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these taxa are separate biological (Mengden, MIRTSCHIN,P. J. 1982. Seasonal colour changes in 1985). Pseudonajainframacula and P. nuchalis are both the , Oxyuranus microlepidota(Mc- large and highly venomous species; consequently, Coy). Herpetofauna 14:97-99. correct identification of these may be impor- NORRIS,K. S. 1967. Color adaptation in desert rep- tant for medical reasons. tiles and its thermal relationships. In W. W. Mil- nuchalis is a composite taxon which ex- stead (ed.), Ecology: A Symposium, pp. 162- hibits great variation in color and pattern (Gillam, 299. Univ. Missouri Press, Columbia. some of which reflect 1979), electrophoretic and chro- PORTER,W. P. 1967. Solar radiation through the liv- mosomal variation (Mengden, 1985). Seasonal color ing body walls of vertebrates with emphasis on changes must now be taken into account when de- desert . Ecol. Monogr. 37:273-296. scribing the color variation among populations cur- RAHN, J. 1941. The pituitary regulation of melano- rently identifiable as P. nuchalis.All of the P. nuchalis phores in the rattlesnake. Biol. Bull. 80:228-237. in which seasonal color changes were observed by REHAK,I. 1987. Color change in the Tropidophis Banks (1981), and those quantified here, belonged to feicki (Reptilia: : Tropidophidae). Vestnk the 'southern' group of taxa recognized by Mengden Ceskoslovenske Spolecnosti Zoologicke 51:300- (1985). It is unclear whether other taxa within the P. 303. nuchaliscomplex exhibit seasonal color changes. SHINE,R. 1991. Australian Snakes: A Natural His- Reed Books, Chatswood. 224 Acknowledgments.-P. Fennell, P. Hudson, P. Mirt- tory. pp. SOKAL, R. R., AND F. J. ROHLF. 1981. 2nd schin and H. Nygren helped maintain the snakes at Biometry, ed. W. H. Freeman, San Francisco. 569 the Whyalla Fauna Park. The spectrophotometer was pp. SWEET,S. S. 1985. variation, loaned to me by R. Comments from J. Cova- Geographic convergent Hope. and in snakes cevich, R. Shine and two anonymous reviewers im- crypsis, mimicry gopher (Pituophis and western rattlesnakes proved the manuscript. J. Cornish provided photo- melanoleucus) (Crotalus viridis). J. 19:55-67. graphs for Fig. 3. Herpetol. WAITE,E. R. 1925. Field notes on some Australian and a batrachian. LITERATURECITED reptiles Rec. S. Aust. Mus. 3:17- 32. ANDM. E. HADLEY.1973. Chromat- BAGNARA,J. Y., WARING,H. 1963. Color Change Mechanisms of Cold- ophores and Color Change: Comparative Physi- blooded Vertebrates. Academic Press, New York. of ology Pigmentation. Prentice-Hall, En- 266 pp. New 202 glewood Cliffs, Jersey. pp. ZWEIFEL,R. G. 1981. Genetics of color pattern poly- C. B. 1981. Notes on seasonal colour BANKS, changes morphism in the California kingsnake. J. Heredity on a western brown snake. Herpetofauna 13:29- 72:238-244. 30. H. AND E. BECHTEL.1985. Genetics of BECHTEL, B., Accepted: 24 October 1993. color mutations in the snake, Elapheobsoleta. J. He- redity 76:7-11. BENFORD,F., G. P. LLOYD,AND S. SCHARZ.1948. Co- efficients of reflection of magnesium oxide and magnesium carbonate. J. Optical Soc. Amer. 38: 445-447. Vol. No. 1994 CAMIN,J. H., AND P. R. EHRLICH. 1958. Natural se- Journalof Herpetology, 28, 1, pp. 112-114, J. Copyright 1994 Society for the Study of Amphibians and Reptiles lection in water snakes (Natrix sipedon L.) on is- lands in Lake Erie. Evolution 12:504-511. GILLAM,M. W. 1979. The genus Pseudonaja (Ser- Impact of Artificial Lighting on the pentes: ) in the Northern Territory. Ter- ritory Parks and Wildlife Commiss. Res. Bull. No. Seaward Orientation of Hatchling 1. 28 pp. Loggerhead Turtles HADLEY,M. E., AND J. M. GOLDMAN. 1969. Physio- ANNEPETERS AND KOEN F. logical color changes in reptiles. Amer. Zool. 9:489- J. VERHOEVEN,Department 504. of Animal Ecology, University of Nijmegen, Toernooiveld, HEDGES,S. B., C. A. HASS,AND T. K. MAUGAL.1989. 6525 ED, Nijmegen, The Netherlands. Physiological color change in snakes. J. Herpetol. 23:450-455. Under natural conditions marine turtle hatchlings KING,R. B. 1987. Color pattern polymorphism in the emerge from their nest primarily at night and im- Lake Erie water snake, Nerodia sipedon insularum. mediately crawl seaward. They are guided by the op- Evolution 41:241-255. tical cues provided by the relatively bright horizon . 1988. Polymorphic populations of the garter over the ocean (as reviewed by Mrosovsky and Kings- snake Thamnophissirtalis near Lake Erie. Herpe- mill, 1985). Experiments have demonstrated the rel- tologica 44:451-458. ative effects of light intensity and color on hatchling MENGDEN, G. A. 1985. A chromosomal and electro- orientation (Mrosovsky and Kingsmill, 1985; With- phoretic analysis of the genus Pseudonaja. In G. erington and Bjorndal, 1991). One implication of the Grigg, R. Shine, and H. Ehmann (eds.), Biology of dependence on photic cues is the possible disturbing Australasian Frogs and Reptiles, pp. 193-208. R. effect of photopollution. The presence of artificial Zool. Soc. New South Wales, Sydney. lights at a nesting beach can cause mortality in hatch- 0046769

