The Ecology of the Western Swamp Tortoise Pseudemydura Umbrina (Testudines: Chelidae).

Abstract

Western swamp tortoise (Pseudemydura umbrina) was rediscovered in Western Australia in 1954. It is a relict species of a monotypic genus, of very restricted range and specialized habitat. Population was estimated to be 13 to 45 and decreasing at 1 of its 2 native reserves and to be 10 to 45 and static at the other reserve. It does not use permanent water, but lives and feeds in ephemeral winter swamps and spends the other 6 to 9 months of the year in refuges in leaf litter, under fallen branches or in holes in the ground, in contact with the soil. The tortoise is carnivorous and in the wild takes only live aquatic organisms. Captive adults will not take meat until they have starved for many months. Stomach of 1 female (Edward, pers. commun.) had aquatic crustaceans, chiefly Eulimnadia sp., with insects and insect larvae, mainly Coleoptera and Diptera. Study of faeces confirmed that observation had shown that small tadpoles and an aquatic earthworm (Eodrilus cornigravei) were eaten also. Reproduction, growth, activity relative to body and water temperature, and desiccation rate, were noted. One adult female tortoise was eaten by a fox. Foxes and bandicoots (Isoodon obesulus) eat eggs of other tortoises and would eat those of P. umbrina. Hatchlings may be eaten by large wading birds such as straw-necked ibis (Threskiornis spinicollis) and white-faced heron (Notophoyx novaehollandiae).