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Carolina. Burll. Fla. Stat. Mr.rs. Nat. Hist. Biol. Sci.4:3 19-348. MnosovsKy, N., HoprrNs-MuRpHy. S.R., AND RrcunnosoN, J.l. 1984b. Cann, A. 1973. So Excellente a Fishe. New York: Anchor Natr-rral Sex ratio of sea turtles: seasonal changes. Science225:739-741. History Books, 280 pp. NEvrr-r-n, A., wEesrEn, w.D.. AND Bnoorcs, w.B. 1989. Nest tempera- CRnR, A.F.? AND HlntH, H.F. 1961. Social facilitation in green tr-utle tltres and duration between pipping and emergence in the logger- siblings. Anirn. Behav. 9:68-70. head sea tuftle in southeastern North Carolina. In: Eckert, S.,, CnRR, A.. nND ocnEru, L. 1960. The ecology and migrations of sea Eckeft, K., and Richardson, T. (Compilers). Proceedirrgs of the tuftles, 4. The green turtle in the Caribbean Sea. Bull. Am. Mr-rs. Ninth Annual Workshop on Sea Turtle Conservation eurd Biology. Nat. Hist. l2l:l-48. NOAA Tech. Mem. NMFS-SEFC-232,pp. I3t-l33. CHntsrErus, E. 1990. Nest emergence lag in loggerhead sea tufiles. J. Rn:, U. l9T6.Incubation and hatching slrccess in artificially incu- Herpetol. 24:400-402. bated eggs of the hawksbill turtle , Eretmoc'helt,s imbricctttt (L.). I . CnnrN, D.A., BoLreN, A.8., AND Blonxpel, K.A. 1995. Effects of E*p. Mar. Biol. Ecol. 22:91-99. beach nourishment on sea tuftles: review and research initiatives. RnvNnuD, A., nNo Ptnnu, C. 1985. Embyr onic development of the geniterl Restoration Ecology 3:95- 104. system. ln: Gans, C., and Billett, F (Eds.). Biology of the Reptilia. Vol. DrnL, B.E. 1987. Energetics and performance during nest emergence 15. Development B. New York: John wiley and Sons,pp. 149-300.
and the hatchlin gfrenzy in loggerhead sea turtl es (Caretta carettct) . SrnNoonn' E.A.., AND Sporln, J.R. 1985. Ternperature dependent sex Herpetologica 43:301 -3 I 5. determination in sea turtles. Copeia 1985 l l1-722. Dtnl,roruo, A.W. 1976. Breeding biology and conservation of hawks- WEesrEn, W.D., AND GouvErn. J.F. 1988. Predicting hatchling sex bill tr-rrtl es, Eretrnochelys intbriccttctL.,on Cousin Island, Seychelles. ratios in loggerhead sea tlutles ( Carettcr curettc) by incubation Biol. Conserv. 9: 199-215. duration. In: Schroeder, B. (Compiler). Proceedings of the Eighth ErcHeEnGER, C.R., PHrLLres, J.B., EweRr, M.A., NelsoN, C.E., AND Annual workshop on Sea Turtle Conservation and Biology. PRnNce, H.D. 1991. Effects of oxygen concentration and clutch on NOAA Tech. Mem. NMFS-SEFC-214'pp. 127-128. sex determination and physiology in red-eared slider turtles wvNErcpN' J., AND SnlvoN, M. 1992. Frenzy and postfi'enzy swim- (Trachel??-'t:r scriptct). J. Exp . Zool. 258:394-403. ming activity in loggerhead, green, and leatherback hatchling sea GEoncES, A., Lrrvrpus, C., RNo SrouuESDrJK, R. 1994. Hatchling sex in turtles. Copeia 1992:41 8-484.
