To bask or not to bask: Behavioural thermoregulation in two species of dasyurid, Phascogale calura and Antechinomys laniger

• Basking use and duration was measured in two native Australian marsupials.
• Both species used basking; generally kultarrs would bask longer than phascogales.
• Food availability increased basking duration and frequency in some individuals.
• Phascogales show strict nocturnal activity, while kultarrs showed diurnal activity as well.
• Basking may be an important behavioural adaptation for kultarrs and phascogales.

Torpor is an important physiological process used to reduce body temperature and thus energy needs in mammals and birds. Rewarming from torpor can be costly. In some small mammals basking is used to reduce the cost of rewarming from torpor. The use and duration of basking was measured in two native Australian marsupials, the red-tailed phascogale (Phascogale calura) and kultarr (Antechinomys laniger), using a heat rock. Animals were observed via video cameras to determine whether they used basking behaviours and whether this behaviour was affected by food availability. Both species became accustomed to the heat rock as time progressed. Absence of food increased basking duration and frequency in some individuals but not all animals. Generally kultarrs basked for longer periods than phascogales, and kultarrs would bask at all hours of the day while phascogales showed a strict nocturnal regime (1900–0700 h). The results demonstrate that basking may be an important behavioural adaptation of the kultarr; while the phascogale requires further research.