Caretta Caretta) Nests Becomes a Useful Strategy

When Relocation of Loggerhead Sea Turtle (Caretta caretta) Nests Becomes a Useful Strategy

Joanna Grand; Steven R. Beissinger

Journal of Herpetology, Vol. 31, No. 3. (Sep., 19971, pp. 428-434.

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http://www.jstor.org/ Mon Oct 30 21:10:46 2006 428 SHORTER COMMUNICATIONS servations of basking toads difficult. However, if bask- OLSON,D. H. 1989. Predation on breeding western ing is part of the repertoire of adult boreal toad be- toads (Bl~foboreffi). Copeia 2~391-397. havior, it warrants further investigation. PRITCHARD,P. C. H., AND W. F. GREENH~D1968. The Ackt~m~ledgerr~ents.-Thisresearch was funded by the sun and the turtle. Internat. Turtle Tortoise %c. 12: National Biological Service's Global Change Research 2Cb25. Program. We thank Rocky Mountain National Park for RASTOGI,R. K., AND L. IELA.1980. Steroidogenesis and spermatogenesis in anuran amphibia: A brief sur- permits and logistical support; Cheley Colorado Camps for parking space and banana bread; Mike Gil- vey. 111 G. Delrio and J. Brachet (eds.), Steroids and their Mechanism of Action in Non-Mammalian Ver- lespie of the Natural Resources Conservation Agency for snow and temperature data; Robert Espinoza for tebrates, pp. 131-146. Raven Press, New York. ROME,L. C., E. D. STEVENS,AND H, B, JOHN-ADLER. the loan of the thermometer; Tom Stanley, Brian Fitz- gerald and Max Forgensi for assistance in the field; 1992. The influence of temperature and thermal ac- and Gordon Rodda, Cindy Carey Marty Pancek-Roes- climation on physiological functions, 111 M. E. Feder sler and three anonymous reviewers for commenting and W. W. Burggren (eds.), Environmental Physi- on the manuscript, ology of the Amphibians, pp. 18S205. Univ. Chi- cago Press. Chcago, Illinois. TRACY,C. R. 1975. Water and energy relations of amphibians: insights from mechanistic modelling. 111 D. BRADFORD,D. F. 1984. Temperature modulation in a M. Gates and R. %her1 (eds.), Perspectives in Bio- high-elevation amphibian Rnnn muscosa. Copeia physical Ecology, pp. xxx-xxx. Springer-Verlag, Inc., 1984:966-976. New York. BRA~STROM,B. H. 1979. Amphibian temperature TRACY,C. R., K. A. CHRISTIAN,M. P. O'CONNOR,AND regulation studies in the field and laboratory. C. R. TRACY.1993. Behavioral thermoregulation Amer. Zool. 19~345-356. by Bufo mnericanus: the importance of the hydric BROTHERS,D. R. 1994. Bujo boreas (Western toad). Pre- environment. Herpetologica, 49~375-382. dation. Herpetol. Rev. 25:117. U.S. FISHAND WILDLIFESERVICE. 