Torpor energetics are related to the interaction between body mass and climate in bats of the family Vespertilionidae

Torpor is an adaptive strategy that allows animals to cope with energy limitations under adverse environmental conditions. In birds and mammals, intrinsic and extrinsic factors such as body mass (M_b) and ambient temperature (T_a) are well established triggers of torpor. Interestingly, the interplay betweenM_band climate with differentT_aon torpor traits in bats remains unexplored. Using open flow respirometry, we calculatedT_aupon entering torpor (T_at), the reduction in torpid metabolic rate relative to the basal metabolic rate (TMR_red), theT_aat which torpor metabolic rate reached its minimum (T_aadjust), and minimum torpid metabolic rate (TMR_min) in 11 bat species of the family Vespertilionidae that differ inM_bfrom warm and cold climates. We also includedTMR_mindata retrieved through a bibliography review. We tested the effects ofM_band climate on torpor traits using mixed-effect phylogenetic models. All models showed a significant interaction betweenM_band climate. This interaction was inversely related toT_at,TMR_red,T_aadjust, and positively related toTMR_min. These results are likely explained by the differences inM_band the metabolic rate of bats from different climates, which may allow individuals to express torpor in places with differentT_a. Further studies to assess torpor use in bats of different climates are proposed.