the marine turtle Carettct carettcr rs determined by proportion of YNrEvn , C.L.,, AND MnosovsKy, N. I g8z.Critical periods and pivotal development at a temperature. not daily durration of exposure. J. temperatures for sexual differentiation in loggerhead sea tr.rrtles. Exp. Zool. 27 0:432-444. Can. J. Zool. 60: I 012-1016. Gonpngy, M.H.., BRRRETo, R., AND MnosovsKy, N. 1996. Estimating past and present sex ratios of sea turtles in Sr-rriname. Can. J.Zool. Receivecl: 3 June 1996 Rev,iewecl: 30 November 7 4:267 -277 . 1996 Rettisecl GurzrE, W.H.N., PRurcsrrs, G.L.. AND Pacrcnnn, G.C. 1984. Pipping ancl Acceptecl: 27 Augr-rst 1997 verslls hatching as indices of time of incr"rbation in reptiles. J. Herpetol. l8:494-496.
,J:l:il,,'J,1"',;,11;lI-5 tt 5 GvuRls, E. ( 1993). Factors that control the emergence of green tr-rftle -s I 7 o, e e 7 o, .ii3ll, lli ::l hatchlings from the nest. Wildl. Res. 20:345-353. HENpnrcKSoN, J.R. 1958. The green tuftle, Chelonia nn,clas (Linn.), in Predation Malaya and Sarawak. Proc. Zool. Soc. Lond. 130:455-535. upon olive Ridley Sea Turtles Knnevlen, J.E., AND BENNerr, S.H. l98l . Utilization of posthatching yolk (Lepidochelys olivacea) by the in loggerhead sea tuftles,, Carefta caretta. Copeia 198 I :406-41| . American Crocodile (Crocodylus acutus) KnnsvER, J. E., AN D RtcHnnnsoN, J. I. I 97 9 . Volurmetric reduction in nest contents ofloggerhead sea turtles (C arettct careftct)(Reptilia Testudines, at Playa Nancite, Costa Rica Cheloniidae) on the Georgia coast. J. Herpetol. l3:255-260. MnncovAlDr, M.A., Goop'Rey, M.H., AND MnosovsKy, N. 1997. Runy M. Onrz'.t, PTMELA T. ProrKrN2, Estimating sex ratios of loggerhead tr"utles in Brazil from pivotal AND f)avn Wvr. Ownxsl incr-rbation durations. Can. J . Zool. I 5:1 55-710. MonnEnLE, S.J., Rurz, G.J., Spornn, J.R., AND SrnNoona, E.A . 1982. I Temperature-dependent sex determination: current practices Department of Biology, Texcts A&M (Jrtit,ersit),, zDepurtntent College Stotiort, Te-ras 77843 USA; o.f threaten conservation of sea turftles. Science 216:1245-1241 . Bioscienc'e cmcl Biotecltnolog\,, plr,lcttlelphiu, MnosovsKy, N. 1968. Nocturnal emergence of hatchling sea tuftles: Dre.rel Unit,e rs it1,, Perutsylt,cutict 19104 j control by thermal inhibition of activity. Nature 220: 1338- 1339. usA; Present Aclclrerr.' l/AsA Ame.; Research Center, MS 239-7, Moffett Field, Califontia 94035 Mnosovst
marine habitat (Mazotti r practices. Biol. Conserv . 18:21I -280. and Dunson, 1984; Taplin. 1988 MnosovsKy, N., DurroN, P.H., AND WHnuone, C.P. 1984a. Sex ratios provides these predators the opportunity to exploit rnarine of two species of sea turtle nesting in Sr"rriname. Can. J. Zool. prey such as sea turtles. However, published accounts t-rf 62:2221-2239. crocodile predation on or consumption of sea turtles itre feu 586 CHEr-olunN CoNSERVATToN AND BtoLocy, Volume 2, Nantber 4 - I997
(Allen, 197 4: Limpus et al., 1983 ; Pdrez Higareda et al., month observation period, a total of I 1 turtle carcasses were 1989; Hirth et al., 1993). found of which 9 were attributed to crocodile predation. Turtles of the genus Lepidochelys sometimes display a Because carcasses were always found on the beach we as- unique nesting behavior tetmed arribada (Spanish for "ar- sumed that the crocodile's attack occuffed on land. However, dval") in which thousands of females synchronously ascend a we can not rule out the possibility that the crocodile killed the single beach on one or a few successive nights (or days) to lay turtles at sea and the carcasses washed up on shore. The their eggs (Richard and Hughes, 1912; Cornelius, 1986). observation of a crocodile stalking a nesting turtle suggests that Arribadas typically occur once a month during the nesting crocodiles capture and kill turtles in nearshore waters. The season, while some solitary nesters