1995. Endangered CAMPBELL,J. B. 1970. Life history of Blcfo boreffiboreffi and threatened wildlife and plants: 12-month find- in the Colorado Front Range. unpubl. Ph.D. Diss., ing for a petition to list the southern Rocky Moun- Univ. Colorado, Boulder. tain population of the boreal toad as endangered. CAREY,C. 1978. Factors affecting body temperatures Fed. Reg. 60:15281-15283. of toads. Oecologia 35~179-219. VANOORDT, P. G. W. J. 1960. The influence of internal CORN,P. S. 1993. Bufo boreffi(boreal toad). Predation. and external factors in the regulation of the sper- Herpetol. Rev. 24:57. matogenetic cycle in amphibia. Symp, Zool, Lon- -, M. L. JENNINCS,AND E. MUTHS.1996. survey don, no. 2:29-52. and assessment of amphibian populations in ZAPATA,A. G., A. VARAS,AND M. TORROBA.1992. Rocky Mountain National Park. Northwest. Nat. In Seasonal variations in the immune system of lower press. vertebrates. Immunology Today 13:142-147. HOPPE,D. M. 1979. The influence of color on behavioral thermoregulation and hydroregulation. In E. Accepted 6 April 1997 H. Burtt, Jr. (ed.), The Behavioral Significance of Color, pp. 3748. Garland STPM Press, New York. JORCENSEN,C. B. 1992. Growth and reproduction. ln M. E. Feder and W. W. Burggren (eds.), Environ- mental Physiology of the Amphibians, pp. 439- 466. Univ Chicago Press. Chicago, Illinois. KAGARISESHERMAN, C. 1980. A comparison of the natural history and mating systems of two anurans: Yosemite toads (Bufo canorus) and black toads (Bufo When Relocation of Loggerhead Sea exsul). Unpubl. Ph.D. Diss., Univ. Michigan, AM Ar- Turtle (Caretta caretta) Nests Becomes a bor. Useful Strategy -, AND M. L. MORTON.1993. Population declines of Yosemite toads in the eastern Sierra Nevada of JOANNA GRAND^ AND STEVENR. BE~sS~NGER,'Yak California. J. Herpetol. 27186-198, School of Forestry aid Enz~ironnmtdStudies, 205 Prospect KLUCER,M. J. 1978. The evolution and adaptive value Street, New Hmn, Connecticut 0651 1, USA. of fever. Amer, %I. 6638-43, LILL~VHITE,H. B., P. LICHT,AND P. CHELGREN.1973. Many populations of marine turtles were once The role of behavioral thermoregulation in the abundant, and now are threatened because of anthro- growth energetics of the toad, (Blifi boreus). Ecology pogenic factors (National Research Council, 1990). 54:375-383, LOFTS, B. 1984. Amphbians. 111 G. E. Lamming (ed,), Marshall's Physiology of Reproduction, 4th ed., Vol. I Present Address: Department of Anthropology, I, pp. 127-205. Edinburgh: Churchill Livingstone. American Museum of Natural History, Central Park MULLALLY,D. P. 1958. Daily activity of the western West at 79th Street, New York, New York 10024, USA toad. Herpetologica 14129-31. E-mail: [email protected] -, AND J. D. CUXXIXGHAM.1956. Aspects of the Present Address: Division of Ecosystem %iences, thermal ecology of the Yosemite toad. Herpetologica Hilgard Hall #3110, University of California, Berkeley, 12:574. California 94720-3110, USA. SHORTER COMMUNICATIONS 429

