Torpor and activity patterns in free-ranging sugar gliders Petaurus breviceps (Marsupialia)

Abstract

Almost all studies on daily torpor in mammals have been conducted in the laboratory under constant environmental conditions. We investigated torpor and activity patterns in free-ranging sugar gliders (Petaurus breviceps, 100 g) using temperature telemetry and compared field data with published information obtained in the laboratory. Body and/or skin temperature and activity patterns of 12 sugar gliders were monitored from autumn to spring. Healthy sugar gliders were active between sunset and sunrise, but on cold or rainy nights activity was substantially reduced. Animals in poor condition occasionally foraged during the day. Eleven gliders were monitored for 8-171 days and all of these entered daily torpor. Torpor was observed on 103 days (17% of observation days), usually occurred on rainy or cold nights, and frequency of torpor changed with season. Torpor bouts lasted between 2 and 23 h (average 13 h) and the body temperature fell to a minimum of 10.4°C. Torpor was thus much deeper, longer and more frequent than in laboratory studies on the same species. Our study shows that cold or wet conditions curtail foraging in wild sugar gliders and that they employ daily torpor regularly during adverse weather. This suggests that minimisation of energy loss by the use of torpor in sugar gliders is pivotal for their survival in the wild.

Coping with chaos: unpredictable food supplies intensify torpor use in an arid-zone marsupial, the fat-tailed dunnart (Sminthopsis crassicaudata)

“…capabilities (Körtner and Geiser 2000;Christian and Gesier 2007), particularly for dealing the vagaries of weather that drive food availability. The wide distribution of the fat-tailed dunnart in Australia suggests they are well adapted to the challenges of resource scarcity (Morton 1982;Frey 1991).…”

Hibernation and daily torpor in Australian mammals

“…Daily torpor, interrupted by arousal around dusk, often was observed over a sequence of several days, torpor bouts lasted for up to 23 hours (average 13 hours), and T b fell as low as 10.4°C (Körtner and Geiser 2000b;Christian and Geiser 2007;Geiser et al 2007). In winter (May to October), free-ranging sugar gliders entered torpor on about 17% of observation days in a wet year and torpor was common during cool, wet nights (Körtner and Geiser 2000b). However, in dry years in the same area, torpor frequency can be considerably lower (Christian and Geiser 2007).…”

An Energy‐Based Body Temperature Threshold between Torpor and Normothermia for Small Mammals

“…Confinement in a metabolic chamber is not a natural circumstance for any species, so MR data, while valuable, are limited in terms of what they reveal about use of torpor in the wild (Willis and Cooper, forthcoming). A growing number of studies use temperature-sensitive transmitters or dataloggers to record T b or skin temperature (T sk ) in freeliving animals (Körtner and Geiser 2000;Lausen and Barclay 2003;Turbill et al 2003;Dietz and Kalko 2005;Munro et al 2005;Solick and Barclay 2006;Turbill 2006) or under seminatural conditions in laboratory enclosures (Song et al 1998a;Schmid 2000;Cooper and Withers 2004;Willis et al 2005a). As in the laboratory, these studies often aim to quantify temporal patterns and magnitude of torpor bouts because these variables affect energy balance with implications for reproductive fitness.…”