(Tribolonotus gracilis)
Family: Skinks (Scincidae)
Order: Squamates or Scaly Reptiles (Squamata)
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Red-eyed Crocodile Skink
(Tribolonotus gracilis) Family: Skinks (Scincidae) Order: Squamates or Scaly Reptiles (Squamata) |
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Other names: Casque-headed Skink, Helmet Skink, Spiny-tailed Skink, "Bush Crocodile". Size: 15-20 cm. Weight 40-50 g. Distribution: Northern New Guinea. Habitat: Rainforests, usually near water. It has also adapted to living in coconut plantations, where it shelters under piles of husks. Occasionally enters human-populated areas. Crocodile skinks are accomplished diggers, creating complicated underground tunnel systems in the moist jungle soil. Food: Mainly insects, but also worms, slugs, and even small mammals, such as young mice. Reproduction: Reaches maturity at 3-4 years (males sooner than females). A yellowish-orange marking under the throat appears when the skink is mature. Reproduces throughout the year. About 5 weeks after mating, a single egg measuring about 30x13 mm is laid (the female has only got one ovary). She will guard the egg by curling up around it. After 40-90 days the egg hatches, at about which time a second egg is laid. A female may lay up to 10 eggs per year. The hatchling measures about 6.5 cm, and will often climb the backs of both the female and the male. Otherwise, the male does not participate in the parental care. This behaviour is also known from the Solomon Islands Giant Skink. Mother-child family groups have also been observed. After about 6 months, the youngs develop the adult coloration. Activity and behaviour: Mostly crepuscular and nocturnal. They are rarely observed during daytime in the wild, but experiences with captive animals indicate that they may be partly diurnal. Both sexes are very territorial, and males may battle other males for females. Enemies and defense: Inoffensive, but will emit a strident chirping sound when threatened. Along with the vocalization, the skink will hold its body and tail off the ground in a rigid posture. This makes the crocodile skinks among the few lizards, apart from the geckos, which are able to vocalize when distressed. As a last resort, the crocodile skinks are also known to occasionally "freeze" in order to appear dead. Longevity: May live for up to 10 years. Sexual differences: Males are considerably longer than females, have larger helmets and darker, yellowish-brown undersides, as opposed to the females' lighter, cream-coloured bellies. Only males have bluish-white raised pores on the 3rd and 4th toes of their hind feet. In the middle of the male's belly, the scales are larger and smoother than other scales. The function of this so-called "belly button" is unknown, but may be related to marking territory. Females lack this characteristic. Moreover, males have louder calls than females. Status: Generally not an abundant species, but this may in part be explained by its secretive nature. References: Adler, G.H.; Austin, C.C.; Dudley, R. 1995. Dispersal and speciation of skinks among archipelagos in the tropical Pacific Ocean. Evolutionary Ecology 9(5): 529-541. Allison, A. 1982. Distribution and ecology of New Guinea lizards. Monographiae Biologicae 42(2): 803-813. Allison, A. 2007. Herpetofauna of Papua. pp. 564-616. In: Marshall, A.J. & Beehler, B.M. (eds.). The ecology of Papua. Part 1. Periplus Editions, Singapore. pp. 1-749. Charlier, P. 1999. Haltung und Nachzucht des Neuguinea-"Buschkrokodils" Tribolonotus gracilis. Elaphe 7(3): 23-24. Cogger, H.G. 1972. A new scincid lizard of the genus Tribolonotus from Manus Island, New Guinea. Zoologische Mededelingen (Leiden) 47(16): 202-210. Dost, U. 1999. Tribolonotus gracilis Buschkrokodil. Reptilia (D) 4(6)(20): 47-50. Evers, M. 2006. Das Buschkrokodil - heimliche Schönheit im Terrarium. Reptilia (D) 