Management of these populations has generally fo- TABLE1. Matrix A is the five-stage Leslie matrix for cused on protection of eggs and hatchlings, perhaps loggerhead sea turtles without TEDs use. Matrix B is because of their accessibility and ease of monitoring the Leslie matrix with TEDs use. Both are based on the (Crouse et al,, 1987). However, there has been increas- matrix used in Crowder et al. (1994) and assume a 111 ing concern in recent years over the effectiveness of sex ratio. Assuming a 2.1:l ratio changed the fecundity early stage protection, given limited resources for conservation (Crowder et al., 1994). value of subadults to 6.344 (without TEDs) and 8.054 Demographic models have shown that the large ju- (with TEDs), and of adults to 84.179 (without TEDs) venile and adult stages are most important for pop- and 91,222 (with TEDs). *Mean survival probabilities ulation growth and should be the focus of future con- are shown for both in situ and relocated eggs respec- servation efforts (Crouse et al., 1987; Crowder et al., tively on southeastern US. beaches only. 1994; Heppell et al., 1996). Focusing conservation efforts on the egg and hatchling stage would do less to Matrix A: Without TEDs ensure population maintenance and growth than en- forcing the use of Turtle Excluder Devices (TEDs), 0.000 0,000 0.000 4.665 61.896 0.185/0.580* 0.703 which are trap-door devices that allow sea turtles to 0.000 0.000 0.000 0,000 0.047 0.657 0.000 0.000 escape from shrimping nets (National Research Coun- 0,000 0.000 0.019 0.682 0.000 cil, 1990). The incidental capture and drowning of 0.000 0.000 0.000 0.061 0.809 large juveniles, subadults, and adults in shrimp trawls now accounts for more sea turtle deaths than all other Matrix B: With TEDs human activities combined (National Research Coun- cil, 1990). Protection of eggs and hatchlings has been criticized as being a "half-way technology" in certain cases, since it may do nothing to mitigate the direct causes of decline of some turtle populations (Frazer, 1992). Hatchery programs may only serve to put more turtles into an environment in which it is increasingly difficult to survive (Frazer, 1992). Despite criticisms, the relocation of sea turtle nests and means and standard errors were calculated for to protected corrals remains a commonly used strat- loggerhead nesting beaches around the world. Means egy around the world (eg, Blanck and Sawyer, 1981; and standard errors were also calculated for south- Wyneken et al., 1988; Eckert and Eckert, 1990; Frazier, eastern United States populations only. We used 1993). Eggs are removed from the natural nest either paired Wilcoxon signed ranks tests (Z) to determine during or shortly after oviposition, placed in buckets if hatching success differed by management regimes or bags, and transported to a protected corral on the for beaches with paired data. Only studies that re- beach for incubation (Wyneken et al., 1988). Trans- ported the methods used to collect hatching rate data, plantation of nests to sites which are less conspicuous and included at least 30 nests that were incubated in to predators is another commonly used method of situ or in protected or inconspicuous beach sites, were nest protection (Stancyk et al., 1980). Ideally, time in included in the analysis. Because protected nests and transport and handling is kept to a minimum, es- nests that produce hatchlings or have signs of preda- pecially between 36 h and 45 d after oviposition, to tion may be easier to locate and inventory, sampling mitigate the effects of movement-induced mortality bias in reported hatching rates is a problem which (Limpus et al., 1979; Parmenter, 1980; Blanck and Saw- may compromise the usefulness of some data. In ad- yer, 1981; Wyneken et al., 1988). Hatchlings are re- dition, given the variety of methods used to measure leased soon after emergence at a variety of locations hatching success, reported rates may overestimate the along the beach so as not to attract an excess of pred- number of hatchlings that actually survive. ators to one area. We used the deterministic, stage class population Many nesting beaches have extremely high rates of model developed by Crouse et al. (1987) and modified egg mortality (Stancyk et al., 1980; Hopkins et al. in by Crowder et al. (1994). These models use Frazer's Iverson 1991; Erk'akan 1993; Gil in Frazier, 1993). On (1983a, b, 1984; 1986; 1987) estimates for survivorship certain beaches the level of egg mortality may even and fecundity of a loggerhead population on Little reach 100Â°/(Blanck and Sawyer, 1981). We used a Cumberland Island, Georgia and predict a rate of de- population model adapted from Crouse et al. (1987) cline of approximately 5% per year. A five-stage life and Crowder et al. (1994) in this paper to examine the table was used to construct the Leslie matrices effects of nest relocation on loggerhead turtle popu- (Crowder et al., 1994). The original seven-stage model lation growth with and without the use of TEDs, and (Crouse et al., 1987) was reduced to a five-stage model quantify the level of in situ egg mortality at which because the last three stages had the same annual sur- nest relocation becomes essential for the continued vivorship estimates (Crowder et a]., 1994). Since log- survival of loggerhead populations. gerhead eggs incubate for only approximately 8 wk, Estimates of hatching success of eggs in situ (i.e., the egg and hatchling stages were combined into one the percentage of surviving eggs that hatch, excluding stage as the model was based on a postbreeding cen- those that were depredated or poached), hatching suc- sus with a one-year projection interval (Noon and cess of eggs relocated to corrals, and survivorship of Sauer, 1992). Matrix elements were calculated accord- eggs in situ (i.e., the percentage of all eggs laid that ing to the formulas of Crowder et al. (1994).The mod- survived to hatch, including those that were depre- el assumes that all individuals within a stage are sub- dated or poached) were compiled from the literature, ject to the same survival probability and length of time SHORTER COMMUNICATIONS

