Thermoregulation and torpor in the Kultarr,Antechinomys laniger (Marsupialia: Dasyuridae)

Summary

• 1. Body temperatures (T _b), rates of oxygen consumption ($\dot V_{O_2 }$) and the loss in body mass of the small insectivorous dasyurid marsupialAntechinomys laniger were determined at different ambient temperatures (T _a).

• 2. Most animals entered torpor belowT _a 27°C when food was witheld. Spontaneous torpor was observed frequently atT _a 19 and 12.5°C.

• 3. An increase in$\dot V_{O_2 }$ and ΔT (T _b-T _a) was observed during torpor below aT _a of about 11°C. The lowest individualT _b measured was 11.0°C.

• 4. The linear increase in$\dot V_{O_2 }$ during torpor belowT _a 11°C was parallel to theT _a related increased in metabolism of normothermic resting, active, and arousing animals.

• 5. Torpor lasted between 2 and 16 h and the longest durations were observed atT _a 13–20°C; below and above this temperature range torpor bouts were shorter.

• 6. The lowest relative weight loss was observed at theT _a of the longest torpor bouts and lowest metabolism during torpor.

• 7. Both the time of the activity peaks and onset of torpor were dependent onT _a and were observed later in the night at higherT _a. Torpor commenced before the onset of light.

• 8. Arousal rates were rapid and the arousal times increased exponentially with decreasing T_a.