Ecological Physiology and Thermal Energetics of Two Dasyurid Marsupials

Abstract

The survival conditions facing animals that live in xeric environments are challenging, owing to varying food supply and large daily ambient temperature fluctuations. This is especially true for small endotherms since they show physiological and morphological characteristics which make them more sensitive to these conditions such as a relatively high metabolic rate and a greater heat exchange with the environment due to their large surface-to-volume ratio when compared to larger species. Therefore, the survival tactics of small mammals in this unforgiving habitat are of special interest. Studies investigating these strategies in free-ranging individuals are scant. My thesis addresses this paucity of knowledge by providing a combination of field studies and laboratory work focussing on the ecological physiology and thermal energetics of two small dasyurid marsupials inhabiting the arid zone of Australia. I investigated several energetic and ecophysiological aspects of the fat-tailed dunnart (Sminthopsis crassicaudata) and Giles’ planigale (Planigale gilesi), including body temperature regulation, metabolism, behavioural thermoregulation, water economy, ventilation, temporal organisation of activity, and microhabitat use.