TABLE2. Hatching success and egg surv~valfor loggerhead sea turtles (n > 30 nests). *Hatching Success In Situ = the percentage of surviving eggs that hatch, excluding those that were depredated or poached. ** Hatching Success Corral = the percentage of surviving eggs relocated to the corral that hatch. *** Survivorship In situ = the percentage of all eggs laid that survived to hatch, including those that were depredated or poached.

Hatching Hatching Surviv- Success Success orsh~p Location 111 Situ* Corral** 111 Situ8** %urce Mon Repos, Australia Limvus et al., 1979 Mon Repos, Australia ~imbuset al.; 1983 Masirah Island, Oman Ross and Barwani, 1982 Dalyan Beach, Turkey Erk'akan, 1993 Fethiye Beach, Turkey Baran and Turkozan, 1996 Goksu Delta, Turkey Peters et al., 1994 Kiparissia Bay, Greece Margaritoulis, 1988 Litoral Central, QR, Mex Gil in Frazier, 1993 Litoral Central, QR, Mex Zurita et al. in Frazier, 1993 Litoral Central, QR, Mex Zurita et al., 1993 Isla Cozumel, QR, Mex Zurita and Miranda, 1993 Tongaland, South Africa Hughes, 1974 Praia do Forte, Bahia, Brazil Marcovaldi and Laurent, 1996 Atlantic Coast, USA Hopkins et al. in Iverson, 1991 Jekyll Island, GA, USA Wyneken et al., 1988 Little Cumberland Island, GA, USA Richardson, 1978 Little Cumberland Island, GA, USA Christens, 1990 Little Cumberland Island, GA, USA Christens, 1990 Ossabaw Island, GA, USA Blanck and Sawyer, 1981 Canaveral Nat. Seashore, FL, USA Wyneken et al., 1988 Melbourne Beach, FL, USA R. Owen, pers. comm. Melbourne Beach, FL, USA Owen et al. in Van Buskirk and Crowder, 1994 Kiav.,ah Island, SC, USA Talbert et al., 1980 Kiawah Island, SC, USA Talbert et al., 1980 Kia~~ahIsland, SC, USA Pinckney, 1990 Kiawah Island, SC, USA Stancyk et al., 1980 Cedar Island, SC, USA Stancyk et al., 1980 Cape Island, SC, USA Andre and West, 1981 Cape Island, SC, USA Hopkins in Andre and West, 1981 Cape Romain, SC, USA Caldwell, 1959

in each stage (Crouse et al., 1987), su~ivorshpand Two stage-structured matrices were constructed to fecundity remain relatively stable from year to year, no represent survivorship ~~ithand ~~ithout the seasonal density dependence, and a 111 sex ratio (Mrosovsky, use of TEDs in offshore waters (Table 1). Surt~ivorship 1984; Frazer, 1986; Crouse et al., 1987; Crowder et al., with TEDs was estimated using the prediction that 1994). Although little is known about the sex ratio of "seasonal offshore" TED regulations may reduce the Little Cumberland Island population, a 1:l ratio was trawling related mortality by about two-thirds assumed because Mrosovsky (1984) reported that log- (Crowder et al., 1994). Population growth rate (A) was gerhead populations in South Carolina and Georgia ex- calculated for a population with a 111 and a 2.1:l sex hibit close to the expected 1:l ratio when averaged over ratio, with levels of egg survivorship ranging from 0 the entire nesting season. However, several studies have to 1, using MATLAB (1992) to determine the domi- shown that loggerhead populations in Florida exhibit nant eigenvalue. female-biased sex ratios while more northern popula- Average in situ survivorship and corral hatching tions may exhibit male-biased sex ratios (Mrosovsky success estimates for southeastern U.S. populations and Provancha, 1989, 1992; Wibbels et al., 1991). It is %,ere combined with Frazer's (1983b) estimate of sur- unclear whether the loggerheads nesting along the vival from hatching through the first year of life (0.84) southeastern US. constitute one large interbreeding to obtain an overall value for first stage survivorship population or several genetically distinct ones (Mrosov- on southeastern US. beaches. These values of first sky, 1988; Mrosovsky and Provancha, 1989, 1992; Bow- stage survivorship were then inserted into the model, en et al., 1993). However, since 90% of the turtles nest- since the model is based on data from the loggerhead ing in the southeastern US. nest in Florida (Murphy population which nests on Little Cumberland Island, and Hopkins in Mrosovsky and Provancha, 1992), we Georgia. Time to extinction for the population was also ran simulations with a sex ratio of 2.1:1.0, whch predicted by using a spreadsheet to project the pop- was reported for immature loggerheads captured off ulation of lo6 turtles (Crowder et al,, 1994) until less the coast of Florida (Wibbels et al., 1991). than one individual remained in each stage class. SHORTER COMMUNICATIONS 431

