The importance of shelter to the Quokka, Setonix brachyurus (Marsupialia), on Rottnest Island

Abstract

Quokkas aggregate about the patches of vegetation providing them with shelter. As days become hotter some quokkas cool themselves by moving from bushes that have a high heat load to those with a lesser one. Of the bushes with lower heat loads, the quokkas prefer those that are slightly hotter but which have drier atmospheres. Juveniles move to bushes with lower heat loads on more hot days than adults, and adult males move on more hot days than adult females. In the field, quokkas have a well-developed social organization in which adult males are dominant and adult females and juveniles have no social rank. Males form a linear hierarchy in which the older adults rank higher than the younger. Male quokkas defend a personal space and this defence is most marked in the vicinity of their rest sites. The social status of individual quokkas does not appear to determine the type of shelter they use on hot days. Numbers of quokkas in the study area increased when shelter was added experimentally during later summer, which shows that shelter is a limiting resource.