Temperature regulation in subtropical tree bats.

1. Rate of metabolism and temperature regulation were studied in five species of subtropical tree bats (Lasiurus seminolus, L. borealis, L. intermedius, L. cinereus and Nycticeius humeralis). 2. All species showed two states while resting below thermal neutrality: normothermia and torpor. Below 0-5 degrees C, bats in torpor maintained an intermediate body temperature. 3. Basal rate of metabolism was lower than expected on the basis of body mass (44-78%) and average body temperature in the normothermic state ranged between 32.5 and 35.7 degrees C. 4. Lasiurines have a high thermogenic capacity. 5. The metabolic and thermoregulatory traits studied in tree bats are generally similar to those of non-tropical bats roosting in caves and buildings.