1 With TEDs

1 Without TEDs

Survivorship of Eggs

FIG. 1. Lambda for the loggerhead sea turtle as a function of egg survivorship in situ (the percentage of all eggs laid that survived to hatch, including those that were depredated or poached) both with and without the use of TEDs. Egg survival probabilities were combined with the survival from hatching through the first year of life to calculate lambda. The darkened symbols represent the lambda values for a southeastern loggerhead population under the four management scenarios. A) using a 1:l sex ratio (above). B) using a 2.l:l sex ratio (below). SHORTER COMMUNICATIONS

While this number probably overestimates the current firmed (Crouse et al., 1987). The most efficient way to size of turtle populations, a more accurate estimate reverse the decline of a loggerhead population is was not available and we were mainly concerned with through reduction of mortality in the older life stages relative differences between scenarios. (Crouse et al., 1987, Crowder et a]., 1994). Nest pro- Hatching success and survivorship of loggerhead tection alone will only postpone extinction in popu- nests varied around the world and were affected by lations that are heavily exploited by shrimp trawling. egg management strategies (Table 2). Based on pub- Nevertheless, employing nest relocation strategies lished reports, hatching success of eggs in situ (? = alone appeared to delay extinction by more than 100 0.742 :r 0.029%) was greater than hatching success of yr, which is a significant period. Furthermore, the use eggs relocated to corrals (2 = 0.686 Â 0.023%). This of TEDs alone did not cause the southeastern logger- difference was significant (Z = 2.10, N = 8, P = 0.035) head population to increase. Only the concurrent use for beaches where hatching success was measured of TEDs and relocation was effective in causing the both in corrals and in situ. Survivorship of eggs in population to grow. situ (% = 0.377 0.073Â¡!0 was lower than hatching Although the implementation and enforcement of success of relocated nests (2 = 0.686 2 0.023%), but TEDs use should be emphasized for populations there was high variability in mortality rates of eggs heavily affected by shrimping activities (Crowder et left in situ on different beaches. Survivorship of eggs al., 1994), this technology should not be considered relocated to corrals tended to be greater (Z = 1.75, P the sole solution to sea turtle population declines if = 0.08) than for eggs left in situ at five beaches where egg mortality is high. Through the use of demograph- both rates were measured. Survivorship of eggs in ic models such as this one, it is clear that nest protec- situ for eight beaches in the southeastern U.S. aver- tion must also remain a priority on beaches with high aged 0.219 Â 0.09%. egg mortality. Given the limited resources of many Evaluating lambda for loggerhead sea turtles in the conservation programs, it is important to continually southeastern U.S. under a variety of levels of reproduc- monitor poaching and predation levels, so that nest tive success and a 1:l sex ratio predicted that the level relocation is implemented only when crucial to the of egg survivorship necessary to maintain a stable log- continued existence of the loggerhead population. In gerhead population (A = 1.00) with the concurrent use addition, the benefits of hatchery programs will only of TEDs was 43% (Fig. 1A). Egg survivorship below be apparent if proper techniques are used in trans- this value, resulted in population declines despite the porting nests, maintaining the hatchery, and releasing use of TEDs. For a population with a 2.1:1 sex ratio, the