moisture
contents were determined by Dr. Horatio Hughes of the Department
of Chemistry of the College of Charleston, and are presented below:
1. Fine sand at the base of dunes in Uniola panic-
ulata roots ...- --- -- ---- 1.3%
2. Beach sand at the base of truncate dunes ---... 3.1%

Vul. 4


3. Coarse sand from barren flats among isolated
dunes -- 4.2%

The above figures are the percentages of moisture by weight.
Sand taken from the site of one North Carolina nest by Coker (1906)
contained 8.8% water.
Underground water level and tide. Although the layer of sand on
the surface is dry as a result of evaporation, the sand a few inches
below is damp, and this condition extends down to the underground
water level. To the touch this sand is moist and cool when compared
with that at the surface. On top of the dunes the upper layer of dry
sand appears to be thicker than at the base of the dunes or on flats.
In all of the above sites loggerhead nests experience normal incu-
bation, and it appears that the optimum moisture content would be
2 or 8 percent. In nests in low areas where the tide not only can
cover the nests frequently but also raise the underground water level
around the eggs, the incubation period is lengthened. In one Bull's
Island nest so situated in 1938, the sand was so wet that earthworms
(Lumbricus) were found in the deposit, and the incubation period,
as based on the only turtle that hatched, was 80 days. The effect of
water on the percentage of hatch will be discussed later.

Escape from the Egg
As the end of the incubation period nears, the eggs have increased
considerably in size through the absorption of water. The curved
embryo, which completely fills the egg, develops a sharp point on the
snout just before hatching. The combination of the increased internal
pressure and the use of the egg tooth facilitates the escape from the
egg shell. The pipping and escape from the eggs occur in all levels
of the egg deposit almost simultaneously. In one nest we examined
the turtles were just pipping the eggs on the 48th day of incubation;
they had egg sacs measuring /4-inch by 1 inch, and their carapaces
did not appear to be fully grown. On the 55th day the fully de-
veloped young, without trace of the egg sac, appeared on the surface
of the beach. The shortest period of actual incubation we recorded
was one in which the young were pipping the eggs on the 45th day.
In general, the external egg sac has been completely absorbed shortly
after the young have escaped from the eggs, although it may occur
before this act has been completed.



Escape from the Nest
Internal egg yolk must nourish the small turtles during their up-
ward struggle through the sand; while this climb of 1 to 2 feet may
take only 1 day, the average time is 2 to 3 days, and not uncommonly
as long as 5 or 6 days.
Young loggerheads usually appear on the surface at night, which
prevents their being killed by the heat of the daytime sun. The in-
tensity of heat is probably the factor controlling the time of this egress,
for turtles found 1 to 4 inches under the surface in the middle of the
day were inactive, but emerged in the cool of the following night.
In the few instances where turtles reached the surface during the
day they appeared stupified by the surface heat which soon kills
them. Turtles removed from the depths of a nest during the day,
however, and released on the beach easily reach the water before
being affected.
Just as the turtles escape from the eggs more or less together
throughout the nest, most of them arrive at the surface during the
same night. Those climbing up first loosen the sand and make the
way easier for the last of the hatch. Sometimes the escape from the
nest will last a week, with the main emergence preceded or followed
by successively smaller numbers.

Percentage of Hatch
The percentage of hatch, based on 62 nests, is presented in Table
5. The nests are divided into groups according to relation to tide
exposure and presence of vegetation roots. Not only are the aver-
ages presented, but also the range of hatchability for each type. The
range indicates that some nests will be highly unsuccessful no matter
how favorable their location. The average hatch was 73.4 percent.
Eggs that did not hatch were opened and examined macroscopically;
some of those considered as having no development may well have
contained extremely small dead embryos. As Table 3 shows, however,
20.7 percent of all eggs were infertile, and 3.8 percent contained
embryos that died in various stages of development. One interesting
discovery was that 5.3 percent of the eggs laid among Uniola panicu-
lata were destroyed by its roots. The hair roots formed thick mats
around the individual eggs, eroded the shells, and desiccated them;
often the sharp-pointed stolons pierced the eggs. A small number
of the turtles that pipped their eggs were unable to completely escape
the shell and died. Still another small percentage escaped from the

