The implication of small reductions in body temperature for radiant and convective heat loss in resting endothermic brown long-eared bats (Plecotus auritus)

1. 1.|Dorsal surface temperature (T_s) and rectal temperature (T_b) were measured in four captive endothermic brown long-eared bats, Plecotus auritus, resting at ambient temperatures (T_a) of 5, 15 and 25°C. 2. 2.|A heat flux model for the bats was derived and the reduction in radiant and convective heat loss associated with small reductions in T_b were predicted from thoeretical equations. 3. 3.|A drop in body temperature from the maximum (38.2°C) to the minimum (31.5°C) recorded value was estimated to produce energy savings through a reduction in gross radiant and convective heat loss of 25 and 44% of metabolic heat production at ambient temperatures of 5 and 25°C, respectively. 4. 4.|We suggest that small reductions in body temperature offer resting thermolabile bats a compromise between rapid behavioural function associated with high body temperature and low energy demand associated with torpor.