hatchlings. level of egg survivorship necessary to maintain a stable Since in situ nests had higher hatching rates than population was 32% (Fig. 1B). relocated nests, nest protection techniques that do not Population growth was highly impacted by popu- involve relocating nests may also be appropriate on lation management (Fig. 1). Lambda values never ex- some beaches. There are many methods of in situ nest ceeded 0.96 without the use of TEDs. However, neither protection available that may provide more consistent did the use of TEDs alone result in increasing popu- hatching rates by reducing the effects of movement- lations (A = 0.968 for a 1:l sex ratio; A = 0.982 for a induced mortality of eggs, such as screening, caging, 2.1:1 sex ratio). Only when TEDs were used in con- and predator removal. Stancyk et al. (1980) review junction with relocation of eggs did lambda exceed several of these techniques. Nevertheless, we have as- 1.0. Time to extinction for a population with a 1:l sex sumed that hatchlings restrained by nest protection ratio was 114 yr with no management, 229 yr with methods from entering the sea immediately after only relocation, and 410 yr with only the use of TEDs. hatching will be as fit as those that enter immediately. Relocation of loggerhead nests does appear to lower This assumption desperately needs to be tested to hatching success (Table 2). However, when loss of eggs evaluate the ultimate success of hatchery programs because of poaching and predation is included in the and other forms of nest protection. overall estimate of egg survivorship in situ, relocated Because of uncertainty in many of the loggerhead nests can have a much higher survival probability on turtle demographic parameters, and the problems as- many beaches. Even with the use of TEDs, some type sociated with generalizing survival probabilities from of nest protection appears to be necessary to prevent one population to another, it is difficult to know the extinction if average egg survivorship falls below 43% accuracy of our predictions. The lack of data on sur- for a population with a 1:l sex ratio (Fig. 1A) or 32% vivorship of both in situ and relocated eggs on the for a population with a female-biased sex ratio (Fig. same beach is also problematic in terms of conducting 1B). Levels of egg survival much lower than this do a statistical comparison of these two conditions. With- occur on many nesting beaches where poaching and out adequate data, it is uncertain how effective relo- predation rates are high (Table 2). It is on these beach- cation strategies actually are. However, the demo- es especially that nest protection should be imple- graphic model we have presented illustrates the fact mented, since TEDs alone will not prevent extinction. that we cannot rely exclusively on solutions which im- Uncertainty in national and international compliance prove survival in one life stage without consideration with TEDs regulations may further raise the critical of the others, if we hope to prevent the extinction of level of egg survival necessary to prevent extinction. long-lived species. Non-compliance is a reality within the shrimping in- dustry, since some shrimpers argue that as much as 4cknm~kd^Ji1t~nts.-Wewould like to thank Josh Van one-third of their catch is lost through TEDs (Mc- Buskirk, Larry Crowder and Selina Heppell for shar- Donald, 1990). ing their data and providing helpful suggestions, Scott Nest relocation alone did not cause the loggerhead Stoleson for help with literature, and Bill Wcinstein for population to increase, as previous analyses have con- his computer support. The critical comments of C. SHORTER COMMUNICATIONS