Vol. 4



Open, Exposed Sites

covered by


Mean: 66.9
Range: 29.0-97.0

Embryos died Mean:
in eggs Range:

No apparent

Eggs destroyed
by Uniola

Young died
in pipped eggs

Young died
in nest










Never covered







Base of Dunes

Occasionally Never covered
covered by by
tide tide













On Dunes
Uniola roo

Never cover







19 4 14

ts Average









Total nests 13


shell successfully but were caught in the nest and died. This was
caused by their inability to climb through the tightly packed deposit
of hatched eggs or matted vegetation roots, or their tendency to bur-
row horizontally into hard sand instead of perpendicularly to the
surface. In summing up the data this table presents, it may be said
that those nests located at the base of dunes and rarely if ever covered
by water are better situated than those on exposed beaches, especially
those occasionally covered by tides, or on the vegetated dunes. As
noted earlier in this paper, the female loggerheads selected sites at
the base of dunes much more than in the other types.

Size of the Young
A total of 398 young loggerheads from 31 nests were measured
just after hatching. The carapace length ranged from 38 to 50 mm.,
with a mean of 45 mm.; the carapace width ranged from 31 mm.
to 40 mm., with a mean of 35.5 mum.
The average weight of a newly hatched turtle, as determined
from 104 specimens of one nest, is 21.2 grams. [These turtles are
heavier than those reported by Caldwell, Carr, and Hellier (1956)
from two localities in Florida-D.K.C.]
It was mentioned earlier in this paper that the larger turtles laid
the smaller eggs, but whether a relationship exists between the size
of the adult and young is not known.

Color of the Young
Newly hatched loggerheads have a wide range of color. The car-
apace varies from a yellowish buff through all shades of brown to
a gray black. This coloration is by no means uniform, but lighter
on the outer plates of the carapace. The plastron ranges from a
pure creamy white to a gray black mottled with this white. Prom-
inent points on the plastron are lighter than the grooved or flat areas.
A light plastron is not necessarily correlated with a light carapace.
Sometimes the individuals from a single nest have plastrons predom-
inantly light or dark. These colors refer to those of wet specimens,
for most dry specimens have a grayish cast.

Shield Variations
We examined 154 specimens from Cape Romain nests for varia-
tion in the number of costal shields [lateral laminae-D.K.C.], infra-

Vol. 4


marginals, extra anals, and extra gulars-one pair of each of the latter
two is the expected number. The results of this analysis are included
as Table 6. Although not evident from the table, the young of some
nests tended to have greater shield variation than those of others.



Right Left

of Total

Number ot Turtles

Lateral laniinde





Extra (more than one pair) anals

None 114
Median 13
Right & Left 5
Right, Left & Median 2

Extra (more than one pair) gulars

Right & Left

Abnormal Young

During this investigation a few specimens were found which
might be termed freaks. One turtle that hatched and was otherwise


normal had no external openings for the eyes. Another had no left
front flipper. One pair of embryos was found attached to the same
egg yolk, and although completely developed, the turtles were dead.
In another instance an embryo having one head joined to two bodies
also died before hatching. An unusually small turtle that hatched and
was otherwise normal had a carapace measuring only 34 mm. by 25
mm. (expected measurements arc 45 mm. by 35 mm.).
The most interesting abnormality, however, was the presence of
white embryos in about 15 percent of 65 nests examined. Never
more than 3 or 4 were found in one nest. These embryos, in all stages
of development, ranged from blueish white in the younger forms
to creamy white in the fully developed ones. The carapace, plastron,
and skin of the animals were uniformly colored. None of these ab-
normal embryos hatched, but some were found fully developed and
alive in the egg a week or more after the normal turtles of the nest
had hatched. One was found that had pipped the egg and then
died. This probably indicates that development of the white embryos
requires a longer period than normal ones. In addition, this absence
of color appeared to be linked with the presence of malformations of
the jaws and eyes.
Enemies of Adults
Enemies of the loggerhead are numerous. Formerly many of the
adults were slaughtered for food in this region, although the practice
is now outlawed by South Carolina. Some references indicate that
sharks also destroy the adults. We have a local record of dogs killing
loggerheads. According to a note in the Charleston Museum files,
T. B. Fitzsimmons found two dead turtles with torn necks on the
Botany Bay Beach, Edisto Island, within a few days of each other
in the summer of 1929. A few nights later he saw his two hound
dogs rush down to the beach and attack an adult turtle. He stopped
the dogs and found the same wounds as on the other two turtles.

