Abstract
Bats are among the most successful groups of Australian arid-zone mammals and, therefore, must cope with pronounced seasonal fluctuations in ambient temperature (T a), food availability and unpredictable weather patterns. As knowledge about the energy conserving strategies in desert bats is scant, we used temperature-telemetry to quantify the thermal physiology of tree-roosting inland freetail bats (Mormopterus species 3, 8.5 g, n = 8) at Sturt National Park over two summers (2010–2012), when T a was high and insects were relatively abundant. Torpor use and activity were affected by T a. Bats remained normothermic on the warmest days; they employed one “morning” torpor bout on most days and typically exhibited two torpor bouts on the coolest days. Overall, animals employed torpor on 67.9 % of bat-days and torpor bout duration ranged from 0.5 to 39.3 h. At any given T a, torpor bouts were longer in Mormopterus than in bats from temperate and subtropical habitats. Furthermore, unlike bats from other climatic regions that used only partial passive rewarming, Mormopterus aroused from torpor using either almost entirely passive (68.9 % of all arousals) or active rewarming (31.1 %). We provide the first quantitative data on torpor in a free-ranging arid-zone molossid during summer. They demonstrate that this desert bat uses torpor extensively in summer and often rewarms passively from torpor to maximise energy and water conservation.
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Abbreviations
- T a :
-
Ambient temperature
- T skin :
-
Skin temperature
- T b :
-
Body temperature
- TBD:
-
Torpor bout duration
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Acknowledgments
Special thanks go to Ingrid Witte and the New South Wales National Parks and Wildlife Service for providing accommodation, a quad bike and help with organising the field work. Ulrike Klöcker, Barb Hawerkamp and Dan Hough helped during the field work. We are grateful to Chris Turbill for permission to use his data on Nyctophilus geoffroyi. Stuart Cairns and Thomas Ruf helped and advised with statistical procedures. Daniella Rojas and Shannon Currie helped with different aspects of this project. The research was conducted under permits from the New South Wales National Parks and Wildlife Service and the UNE Animal Ethics Committee. Financial support was received from the University of New England to AB and the Australian Research Council to FG.
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Communicated by I.D. Hume.
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Bondarenco, A., Körtner, G. & Geiser, F. Some like it cold: summer torpor by freetail bats in the Australian arid zone. J Comp Physiol B 183, 1113–1122 (2013). https://doi.org/10.1007/s00360-013-0779-7
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DOI: https://doi.org/10.1007/s00360-013-0779-7