may nest every night. second author observed a solitary turtle emerge on the beach in Pritchard ( 1969) and Eckrich and Owens ( 1995) hypothesized the late afternoon to lay eggs, while a large crocodile (ca. 3 m that arribada behavior evolved as a predator satiation mecha- TL) remained offshore (ca. 25 m) observing the turtle from nism in which the probability of individual predation is re- shallow water (< 1 m). When the tuftle completed nesting and duced. began her return to the water, the crocodile moved towards her, During the arribado season between July and November remaining concealed in the water. As the turtle reached the of 1990, we observed and recorded evidence of predatory water's edge, two volunteers came running down the beach, activity of the American crocodile (C. acutus) upon olive sending the crocodile offto deeper water and abandoning what ridley sea turtles (L. olivacea) during the turtle's nesting season appeared to be an impending attack on the turtle. at Playa Nancite, Santa Rosa National Park, Gulf of Papagayo, Predation on adult turtles was charactenzed by frontal Pacific coast of Costa Rica. We documented: 1) the date attacks, with usually one fresh tuftle carcass on the beach at a crocodiles, their tracks, and depredated turtle carcasses ap- time. Frontal attacks by C.acutus and Morelet's crocodile (C. peared, 2) direction of crocodile tracks (leaving from or moreleli) on prey have been reported in Mexico (Casas Andreu retuming to the estualy), and 3) condition of turtle carcasses. and Guzmftn Arroyo, l9l0;Pdrez Higareda et al., 1989). In American crocodiles inhabit the estuary behind the turtle Papua New Guinea, the occuffence of a frontal attack by a nesting beach at Playa Nancite. The ca. 1.1 km stretch of beach crocodile (presumably C. porosus; species not mentioned) on is bordered by two rocky headlands, isolating the estuary, a leatherback sea turtle (Dennochelys coriacea) has been therefore making the beach the only access to the ocean for the documented (Hinh et al., 1993). Although we never observed crocodiles. The estuary is roughly divided into two separate an actual attack, "predatory events" were reported by other pools of approximately equal size that oftenjoin during the wet research personnel. They reported on one occasion a large season. A larger estuary is present at Playa Naranjo approxi- crocodile emerging quickly from the surf and attacking a mately 1.5 km to the south and a smaller estuary and beach, female turtle on the beach. The frontal attack was initiated at the Playa Tule, is ca. 2 km to the nofth. The crocodiles inhabiting left forelimb, which was ripped completely off by the aggres- the estuary system of Playa Naranjo occasionally visit Playa sive rolling which ensued, exposing the turtle's viscera. Aside Nancite (Cornelius, I 986). from this one report, the condition of the turtle carcasses Crocodiles were observed in nearshore waters, in the sometimes made it difficult to positively determine their estuary, and on the beach. Although none of the crocodiles gender, but most were presumed to be females. were marked or tagged for subsequent identification, we Bite widths, the shape of teeth holes, and the presence of estimated that approximately l5 individuals frequented Playa teeth scrapes on the turtle's shell as well as the direction of the Nancite. One large animal (ca. 3 m total length (TL), gender attack helped to differentiate between either a shark or a undetermined),2-3 subadults ( 1.5-2m TL), and the remainder crocodile attack. An attack by C. acutus was characterized by juveniles (0.5-0.9 m TL) and hatchlings (< 30 cm TL), a naffow bite width with conical teeth holes anteriorly in the inhabited the estuary behind the beach during the arribada car apace in a defi nite pattern, and u su all y w ithout teeth scrape s . season. Size classes defined here follow those described by Turtle carcasses were always gutted and lacked the front Mendez and Casas Andreu (L992). flippers and usually the head. A volunteer reported observing During the 5 month study period, four arribadas occurred a large crocodile with its head inside the turtle's body cavity, with each involving approximately 1000 to 20,000 turtles. The consuming the viscera. presence of crocodile tracks on the beach during arribada,s was American and Morelet's crocodiles in Mexico have been difficult to determine due to the large number of turtles using reported to allow their prey to decompose in order to facilitate the beach. Also the high tide sometimes eroded crocodile dismemberment for consumption (Casas Andreu and Guzmdn tracks making them indistinct. When crocodile tracks were Arroyo,, I9l0;P€rez Higareda et al., 1989), but we did not identified we observed that 1) tracks indicating seaward or observe this behavior at Nancite. Turtle carcasses were found landward movement did not always have a complementary set on the beach or in the nearshore vegetation. They were not of tracks in the opposite dircction, and 2) the single large found in or near the estuar!, suggesting that they had been crocodile's exit to sea and subsequent return did not always consumed shortly after being attacked. coincide with the presence of a turtle carcass on the beach. In addition to crocodile predation on adult turtles, sub- Turtle carcasses were usually found either 3l days prior adult and juvenile crocodiles were seen consuming turtle hatchlings. One subadult crocodile (ca. 1.5 m TL) was ob- ::.::,::';'':::ffi L:.:::""'1"#':rTi,r;:::ff;,il?:;:'; served at the edge of the shore eating hatchling turtles as they Nores AND FrElo REponrs 587
entered the sea. Juvenile crocodiles were most evident when
hatchling turtles were emerging nests C t'l e t o n i ( .r from their on the beach m'l,;;?T; r ) r 8 7-5 e ] and during periods of heavy rain. [l:i: il l'l ?:llf ;t;,.'Ji.l; The successful attacks on solitary tuftles and the absence of predation on arribacla turtles suggests that arribada behav- Growth and Reproductive Estimates ior may deter predation by crocodiles. Observations from the from Altigator Snapping Turtles, present study make it difficult to accurately assess the preda- Macroclemys temminckii, taken by tory pressures American crocodiles impose on the olive ridley Commercial Harvest in Louisiana sea turtle population at Playa Nancite. However, the depreda- tion of I or 2 sea turtles by American crocodiles between AnroN D. TucxERl AND Krvm N. SroAN2.3 arribadas ranging from 1000 to 20,000 turtles is at alow level, having little or no effect on the nesting population of olive l Zoolo gy Depctrtntent, (Jniversiy' ef Queensland, ridleys at Playa Nancite. Instead, predation of crocodiles upon 2U.S. Brisbarte, Queensland 4072 Australia; Depctrtment turtles at Playa Nancite may actually enhance the survival of o.f the Interior, Fish ancl Wildlife Service, 1500 l{orth Decatur this population of crocodiles which persists as a small, frag- Boulevarcl #01, Las Vegus, Ir{evqcls 89108 USA mented remnant of the original population on the Pacific coast. IFux: 702-646- ] 554; E-mail: kevin_sloan@ rnail.fits.gsvl; 3 Comesponding Author .fbr Reprint Recluests Acknowleclgments. - We thank all the volunteers who worked at Playa Nancite during the course of this study for their The alli gator snapping turtle (M a c ro c I e nry s t e mtninc ki i ) repofted observations. We would also like to thank J.P. Ross is a large freshwater chelydrid restricted to drainages of the for his critical review of this manuscript. This project was Gulf Coastal Plain and the Mississippi River Valley of the supported by grants to DWO from the National Science USA ([.ovich, 1993). In comparison to other