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male, egg and hatchling sizes in the loggerhead or population that is to be listed by conservation or turtle, Caretta caretta (L.), nesting at Kiawah Island, government agencies as sensitive, rare, threatened, or South Carolina, USA. Bull. Mar. Sci. 47:670-679. endangered. A study on the status, distribution and RICHARDSON,J. I. 1978. Results of a hatchery for in- biology of the San Diego Horned Lizard, Phrynosoma cubating loggerhead sea turtle eggs on Little Cum- coronatum blainvillii for the California Department of berland Island, Georgia. Florida Mar. Res. Publ. 33: Fish and Game (CDFG) led me to investigate the sta- 15. tus of the subspecies of l? coronatum and the closely Ross, J. P., AND M. A. BARWANI.1982. Review of sea related P. cerroense. Phrynosoma c. blaim'illii. was listed turtles in the arabian area. In K. A. Bjorndal (ed.), as a "Species of Special Concern" by the CDFG and a Biology and Conservation of Sea Turtles, pp. 373- candidate for listing as a Category I1 species by the 383. Smithsonian Institution Press, Washington, Federal Government. I report here my observations, D.C. which suggest that there are no valid subspecies of STANCYK,S. E., 0. R. TALBERT,AND J. M. DEAN.1980. Phrynosoma coronatunz. Nesting activity of the loggerhead turtle Caretta ca- The Coast Horned Lizard, Phrynosow~a coronatum, retta in South Carolina, 11. Protection of nests from occurs from the Sacramento Valley southward to the raccoon predation by transplantation. Biol. Con- tip of Baja California. Jennings (1988a) recognized five serv. 18:289-298. subspecies although neither Stebbins (1985) nor Gris- TALBERT,0. R., JR.,S. E. STANCYK,J. M. DEAN,AND J. mer and Mellink (1994) recognized subspecies. The M. WILL.1980. Nesting activity of the loggerhead closely related l? cerroense occurs on Cedros Island on turtle (Caretta caretta) in South Carolina I: A rook- the Pacific side of Baja California. The latter was con- ery in transition. Copeia 1980:709-718. sidered a species by Jemings (1988b) by virtue of its VAN BUSKIRK,J., AND L. B. CROWDER.1994. Life-his- isolated island distribution and short tail with only 19 tory variation in marine turtles. Copeia 1994:66- caudal vertebrae (Presch, 1969). 81. The San Diego Horned Lizard, l? c. blainvillii, WIBBLES,T., R. E. MARTIN,D. W. OWENS,AND M. S. (SDHL) occurs from northwestern Baja California, AMOSS,JR. 1991. Female-biased sex ratio of im- Mexico into California in San Diego, Orange, River- mature loggerhead sea turtles inhabiting the At- side, Los Angeles and San Bernardino Counties. In lantic coastal waters of Florida. Can. J. Zool. 69: northwestern Los Angeles County, P. c. blainzdlii in- 2973-2977. tergrades with the northern subspecies P. c. frontale. WYNEKEN,J., T. J. BURKE,M. SALMON,AND D. K. PED- The San Diego Horned Lizard is found only in the ERSON.1988. Egg failure in natural and relocated California coastal and inland regions from sea level to sea turtle nests. J. Herpetol. 22:88-96. 8000 feet, hence from grasslands and Coastal Sage ZURITA,G., J. C., R. HERRERA,AND B. PREZAS.1993. Scrub (CSS) vegetation to pine forest. The SDHL oc- Biologia y conservation de las tortugas marinas en curs in sandy, open areas, but also in dense, old el litoral central de Quintana Roo, Temporada growth chaparral on 70Â slopes (Brattstrom, unpubl. 1992. In J. Frazier (ed.), Memorias del IV Taller Re- data). It is the only horned lizard within its range. It gional Sobre Programas de Conservacion de Tor- meets the Desert Horned Lizard, P. platyrhinos, at the tugas Marinas en la Peninsula de Yucatan, pp. high desert edge north of the San Gabriel Mountains 169-179. Universidad Autonoma de Yucatan, Me- from Palmdale to Adelanto. The ranges of the two rida, Mexico. species apparently do not overlap as the SDHL is re- -, AND J. L. MIRANDA.1993. Comite de protec- stricted here to the Juniper-Desert Chaparral habitat don de las tortugas marinas en la isla de Cozumel. and the Desert Horned Lizard is found mostly in cre- In J. Frazier (ed.), Memorias del IV Taller Regional osote bush scrub vegetation. A similar close proximity Sobre Programas de Conservacion de Tortugas may occur in the little San Bernardino Mountains and Marinas en la Peninsula de Yucatan, pp. 159-168. in northwestern Joshua Tree National Monument. The Universidad Autonoma de Yucatan, Merida, SDHL is separated by range and habitat from the oth- Mexico. er two California horned lizards; l? mcallii of the low desert and l? douglassii of the Modoc-Klamath plateau Accepted: 10 April 1997. area (Sherbrooke, 1981; Stebbins, 1985). The first problem was to determine what criteria have been used to separate and diagnose the recognized subspecies of Phrynosoma coronatum. Table 1 pre- sents the characteristics used by previous authors to Journal o Hqetology, Vol. 31, No. 3, pp. 434436, 1997 characterize the subspecies. The named populations Copyright 1997 Society for the Study of Amphibians and Reptiles are presented in Table 1 in a north to south order with l? cerroense placed last. It is clear from Table 1 that none of these characteristics appear to be very dis- Status of the Subspecies of the Coast tinctive. The number of enlarged gular scale rows is Homed Lizard, Phrynosoma coronatum 3 for all populations, the number of temporal spines is 5 or 4 + 1 = 5 for all populations and the other BAYARDH. BRATTSTROM,Department of Biology, Califor- characters are either vague, variable, or poorly defined nia State University, P.O. Box 6850, Fullerton, California, (Postrictal scale, projection of temporal spines, and the USA. location of the subrictal scale in relation to the chin shield). I then examined a large number of Phynosoma It is critical for biological, legal, and political rea- coronatum from the collections of the San Diego Nat- sons, to know the exact taxonomic status of a species ural History Museum of the named subspecies (P c.