NOTES 113

N

A B 3 3

2 (37X%) 4 2(24X7% ) 4

1 1

seaside * nest 10m I

FIG.2. Distribution of Caretta hatchling tracks (as %of total). A. In area A directly in front of the holiday village (cf. Fig. 1) (N = 330 tracks; 6 nests). B. In area B, SE of the holiday village (N = 490; 17 nests). FIG.1. Map of the western side of the G6ksu delta, Turkey, showing the main sources of artificial light. A, B. Caretta caretta nesting zone. facing inland, and quarter four facing roughly SE (cf. Fig. 2). At a radius approximately 10 m from the nest all outgoing tracks per quarter were counted. To es- lings by directing them away from the sea. Anecdotal tablish the efficiency of the track-count, all nests were accounts of such disorientation have been reported excavated. Numbers of emerged hatchlings were de- for loggerhead turtles (Carettacaretta; McFarlane, 1963), termined by counting empty eggshells and hatch- green turtles (Chelonia mydas; Mortimer, 1979; van lings left in the nest column. For statistical analyses, Rhijn, 1979), and hawksbill turtles (Eretmochelysim- the limited number of observations sometimes ne- bricata; Philibosian, 1976). The present study is an cessitated us to group adjacent clutches, considering attempt to quantify the impact of artificial lighting at hatchlings within one group independent statistical a nesting beach with a large source of photopollution units. (human settlement) nearby. Our aim was to investi- For 23 nests, uniformly scattered over the six km gate to what extent Caretta hatchlings failed to de- of the nesting zone (X2= 4.4; df = 5: P > 0.05), a total termine a correct seaward orientation after emerging number of 820 Carettahatchling tracks were counted, from their nest. which represented a mean of 75% of all possible The study was conducted on the western side of hatchling tracks per nest. An unusually low emer- the Goksu delta, 36017'N-33059'E, south of the town gence rate resulted in this low average number of of Silifke on the Turkish Mediterranean coast. To the tracks per nest (Peters et al., 1994). Tracks were mostly west, the area is bounded by the mountainous coast- missed because of occasional strong winds and local line enclosing Tasucu Bay, the village of Tasucu, and unsuitable sand types. Overlapping tracks probably a large paper factory complex (Fig. 1). In the north- caused little bias since departures with high concen- westernmost 1.5 km of the study area, the houses of trations of tracks in the same direction were rare. a holiday village are built directly behind the beach. Thus, it seems a fair assumption that our track counts The nesting zone of the beach (total +6 km) is quite provide a reliable reflection of the actual orientation uniform. After an open, slightly sloping stretch of of the hatchlings. Of all tracks counted only 37%were 15-25 m, the beach turns into small, flat dunes with in the first (sea-facing) quarter. Directly in front of dispersed low shrubs. the holiday village (area A), distribution of tracks over In June and July 1992 the beach was patrolled every the quarters differed significantly X2 = 66; df = 3; P other day and nests were marked. Throughout the < 0.01) from distribution of tracks in area B, south- entire emergence season (August and September), the east of the holiday village (Fig. 2). In area A, only beach was patrolled every morning. After emergence 21% of the hatchlings showed a correct seaward ori- of hatchlings, number and orientation of hatchling entation (quarter 1). Here, the major part of the hatch- tracks were quantified by dividing the area around lings proceeded toward individual street lights di- the nest into four quarters: the first quarter facing the rectly behind the beach or to the very bright lights sea, quarter two facing roughly NW, quarter three of the paper factory, resulting in high numbers of 0046770

