The frill-necked lizard (Chlamydosaurus kingii) is so called because of the large ruff of skin which usually lies folded back against its head and neck. The frill is supported by long spines of cartilige, and when the lizard is frightened, it gapes its mouth showing a bright pink or yellow lining, and the frill flares out, displaying bright orange and red scales. The frill may also aid in thermoregulation.
Frillnecks are usually grey, brown or reddish-brown. They may grow up to one metre in total length. They often walk bipedally when on the ground. When frightened they begin to run on all-fours and then accelerate onto the hind-legs (Shine and Lambeck 1989).
The lizard is found in southern New Guinea, the Kimberley and across northern Australia. It primarily inhabits savanna woodlands, but may also be found in tropical to warm temperate forests, and where there is an open scrub or tussock grass understorey. It is semi-arboreal, and hunts in the trees for small arthropods (including caterpillars and cicadas), and on the ground for ants and termites, spiders, or small vertebrates (e.g. other lizards).
During breeding season (early wet season, September-October), adult males fight for mates, displaying their frills and biting each other. One to two clutches of 4-23 eggs are laid in the early to mid-wet (November-February) in a nest 5-20 cm below ground, and usually in sunny areas (Shine and Lambeck 1989). Incubation takes two to three months. Sex is partly temperature determined, with extreme temperatures producing exclusively females, and intermediate temperatures (29-35C) producing equal numbers of males and females (Harlow and Shine 1998).
The lizards are less active during the dry season (April-August) (Shine and Lambeck 1989).
Males are significantly larger than females both as juveniles and when mature (Harlow and Shine 1998).
The only reported predators are Morelia sp. (Bedford 1995).
References
Bedford, G. S. 1995. Anti-predator tactics from the Frilled Neck Lizard Chlamydosaurus kingii. Journal of the Victorian Herpetelogical Society 6(3): 120-130.
Harlow, P. S. and R. Shine. 1998. Temperature dependent sex-determination in the frillneck lizard Chlamydosaurus kingii (Agamidae). Herpetologica 55(2): 205-212.
Shine, R. and R. Lambeck. 1989. Ecology of frillneck lizards, Chlamydosaurus kingii (Agamidae) in tropical Australia. Australian Wildlife Research 16: 491-500.
