The activity of Sand Goannas Varanus gouldii and their interaction with reintroduced Greater Stick-nest Rats Leporillus conditor

Abstract

The activity pattern of the Sand Goanna Varanus gouldii in northern South Australia was estimated by radio telemetryduring the summer months. Individuals were located within the Arid Recovery Reserve where introduced European Rabbits Oryctolagus cunniculus, Feral Cats Felis catus and European Foxes Vulpes vulpes were removed. Interaction between the re-introduced Greater Stick-nest Rat Leporillus conditor and the Sand Goanna, a potential significant predator in the absence of cats and foxes, was examined. Mean activity area for Sand Goannas was 5.9 ha (±1.0, n = 9), and their summer activity was concentrated on sand dunes rather than the adjacent inter-dunal swales. Tracks of Sand Goannas were found more often around Greater Stick-nest Rat nests than control sites. However, Sand Goanna predation on re-introduced Greater Stick-nest Rats could not be confirmed and most deaths of radio-collared Greater Stick-nest Rats coincided with a period of exceptionally high maximum temperatures and were probably due to heat and dehydration. Sand Goannas scavenged Greater Stick-nest Rat carcasses, and analysis of scats and stomach material revealed that although invertebrates were the most common prey item, mammal material (hair and bones) was present in 20% of scats.