Thermoregulation in free-ranging Nycteris thebaica (Nycteridae) during winter : no evidence of torpor

摘要

Bats are among the most heterothermic mammals, with nearly all species investigated under free-rangingconditions to date exhibiting some degree of daily torpor and/or hibernation. We investigated thermoregulationduring late winter by seven Nycteris thebaica in a warm, semi-arid habitat in northern SouthAfrica, using temperature-sensitive transmitters to measure skin temperature (Tskin). Unexpectedly, wefound no evidence for any expression of daily torpor or hibernation based on a total of 86 days of datafrom 7 bats (one male and six females), despite air temperatures as low as∼10 ◦C. Instead, daytime Tskinwas distributed unimodally with most values in the 33–35 ◦C range, and a minimum Tskin of 28.4 ◦C at aroost temperature of 24.6 ◦C. There are several possible reasons why N. thebaica may avoid torpor, includingpredation in roosts, and the long nightly foraging periods of this species compared to many others.