11(2): 55-60. (Nr 58. Foufopouklos, J.; Richards, S. 2007. Amphibians and reptiles of New Britain Island, Papua New Guinea: diversity and conservation status. Hamadryad 31(2): 176-201. Greer, A.E.; Parker, F. 1968. A new species of Tribolonotus (Lacertilia: Scincidae) from Bougainville and Buka, Solomon Islands, with comments on the biology of the genus. Breviora 291: 1-23. Hartdegen, R.W.; Russell, M.J.; Young, B.; Reams, R.D. 2001. Vocalization of the crocodile skink, Tribolonotus gracilis (de Rooy, 1909), and evidence of parental care. Contemporary Herpetology 2 Hauschild, A.; Gassner, P. 1995. Skinke im Terrarium. Landbuch, Hannover. 197 pp. Li Vigni, F. 2009. Tribolonotus gracilis. A peculiar 'crocodile' in the terrarium. Reptilia (GB) 62: 57-61. McCoy, M. 2006. Reptiles of the Solomon Islands. Pensoft, Sofia & Moscow. 212 pp. Meyer, J. 2002. Einige Bemerkungen zur Haltung und Nachzucht von Helmskinken der Art Tribolonotus gracilis (De Rooij, 1909). Herpetofauna (Weinstadt) 24(139): 28-34. Mys, B. 1988. The zoogeography of the scincid lizards from North Papua New Guinea (Reptilia: Scincidae). I. The distribution of the species. Bulletin de l'Institut Royal des Sciences Naturelles de Belgique Biologie 58: 127-183. O'Shea, M. 1991. The reptiles of Papua New Guinea. British Herpetological Society Bulletin 37: 15-32. O'Shea, M. 1994. The herpetofauna of coconut husk piles on Kar Kar Island, Madang Province, Papua New Guinea. The initial surveys (with a discussion of the herpetofauna of Kar Kar in comparison with that of the neighbouring Madang mainland). ASRA (Association for the Study of Reptilia and Amphibia) Journal 1994: 51-72. Pernetta, J.C. 1989. Sexual dimorphism in the scincid lizard Tribolonotus brongersmai from Manus Island, Papua New Guinea. Science in New Guinea 15(3): 140-144. Peters, U. 1970. Tribolonotus gracilis im Terrarium. DATZ (Die Aquarien- und Terrarien-Zeitschrift) 23(1): 29-30. Peters, U. 1976. Das Echsenporträt: Der Helmkopfskink. Aquarien Magazin 10(6): 263. Reams, R.D.; Urbanek, D.A. 2001. Tribolonotus gracilis (crocodile skink). Maternal care. Herpetological Review 32(4): 259-260. Reeder, T.W. 2003. A phylogeny of the Australian Sphenomorphus group (Scincidae: Squamata) and the phylogenetic placement of the crocodile skinks (Tribolonotus): Bayesian approaches to assessing congruence and obtaining confidence in maximum likelihood inferred relationships. Molecular Phylogenetics and Evolution 27(3): 384-397. Rooij, N. de 1915. The reptiles of the Indo-Australian Archipelago. Vol. 1. Lacertilia, Chelonia, Emydosauria. E.J. Brill, Leiden. 384 pp. Russell, M.J. 1996. Notes on the natural history, captive husbandry, and reproduction of crocodile skinks (Tribolonotus gracilis) at the Dallas Zoo. pp. 69-74. In: Strimple, P.D. (ed.). Advances in herpetoculture. Special publications of the International Herpetological Symposium 1: 1-167. Russell, M.J. 1997. Crocodile skinks. Reptiles Magazine 5(12): 10-17. Russell, M.J. 1997. Husbandry notes on a juvenile crocodile skink, Tribolonotus gracilis. Bulletin of the Association of Reptilian and Amphibian Veterinarians 7(4): 9. Tufvesson, M. 2001. Hold og opdræt af Tribolonotus gracilis, rødøjet krokodilleskink. [Captive care and breeding of Tribolonotus gracilis, the red-eyed crocodile skink.] (In Danish, English summary). Nordisk Herpetologisk Forening 44(4): 132-137. Whitaker, R.; Whitaker, Z.; Mills, D. 1982. Reptiles of Papua New Guinea. Wildlife in Papua New Guinea 82(2): 1-53. Zweifel, R.G. 1966. A new lizard of the genus Tribolonotus (Scincidae) from New Britain. American Museum Novitates 2264: 1-12. Zweifel, R.G. 1980. Results of the Archbold Expeditions, No. 103. Frogs and lizards from the Huon Peninsula, Papua New Guinea. Bulletin of the American Museum of Natural History 165(5): 390-434. Text & layout: Rune Midtgaard |
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