Energy Expenditure, Water Flux, and Activity Budgets of Female Swamp Antechinuses in Contrasting Habitats

Island mammals often differ behaviorally, demographically, and morphologically from their mainland conspecifics. A comparison of the water flux (WF, ml/day), daily energy expenditure (DEE, kJ/day), activity budgets, body mass, and diets of female swamp antechinuses (Antechinus minimus maritimus) from island and mainland habitats was undertaken to determine whether features associated with the island habitat influenced their physiological ecology. WF differed significantly between the 2 populations, with mainland animals having a WF 36% greater than island animals. However, there was no significant difference in DEE between individuals in different habitats (island versus mainland), although they exhibited markedly divergent behavioral patterns. Differences in diet and availability of free water for drinking may have caused the divergence in the WF values between mainland and island individuals. Although energy requirements play a key role in the spatial ecology of small mammals, other factors such as social interactions could cause observed differences in spatial organization between female A. minimus on the island and mainland.