Enemies of the Young
The young are subject to tremendous predation by fishes, sharks,
sand crabs (Ocypode albicans), raccoons, gulls, and to a lesser extent
by crows. Sand crabs, which cover the beaches at night, form a
gauntlet that the hatchling turtles must run, and many of the de-
fenseless loggerheads never reach the sea. While the larger crabs

Vol. 4


Hatched Successfully

Entered by crabs

Destroyed by raccoons

Washed away

Total number of nests

One nest per









Sloping Narrow Wide
Ledge Beach Beach Beach Barren


Total Average
Nests Percent

197 feet 56 feet 28 feet 40 feet 78 feet 204 feet 82 feet


can easily carry the young turtles to their burrows and consume them,
medium-sized crabs often have difficulty holding the struggling prey.
On 14 September 1931 according to a note in the Charleston
Museum files, a young loggerhead was taken from the stomach of a
"black-fish" (Centropristes striatus) and identified by E. B. Chamber-
lain. This fish was taken in 14 fathoms on "South Ground" off the
Charleston bar. Interesting not only in its connection with predation,
this also points to a possible migration of the newly hatched turtles
to deep water. [See Caldwell, Carr, and Ogren (1959, herein)-
Enemies of Eggs
Depredation of nests is very high in all parts of the loggerhead's
range. McAtee (1934) says that nests of the loggerhead are pilfered
by various enemies, but that the work of natural enemies is insignifi-
cant compared to the depredations of hogs, where they are present,
and of man. At Cape Romain neither of these two predators is pres-
ent, but depredations by sand crabs and raccoons are extensive. Table
7 presents the fate of 343 Cape Island nests. The data are tabulated
for beach types and for the entire island. Only 44 percent of the nests
hatched without being disturbed. Sand crabs entered 40.8 percent,
although this does not mean that some of these nests did not later
hatch some young.
Sand Crab. Crabs entered nests regardless of the stage of incu-
bation and condition of the nest site. It is remarkable how these
predators can locate an egg deposit after all surface signs of the nest
have been obliterated. It may be largely accidental, or connected
in some manner with the presence of the soft sand immediately over
the eggs. Newly made nests still marked by the turtle's crawl are
easily found by the crabs, which dig shallow 3- to 12-inch holes
experimentally all over the site. This sometimes results in their
finding the egg deposit. A nest that has been entered usually shows
a hole surrounded by scattered egg shells. In soft sand this entrance
hole may be gradually excavated to reach 1 foot in diameter instead
of the customary 3 or 4 inches. The crabs, sometimes a dozen in
the same nest, may either eat the eggs in the nest or remove them to
nearby dunes or to their permanent burrows. Although only one
crab may discover an egg deposit, sometimes a dozen more may move
into the area within the space of a week and dig their burrows around
the original one. The number of sand crabs on the Cape Island beach
was large, and appeared to be greatest on those types of beach having
the most nests. Whether this was due to the abundance of nests

