Habitats, diets, and sympatry in snakes: a study from Australia

Abstract

Six species of elapid snakes were studied in a highlands region of eastern Australia. Major results were as follows. (1) These snakes are opportunistic feeders, relatively unselective with respect to prey type or prey size. (2) Despite this unselective feeding, over 60% of the diet (by weight) in all species consists of lizards and frogs. Published data show a preponderance of these prey types in Australian snakes as a whole, and I suggest that this is due to the scarcity of other potential prey items (especially small mammals and freshwater fish) in Australia. (3) Sympatry is less common in the elapids studied than among North American snakes in comparable climatic regions. I attribute the scarcity of sympatry among the Australian snakes to the restricted number of prey types available. This argument is supported by previous empirical work which suggests that prey species diversity determines snake species diversity. Observed prey-size differences between sympatric elapid species are consistent with the interpretation of interspecific competitive exclusion.