BULLETIN OF THE FLORIDA STATE MUSEUM BIOLOGICAL SCIENCES Volume 4 Number 10 THE ATLANTIC LOGGERHEAD SEA TURTLE, CARETTA CARETTA CARETTA (L.), IN AMERICA I. NESTING AND MIGRATION OF THE ATLANTIC LOGGERHEAD TURTLE David K. Caldwell, Archie Carr, and Larry H. Ogren II. MULTIPLE AND GROUP NESTING BY THE ATLANTIC LOGGERHEAD TURTLE David K. Caldwell, Frederick H. Berry, Archie Carr, and Robert A. Ragotzkie III. THE LOGGERHEAD TURTLES OF CAPE ROMAIN, SOUTH CAROLINA Abridged and annotafed by David K. Caldwell \.~8~YJ .imer-/ UNIVERSITY OF FLORIDA Gainesville 1959 The numbers of THE BULLETIN OF THE FLORIDA STATE MUSEUM, BIOLOGICAL SCIENCES, will be published at irregular intervals. Volumes will contain about 800 pages and will not necessarily be completed in any one calendar year. OLIVER L. AUSTIN, JR., Editor The publication of this number of THE BUD 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, Seagle Building, Gainesville, Florida. Manuscripts should be sent to the Editor of the BULLETIN, Flint Hall, University of Florida, Gainesville, Florida. Published 8 June 1959 Price for this issue $.70 II. MULTIPLE AND GROUP NESTING BY THE ATLANTIC LOGGERHEAD TURTLE 5 DAVID K. CALDWELL, FREDERICK H. BERRY,6 ARCHIE CARR, and ROBERT A. RAGOTUDE7 SYNORsm: Tagging result5 and studies of unlaid eggs in dissected females demonstrate that individuals of the Atlantic 16ggerhead 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 durihg the peri6d5 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 togethei during the season to nest t6- gether, no detailed observations on these points appear to have been made by biologists. Receht evidence of tagging studies proves' mul- tiple emergence and suggests group adherence of individuals. Fur- ther evidence that the eggs of a season are laid in two or more batches has beal 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. GROUP NESTING EMERGENCE In examining their tagging data on the green turtle, Chelonia mydas mydas (Linnaeus), for possible evidence of group travel, Carr and Gioyanholi (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 C-5479 (University of Florida, Principal Investigator Archie Carr) and by the Georgia Game and Fish Commission. Contributi6n number 43 from the United States Fish and Wildlife Service Bureau of Commercial Fisheries Biologi„ cal Laboratory, Brunswick, Georgia. « Fishery Research Biologist, United States Fish and Wildlife Service, Burea~ of Commercial Fisheries Biological Laboratory, Brunswick, Georgia. 1 Eormerly Associate Professor of Zoology and Director of the Uniyersity of Georgia Marine Institute, Sapelo Island,· Georgia. Present address: D6partment of. Meteorology, University of Wisconhin. 310 BULLETIN FLORIDA ·STATE MUSEUM Vol. 4 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, 1956:8) fixed t6 ·the front Ripper, including one numbered 78. On 28 May 1957, li turt»s 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 80 June 1957, 84 days after the first tagging date, Agent Robert S. Pfister of the Florida State Board of Conservation found number 28 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 malces 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 tfirtles 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. TABLE 1 NUMBERS OF ¥URTLES TAGGED AT JEKYLL ISLAND, GEORGIA, IN 1958 WITH MONEL COW-EAR TAGS, AS DESCRIBED BY CARR AND CALDWELL (1956). early J une (date uncertaih) 5 9-11 July 4 22 July 1 6 June 6 11 July 5 28 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 81·July 3 Total 72 The results of the 1958_ taggiFig studies on Jekyll Island clearly show this phenomenon of group nesting emergence by loggerheads (table 2). Eight turtles, numbers 125, 648, G47, G108, 6105, G107, 1959 ATLANTIC LOGGERHEAD SEA TURTLE 811 G108, and Glll, 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 sue- TABLE 2 RETURNS OF LOGGERHEAD SEA TURTLES TAGGED AT JEKYLL ISLAND, GEORGIA, IN 1958. (ld) DENOTES TURTLE LAID; (dnl) DENOTES TURTLE DID NOT LAY, (nd) DENOTES NO DATA ON NESTING ACTIVITY. Tag Date First Second Third Numbers Tagged Return Return Return 110 June 6 (ld) July 10 (nd) 111 June 10 (dnl) June 16 (ld) July 5 9 114 June 10 (ld) July 28 (ld) July 29 (dnl) 117 June (?) (nd) July 18 (nd) 118 June 18 (dnl) June 28 (ld) 120 June (?) (nd) July 11 (nd) 121 June (?) (nd) July 10 (nd) i23 June 13 (dnl) July 29 (ld) 125 June 18 (dnl) July 16 (ld) August 1 (ld) 186 early June (nd) June 28 (ld) July 11 (ld) 144 June (?) (nd) July 26 (ld) 147 1635 j 10 July 11 (nd) July 14 (dnl) July 26 (dnl) 630 July 10 (dnl) July 11 Od) G83 July 11 (dnl) July 28 (ld) G87 July 11 (dnl) July 15 (nd) 643 July 15 (dnl) july 28 (dnl) July 29 (dnl) July 80 (ld) G47 July 16 (ld) July 81 (ld) G49 July 16 (dnl) July 17 (ld) G102 July 16 (dnl) July 17 (dnl) July 18 (nd) Glos July 17 Od) July 80 (ld) 6105 July 17 (ld) July '80 (ld) G107 July 17 (ld) July 81 (ld) G108 July 17 (ld) July 80 (ld) Glll July'18 (ld) July 31 (dnl) August 1 (ld) Gll5 July 22 (dnl) July 28 (ld) G119 July 25 (ld) August 7 (ld) 8 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. 0 Turtle f6und dead on beach. Oviduct contained shelled aggs. 10 Turtle re-tagged when origihal tag pulled out during first fecapture. 