Vol. 4


or to more favorable environment for the crabs is not known. The
wide sloping beach that had the most nests (1 every 28 feet) also had
the greatest amount of crab predation, 60.9 percent of the 110 nests
made on that type.
Raccoon. Raccoons destroyed 5.6 percent of the total number
of nests. Predation by this animal was decidedly higher in previous
years, and the decline is attributed to control measures during the
winter months. A wide variety of foods on wooded Bull's Island
makes raccoon depredation of turtle nests there low. On Cape Island
with its limited flora and fauna, raccoons must depend for their food
on fiddler crabs, oysters, insects, mice, bird eggs, and turtle eggs.
Twenty-four raccoon droppings collected throughout June, July, and
August from Cape Island contained remains of fiddler crabs (100
percent) with a trace of insect matter (Coleoptera). In fact, fiddler
crabs are the major year-round raccoon food on Cape Island. With
such a limited diet, it is little wonder that raccoons relish logger-
head eggs.
On Cape Island raccoons patrolled the beach and dunes singly
or in family groups of two or three. It is our belief that nest depreda-
tion was carried on by relatively few individuals who covered the
same area throughout the summer. The behavior of these animals
around nests was irregular. Many times they walked directly over
egg deposits the night they were laid, not even pausing to investigate.
Freshly made nests with crab burrows down to the eggs and shells
scattered on the surface would also fail to arouse the curiosity of
passing raccoons. Other nests were raided the night they were made
or even many days after incubation had started and the site had been
obliterated. The entire clutch of fresh eggs was usually eaten after
they had been reached through a large excavation, and the shells
scattered on the surface. Sometimes a few dozen eggs were left
intact in the bottom of the nest. Eggs that contained developing
young were broken and scattered rather than eaten, and especially
when the embryos were almost ready to emerge. Young logger-
heads are doubtlessly caught and eaten by raccoons. Around one
nest that had hatched the preceding night we found six young turtles
with their heads missing; tracks indicated this was raccoon work.
Erosion. Another agency of nest destruction on Cape Island was
erosion by the action of the surf. The periods of greatest loss oc-
curred whenever the highest monthly tides were accompanied by a
strong wind. Nests uncovered by the pounding of the surf were im-
mediately entered by sand crabs. As shown in Table 7, most wash-


ing (90 percent) occurred on the low beach below the truncate dunes,
a type that was chosen least by nesting turtles. On the other hand,
the least damage (1 percent) was on the wide sloping beach, the
type most used by the female loggerheads; this stretch of beach is
much higher than the former.


Nests opened by predators soon develop a population of flies and
beetles, attracted for feeding and egg-laying. Such concentrations
attract birds; turnstones and sanderlings have been observed feeding
around the opened nests. Small nematodes commonly develop on
broken eggs. Mites collected from the plastron sutures of a hatch-
ling loggerhead were identified as Macrocheles sp. (Parasitidae) by Dr.
Ewing of the U. S. National Museum, who stated that the group is
not parasitic and doubted "its specific association with the turtle."

Babcock, Harold L.
1937. The sea turtles of the Bermuda Islands with a survey of the present
state of the turtle fishing industry. Proc. Zool. Soc. London, series A.
vol. 107, pt. 4, pp. 595-601.
Caldwell, David K., Archie Carr, and Thomas R. Hellier, Jr.
1956. Natural history notes on the Atlantic loggerhead turtle, Caretta caretta
caretta. Quart. Jour. Florida Acad. Sci., vol. 18, no. 4, .pp. 292-302,
2 figs.
Carr, Archie, and David K. Caldwcll
1956. The ecology and migrations of sea turtles, 1. Results of field work in
Florida, 1955. Amer. Mus. Novitates, no. 1793, 23 pp., 4 figs.
Coast and Geodetic Survey, U. S. Department of Commerce
1939. Tide tables-Atlantic Ocean, for the year 1939. Washington: Serial no.
604, 313 pp.
Coker, R. E.
1906. The cultivation of the diamond-back terrapin. North Carolina Geologi-
cal Survey, Bulletin 14, 69 pp.
McAtee, W. L.
1984. The loggerhead. Nature Magazine, for January, 1934, pp. 21-22.

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