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

Almost all studies on daily torpor in mammals have been conducted in the la boratory under constant environmental conditions. We investigated torpor an d activity patterns in free-ranging sugar gliders (Petaurus breviceps, 100 g) using temperature telemetry and compared field data with published infor mation obtained in the laboratory. Body and/or skin temperature and activit y patterns of 12 sugar gliders were monitored from autumn to spring. Health y sugar gliders were active between sunset and sunrise, but on cold or rain y nights activity was substantially reduced. Animals in poor condition occa sionally foraged during the day. Eleven gliders were monitored for 8-171 da ys 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 fre quency 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 degrees C. Torpor was thus much deeper, longer and more frequent than in laborator y 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 re gularly during adverse weather. This Suggests that minimisation of energy l oss by the use of torpor in sugar gliders is pivotal for their survival in the wild.