Populations of the Murray River Tortoise, Emydura (Chelodina): the Effect of Egg Predation by the Red Fox, Vulpes vulpes

Abstract

Regular inspection of tortoise nesting sites along the Murray River in South Australia showed that over 96% of eggs were taken by predators. Endemic predators accounted for less than 3% of this total. Foxes took the rest. Comparison of the age structure of the Emydura species in the Murray and Cooper Creek revealed that the populations were very different. The Murray population of Emydura rnacquarii contained a disproportionately large number of old individuals; this difference was attributed to egg losses. The same was true for Chelodina longicollis. As these old animals die recruitment of juveniles into the population will probably fall even further. As a result tortoise populations in the Murray will decline.