North Ameri- Foundation (BNS-9045319 and IBN-9 124014). can turtles, many aspects of its biology remain poorly known (Ernst et al., 1994) even though the species has been ex- Literature Cited ploited heavily by the soup indusrry for decades (Pritchard, 1989). Populations of Macroclent_),,s are considered low or ALLEN, G.R. 1914. The marine crocodile, Croco(h,lus porosLts, from depleted because of overharvesting, yet the actual Ponape, Eastern Caroline Islands with notes on food habits of status is crocodiles from the Palau Archipelago. Copeia 1974:553. poorly known (George, 1987). Cnsns ANonEu, G., AND GuzH,rAN Annovo, M. 1970. Estado actual de Many biological details about Mctcroclenrts have been las investigaciones sobre cocodrilos mexicanos. Bol. Inst. Nal. learned by analyzing specimens gathered by comrnercial Invest. Biol. Pesq., Ser. Divulgacion 3:l-50. turtle trappers (Dobie, l97l; Pritchard, 1989; Sloan and ConNel-tus, S.E. 1986. The Sea Turtles of Santa Rosa National Park. Lovich, 1995; Sloan et ol., 1996). Ancillary information Hermanos Ramos, Madrid. gleaned from commercial harvesting provides useful, albeit EcrcnrcH, C.E., AND OwENs, D.W. 1995. Solitary versus arribada fragmentary data, in situations analagous to salvage arche- nesting in the olive ridley sea turtl es (Lepidochelt,s olivacea): atest ology. There are compelling reasons to collect and report of the predator-satiation hypothesis. Herpetologica, 5 l:349-354. salvage biology whenever a harvested species is incom- Hrnru, H.F., Kasu, J., AND MnLR, T. 1993. Observations on a pletely leatherback turtl e, Dennochelys coriacea, nesting population near known or of conservation concern. Piguwa, Papua New Guinea. Biol. Cons. 65:77-82. In this paper we summarize reproductive and growth Ltueus, C.J., PnRvENTER, C.J., BnrsR, V., RNo FLERv, A. 1983. The data gathered from a large sample of Macroclentys that were Crab Island seatufile rookery in the northeastem Gulf of Carpentaria. processed at a commercial facility in Louisiana in 1986. The Austral. Wildl. Res. l0: 173-184. data were compared to a similar study conducted two de- Mnzorrr, F.J., AND DuNsoN, W.A. 1984. Adaptations of Crocodylus cades earlier in the same region (Dobie , l9l l). Because ctcutus and Alligutor for life in saline water. Comp. Biochem. growth and reproductive parameters are vital elements in the Physiol .19A:641-646. recovery plans for Macroclenrys, the information has impli- MEruopz DE LA Cnuz, F.R., AND Cnsns ANnnpu, G. 1992. Status and cations for the proposed size limits in commercial harvesting distribution of Crocodyl6lt ctcutus on the coast of Jalisco, Mexico. of the species. Anal. Inst. Biol. UNAM, Ser. Zool.63(l ):125-133. PexzzHtcnnEnA, G., RnNcEr- RnNcer-, A., SvlrH, H.M., AND CHrszRR, Methods A processing facility in Jonesville, Louisi- D. 1989. Comments on the food and feeding habits of Morelet's ana, saved Macroclemys viscera and carapaces which were
crocodiles. Copeia 1989: 1039- l04l . bagged, labelled, and frozen for later analysis. Both sexes PrurcHnno, P.C.H. 1969. Sea turtles of the Guianas. Bull. Florida were collected initially in March and April, but from May to State Mus. Biol. Sci. 13(2):85-140. October, only females were saved by the processor because RlcHnno, J.D., AND Hucups, D.A. 1972. Some observations of sea of limited freezer space, even though both sexes were still turtle nesting activity in Costa Rica. Mar. Biol . 16(4):297-309. processed. Sample sizes varied because some individual Taeux, L.E. 1988. Osmoregulation incrocodilians. Biol. Rev. 63:333-331. samples were incomplete, e.g., the carapace was salvaged Receivecl: 9 June 1996 but not the viscera. Reviewecl: 6 April I99l Midline carapace length (ML, straightline measure- Revisecl cmcl Accepted:28 June 1991 ment to the nearest 0. I cm) was used for analyses of bodv