title: Cold and alone? Roost choice and season affect torpor patterns in lesser short-tailed bats.
abstract: Seasonal changes in weather and food availability differentially impact energy budgets of small mammals such as bats. While most thermal physiological research has focused on species that experience extreme seasonal temperature variations, knowledge is lacking from less variable temperate to subtropical climates. We quantified ambient temperature (Ta) and skin temperature (Tsk) responses by individuals from a population of New Zealand lesser short-tailed bats (Mystacina tuberculata) during summer and winter using temperature telemetry. During summer, communal roosts were more thermally stable than Ta. During winter, solitary roosts were warmer than Taindicating significant thermal buffering. Communal roost trees were used on 83 % of observation days during summer, and individuals occupying them rarely entered torpor. Solitary roosts were occupied on 93 % of observation days during winter, and 100 % of individuals occupying them used torpor. During summer and winter, bats employed torpor on 11 and 95 % of observation days, respectively. Maximum torpor bout duration was 120.8 h and winter torpor bout duration correlated negatively with mean Ta. Torpor bout duration did not differ between sexes, although female minimum Tskwas significantly lower than males. The summer Heterothermy Index varied, and was also significantly affected by Ta. Mean arousal time was correlated with sunset time and arousals occurred most frequently on significantly warmer evenings, which are likely associated with an increased probability of foraging success. We provide the first evidence that torpor is used flexibly throughout the year by M. tuberculata, demonstrating that roost choice and season impact torpor patterns. Our results add to the growing knowledge that even small changes in seasonal climate can have large effects on the energy balance of small mammals.
authors: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. zcze255@aucklanduni.ac.nz.
authors: Zenon J
authors: ZJ
authors: Czenze
authors: Department of Biology, University of Regina, Regina, SK, Canada.
authors: R Mark
authors: RM
authors: Brigham
authors: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
authors: Anthony J R
authors: AJR
authors: Hickey
authors: School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.|School for Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, QLD, Australia.
authors: Stuart
authors: S
authors: Parsons
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D002685:Chiroptera; D003080:Cold Temperature; D005260:Female; D008297:Male; D012621:Seasons; D012881:Skin Temperature; D064348:Torpor
keywords: Microhabitat; Mystacina tuberculata; Seasonal weather; Thermoregulation; Torpor