Daily Torpor in the Marsupial Mouse, Sminthopsis larapinta (Spencer)

Abstract

A PERIODIC and often diurnal lowering of the body temperature has been reported in birds and bats¹, rodents belonging to six different families², and among marsupials (Eudromicia³;, Cercartetus^3,4). The associated inactive state is known as torpor to distinguish it from hibernation and aestivation, which are seasonal phenomena. Bartholomew and Cade⁵ obtained a continuous record of the temperature during entry into torpor and arousal in the little pocket mouse, Perognathus longimembris, using embedded thermocouples with detachable leads. Rectal thermocouples with leads taped to the tail have been used to measure changes in temperature during arousal in the birch mouse, Sicista betulina⁶, the ground squirrel, Citellus mohavensis⁷, the marsupial pigmy possum, Cercaërtus (= Cercartetus) nanus^3,4 and other species⁸. Tucker⁹ kept Perognathus californicus in 200 ml. glass jars fitted with thermocouples, and measured the incidence of torpor from the changes in temperature of the jars. This communication reports on torpor in the marsupial mouse, Sminthopsis larapinta (Spencer). Temperature changes during entry into torpor and arousal were measured using a thermistor fixed in the nest box.