Dry-Season Distribution and Ecology of Carettochelys-Insculpta (Chelonia, Carettochelydidae) in Kakadu-National-Park, Northern Australia

Abstract

Carettochelys insculpta is widely distributed (though not necessarily abundant) in Kakadu National Park during the dry season, occupying permanent billabongs from the black-soil plains to the base of the escarpment. High population densities were found in the upper reaches of the South Alligator drainage (33.8 turtles ha-1; 227.4 kg ha-1) and are interpreted as dry-season concentrations of turtles that would occupy a much wider range in the wet season. C. insculpta nest in clean, fine sand adjacent to water from mid July to early November. About 15 hard-shelled spherical eggs were laid in a shallow chamber (maximum depth 18-21 cm) between 1.0 and 3.7 m from water, with the height above water ranging from 0.4 to 0.7 m. The nests suffered heavy predation from varanid lizards. The turtles are general omnivores that draw upon a wide variety of food, including algae, aquatic macrophytes, fruits, seeds and leaves of riparian vegetation, aquatic macroinvertebrates, and carrion. Its catholic tastes provide great scope for opportunism, and its diet varies greatly in accordance with the foods available from locality to locality. The ecological basis for the restricted global distribution of C. insculpta is unclear since the species appears to have very broad habitat requirements.