Antipredator behaviour of red-necked pademelons: a factor contributing to species survival?

Abstract

Australian mammals have one of the world's worst records of recent extinctions. A number of studies have demonstrated that red foxes (Vulpes vulpes) have a profound effect on the population biology of some species. However, not all species exposed to fox predation have declined. We studied the antipredator behaviour of a species that has not declined - the red-necked pademelon (Thylogale thetis), and contrasted it with previous studies on a species that has declined - the tammar wallaby (Macropus eugenii), to try to understand behavioural factors associated with survival. We focused on two antipredator behaviours: predator recognition and the way in which antipredator vigilance is influenced by the presence of conspecifics. We found that predator-naive pademelons responded to the sight of certain predators, suggesting that they had some degree of innate recognition ability. However, pademelons responded similarly to a broad range of acoustic stimuli, including dingo howls, wedge-tailed eagle calls, foot-thumps - a predator-elicited sound - and a control sound, suggesting that they did not specifically recognize predator vocalizations. Unlike a number of other macropodid marsupials, including tammars, pademelons did not modify time allocated to antipredator vigilance as group size increased. Taken together, these results suggest that red-necked pademelons independently assessed and managed their predation risk whereas tammars relied more on conspecifics to assess and manage risk. We suggest that these factors may have been important determinants of species survival. More generally, we suggest that a fundamental understanding of antipredator behaviour can enlighten conservation efforts.