frills, those living between the river and the Carpentarian Gap have orange frills, and those east of the gap have yellow to white frills. New Guinean frilled lizards are yellow-frilled. The more colourful frills have white patches which may add to the display. Colouration is mainly created by carotenoids and pteridine pigments; lizards with red and orange frills have more carotenoids than those with yellow and white frills, the latter two are also lacking in pteridines. Yellow colouration has been linked to higher steroid hormones. Among western lizards, the amount of red or orange colouring correlates with success in display competitions between males of similar size. Distribution and habitat The frilled lizard inhabits northern Australia and southern New Guinea. Its Australian range stretches from the Kimberley region of Western Australia east though the Top End of the Northern Territory to Queensland's Cape York Peninsula and nearby islands of Muralug, Badu, and Moa, and south to Brisbane. In New Guinea, it lives in the Trans-Fly ecosystem on both the Papua New Guinean and Indonesian sides of the island. The species mainly inhabits savannahs and sclerophyll woodlands. It prefers highly elevated areas with good soil drainage and a greater variety of tree species, mostly Eucalyptus species, and avoids lower plains with mostly Melaleuca and Pandanus trees. Frilled lizards also prefer areas with less vegetation on the ground, as they can then better spot prey from above. Behaviour and ecology The frilled lizard is a diurnal (daytime) and arboreal species, spending over 90% each day up in the trees. It spends as little time on the ground as possible, mostly to feed, interact socially, or to travel to a new tree. Males move around more, per day on average versus for females at Kakadu National Park. In the same area, male lizards were found to have an average home range of during the dry season and during the wet season; females used and for the wet and dry seasons respectively. Male lizards assert their boundaries with frill displays. Frilled lizards are capable of moving bipedally and do so while hunting or to escape from predators. To keep balanced, they lean their heads far back enough, so it lines up behind the tail base. These lizards are more active during the wet season, when they select smaller trees and are more commonly seen near the ground; during the dry season, they use larger trees