Flight rapidly modulates body temperature in freely behaving bats

Background: Bats are remarkable in their dynamic control over body temperature, showing both hypothermia with torpor and hyperthermia during flight. Despite considerable research in understanding bats’ thermoregulation mechanisms, knowledge on the relationship between flight and body temperature in bats remains limited, possibly due to technological restraints. Results: We used onboard dataloggers including a temperature sensor and an inertial sensor (accelerometers) and continuously recorded the flight behavior and skin temperature (T_sk) subcutaneously of a perch-hunting bat, Hipposideros armiger, both in the laboratory and in the field. We provide evidence that flight increases the body temperature of bats. The median of the maximum increase in the T_sk caused by flight bouts was 3.4 °C (between 1.9 and 5.3 °C for different individuals) in the laboratory. The maximum T_sk for the bats was narrowly centered around 40 °C (between 38.5 and 40.9 °C). Moreover, we found that the faster the T_sk rises, the greater the maximum increase in T_sk. Interestingly, bats can slow down the T_sk rises with intermittent fights, during which they perch after brief flight bouts to allow the body temperature to drop rapidly. Similar data were collected from field recordings in free-ranging bats. Conclusions: We suggest that perch-hunting behavior observed in approximately 200 species of bats that results in intermittent flights may function as a thermoregulatory strategy, in addition to optimizing energy efficiency as demonstrated by previous studies.