Nesting habitat of the broad-shelled turtle (Chelodina expansa)

Abstract

Turtles have persisted for over 220 million years, despite facing threats at every life-history stage. In Australia, nest predation by introduced foxes has driven severe declines in some populations. Our project quantified the nesting habitat of the endangered broad-shelled turtle (Chelodina expansa) to facilitate protection of critical nesting grounds. We determined the nesting preferences of C. expansa at five distinct wetlands on the Murray River from 2011 to 2014. We identified environmental variables associated with nest sites in different habitats and compared those at nests and non-nest sites to determine nesting preferences. Kernel density estimates were used to identify important nesting grounds. Our study has important implications for conservation of C. expansa. Habitat preferences for nest sites of C. expansa are predictable both within and across sites, with females preferring to nest ~50 m from shore (~4 m elevation), in open habitat with little vegetation. Based on these habitat preferences, kernel density estimates showed that C. expansa may select the same nesting beaches in subsequent years. Fox depredation of nests (and nesting adults) drives turtle declines in Australia, so identifying nesting areas for protection is a first step in turtle conservation.