Energy Requirements and Water Turnover in Free-Living Leadbeater's Possums, Gymnobelideus Leadbeateri (Marsupialia: Petauridae).

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Abstract
The field metabolic rate (FMC) and water turnover rate of free-living Leadbeater's possums (Gymnobelideus leadbeateri) was estimated by means of doubly labelled water. This information was combined with field estimations of daily activity, and laboratory estimations of basal metabolism, to formulate daily energy budget. Possums emerged from their nest at dusk, but returned to them periodically throughout the night. An estimated 17.7 h of the day was spent in the nest at a total energy cost of 29 kJ (13% of FMR). Of the total 197 kJ expended during the 6.3-h active period, 10 kJ (4% of FMR) was attributable to maintenance costs, 23 kJ (10% of FMR) to thermoregulation, and 165 kJ (73% of FMR) to activity and specific dynamic action. The apparently high cost of activity is consistent with the dispersed nature of the possums' food supply and their well developed, territorial social system. Water turnover rates varied with season, sex and rainfall. Water shortage at certain periods of year may restrict exploitation of some food items (dehydrated plant exudates).