View article

Bats hibernate to cope with low ambient temperatures (T_a) and low food availability during winter. However, hibernation is frequently interrupted by arousals, when bats increase body temperature (T_b) and metabolic rate (MR) to normothermic levels. Arousals account for more than 85% of a bat’s winter energy expenditure. This has been associated with variation in T_b, T_a or both, leading to a single testable prediction, i.e. that torpor bout length (TBL) is negatively correlated with T_a and T_b. T_a and T_b were both found to be correlated with TBL, but correlations alone cannot establish a causal link between arousal and T_b or T_a. Because hydration state has also been implicated in arousals from hibernation, we hypothesized that water loss during hibernation creates the need in bats to arouse to drink. We measured TBL of bats (Pipistrellus kuhlii) at the same T_a but under different conditions of humidity, and found …