Thermal Biology And Energentics Of Carnivorous Marsupials

Abstract

Extant carnivorous marsupials are small (4-13,000 g) and almost all are nocturnal or crepuscular and are active during the coldest part of the day. Heat loss and gain via their relative large surface area is therefore likely to be substantial and to have implications on thermal biology and energy expenditure. In this review, data on thermoenergetics in carnivorous marsupials, with an emphasis on the families Dasyuridae and Didelphidae, are summarised and compared with data on other marsupials and mammals in general. All carnivorous marsupials have low basal metabolic rates (BMR) when compared to most placental mammals, but similar BMR to those of omnivorous/herbivorous marsupials. Thermal conductances of carnivorous marsupials are similar to those of other similar-sized mammals. Carnivorous marsupials have a high metabolic scope and endogenous heat production is achieved to a large extent by shivering thermogenesis and some poorly understood non-shivering component. During exposure to heat carnivorous marsupials use predominantly panting and licking of fur and appendages for evaporative cooling. Carnivorous marsupials have relatively high field metabolic rates (FMR) and, especially in the small species, high FMR/BMR ratios. To minimise daily energy expenditure many carnivorous marsupials use communal nesting and huddling and torpor extensively and thus can lower energy expenditure substantially. While thermal biology and energetics of carnivorous marsupials generally is well known, most of the information is based on laboratory work. Thus, more fieldwork is needed to put physiological data of carnivorous marsupials into an ecological context.