114 NOTES

tracks in quarters 2 and 3. Most of these hatchlings and support and to Lorna Brown for stimulating dis- were crushed by cars or wandered further inland. cussions. This study was supported by D.H.K.D., Tur- In area B, disorientation, although less profound, key, Van Tienhoven Stichting and Stichting Nijmeegs was still substantial; 52% of the hatchlings did not Universiteitsfonds, The Netherlands. crawl directly toward the surf (Fig. 2B). Not all dis- oriented hatchlings failed to reach the surf. Some LITERATURECITED reached the sea after hatchlings eventually crawling MCFARLANE,R. W. 1963. Disorientation of logger- several hundred meters in the dunes, but a num- large head hatchlings by artificial road lighting. Copeia ber of them perished inland. For the nests in area B, 1963:153. no correlation was found between the of percentage MORTIMER,J. A. 1979. Ascension island: British with a seaward orientation and the lunar jeop- hatchlings ardize 45 years of conservation. Mar. Turtle News- cycle, the distance of the nest to the high tide mark, lett. 10:7-8. vegetational cover near the nest, and distance to the MROSOVSKY,N., AND S. F. KINGSMILL.1985. How The disoriented were not holiday village. hatchlings turtles find the sea. Z. Tierpsychol. 67:237-256. equally distributed over quarters 2, 3, and 4, (X2 = 9.6; , A. M. GRANDAAND T. HAY. 1979. Seaward df = 2; P < The often maintained an 0.01). majority orientation of hatchling turtles: turning systems northward, inland direction, around approximately in the optic tectum. Brain Behav. Evol. 16:203-221. the between 2 and 3. dividing-line quarters Thus, PETERS,A., K. J. F. VERHOEVEN,AND H. STRIJBOSCH. showed a but deviation hatchlings slight noteworthy 1994. Hatching and emergence in the Turkish from the centre of two, which faces the com- quarter Mediterranean loggerhead turtle, Caretta caretta: bined of Tasucu, the and the lights paper factory, natural causes for egg and failure. Her- This seems to the ex- hatchling holiday village. contradictory petologica, in press. observed between perimentally positive relationship PHILIBOSIAN,R. 1976. Disorientation of hawksbill and orientation light intensity preferred (Withering- turtle imbricata, stadi- ton and but the hatchlings, Eretmochelys by Bjorndal, 1991), might result from um 1976:824. mechanism the orientation of sea lights. Copeia underlying optic VAN RHIJN,F. A. 1979. orientation in hatch- turtle Optic hatchlings. of the sea turtle, Chelonia I. Two with as a cue are lings mydas Brightness: mechanisms brightness pro- not the cue in orientation. a ini- only optic sea-finding posed: complex phototropotactic system, which Mar. Behav. 6:105-121. tiates until in different Physiol. turning brightness inputs parts VERHEIJEN,F. AND T. WILDSCHUT.1973. The et and J., J. of the eyes are balanced (Mrosovsky al., 1979), orientation of sea turtles a direction in which the area is lo- photic hatchling during system, brightest water finding behaviour. Neth. J. Sea Res. 7:53- cated instantaneously with a very large angle of ac- 67. in the horizontal and Wild- ceptance plane (Verheijen WITHERINGTON, B. E., AND K. A. BJORNDAL. 1991. In- schut, 1973). Both mechanisms can a deviation explain fluences of wavelength and intensity on hatchling from the direction toward the brightest area in a cer- sea turtle for tain situation. When are phototaxis: implications sea-finding experimental hatchlings behavior. Copeia 1991:1060-1069. placed in a circular field composed of stripes that become darker with the last and darkest progressively Accepted: 26 October 1993. stripe adjacent to the first and brightest stripe, they do not head for the brightest stripe, but deviate at an toward the and angle pale grey stripes (Verheijen Journalof Herpetology,Vol. 28, No. 1, pp. 114-117, 1994 Wildschut, 1973). This experimental condition resem- Copyright 1994 Society for the Study of Amphibians and Reptiles bles our field situation, in which the brightest area (holiday village, paper factory, Tasucu) is to the west adjacent to the mountains that enclose Tasucu bay, Sexual Dichromatism in Snakes of the darkening the skyline, while to the north-east the Genus Vipera: A Review and a New brightness is continued by the dim halo of the lights of distant Silifke (cf. Fig. 1). It seems plausible that Evolutionary Hypothesis the resemblance suffices to the ob- explain regularly RICHARD SHINE AND THOMAS MADSEN, De- served for a northward orientation. Zoology preference partment, The University of Sydney, N.S.W. 2006, Aus- In our study substantial disorientation of hatchling tralia. loggerhead turtles occurred throughout the entire nesting beach, which continued over 4 km past the The sexes differ in color in of zone of artificial lighting. In total 63% of the hatch- many species snakes, but these differences are subtle and their lings did not show a correct seaward orientation at generally selective remains obscure 10 m from the nest, but mainly oriented toward the advantage (if any) (Shine, One in which dichro- artificial light source. These figures indicate the po- 1993a). phylogenetic lineage matism and in which the of dichro- tentially disastrous effect photopollution has on the occurs, degree matism varies is in the long-term survival of this sea turtle population. among closely-related taxa, Old World viperid snakes of the genus Vipera.These Acknowledgments.-We would like to thank Henk snakes are well-suited to an analysis of the adaptive Strijbosch for his guidance and review of the paper. significance of dichromatism because they are rela- We are grateful to Vincent van den Berk, Nafiz Gilder, tively well-known ecologically. In particular, the most and Alice Carswell of D.H.K.D. for their valuable help strongly dichromatic species, V. berus,is arguably the