812 BULLETIN FLORIDA STATE MUSEUM Vol. 4 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, I47-G35, and G80, but the data for this and possible other groupings are not con- elusive. 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 1980 to 1988. 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 nurribers, 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 turties on the beach at one time, then periods with only an occasional individual present be- fore anether 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. MULTIPLE NEST[NG AS SHOWN BY TAGGING RESULTS 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 1959 ATLANTIC LOGGERHEAD SEA TURTLE 313 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 recoyeries 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. A TV I[ I50- 25 &1 3 e K n N 5 B m III 25 - 5 - · I- 1 6 10 15 - 20 .25 30 35 40 45 DIAMETER (MM.) Figure 20.-Diameter-frequencies of freshly laid and ovarianeggs 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. 814 BULLETIN FLORIDA STATE MUSEUM Vol. 4 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 fumlled her mission. Carr and Giovannoli (1957: 24) reported for green turtles a similar "singlemindedness of the nesting drive," borne out by turtles number 111, 680, G87, 649, G115, and particu- larly by 643 and G102 (Table 2). Thus a turtle tagged on a given date but not known to have layed 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, 638, G48, 147-685 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 w6uld have shown comparable intervals had they been caught each time they nested. For example, reedveries of turtles 117 and 144, like the Florida returns noted above, probably represent second nesting emergences after tagging. Turtle 128 may have returned a third time. Turtle 186 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 sectibh 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 Sap610 Island, one of Which (625) was recaptured there 81 July, two nights after being tagged. She did not nest either time, but the return sup- ports the popular assumption that each turtle nests oil 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 bearing distinctive marks, apparently laid twice on Sapelo, on 18 and 28 June. The interval is shoft,- 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 1959 ATLANTIC LOGGERHEAD SEA TURTLE 815 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 turtldis.· 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 beiween nesting ventures is indicated. Turtle number 18 . 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 18, 950 feet southward; and num- ber 10, 800 feet southward. Unfortunately some of the people at Jekyll who furnished en- thusiastic codperation 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 % 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 Hendrickson (1958) for the green turtle. EVIDENCE OF MULTIPLE NESTING BASED ON UNLAID EGGS 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 desigliated 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: 891) she presumably would have laid that night. In addition to the matur-e' eggs, a second-group (II) of 182 eggs consisted of large yellow yolks, and a third, group (III) coiisisted of 316 BULLETIN FLORIDA STATE MUSEUM Vol, 4 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 p»resumably 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 5inail gfoup 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 nestihg 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 giounds 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. 1959 ATLANTIC LOGGERHEAD SEA TURTLE 317 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 artives at the rdokery. Thus, one group 6f 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 week§. 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. ACKNOWLEDGMENTS We are indebted to a number of people who furthered 6ur studies by supplying information, physieal 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 cooperatiton 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 G. King, for his cooperation in facilitating our observation during the Hights. 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. 818 BULLETIN FLORIDA STATE MUSEUM Vol. 4 William W. Anderson furnished ~s with valuable unpublisbed notes on Georgia sea turtles. Seton H. Thompson and Richard T. Whiteleather of the United Siates 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. LITERATURE CITED Carr, Archie „ 1952. Handbook of Turtles. Ithaca, N. Y.: Comstock Publishing Associates, xv + 542 pA, 37 figs., 82 pls., 28 maps. Carr, Archie, and David K. Caldwell - j 1956. The ecology and migrations of sea turtles, 1. Results of field work in Florida, 1955. Amer. Mus. Novitates, no. 1793, 28 pp., 4 figs. Carr,-Archie, and Leonard Giovahnoli 1957. The ecdlogy and migrations of sea turtles, 2. Results of field work in Costa Rica, 1955. Amer. Mus. Novitates, no. 1835, 32 pp., 18 Bgs. 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 mudas (Lind.) in Malaya and Sarawak. Proc..Zool. Soc. London, vol, 180, pt. 4, pif 455-585, 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.