Roosting and thermoregulatory behaviour of male Gould’s long-eared bats, Nyctophilus gouldi: energetic benefits of thermally unstable tree roosts
Christopher TurbillCentre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia. Email: cturbill@une.edu.au
Australian Journal of Zoology 54(1) 57-60 https://doi.org/10.1071/ZO05068
Submitted: 6 November 2005 Accepted: 5 January 2006 Published: 23 March 2006
Abstract
Information about the thermal biology of bats in relation to their roosting behaviour is scant. I used temperature telemetry to locate roosts and record the thermoregulatory behaviour of male long-eared bats, Nyctophilus gouldi (9 g), during late spring in the Northern Tablelands of New South Wales. Bats roosted under bark and in tree cavities, where they typically experienced wide daily fluctuations in ambient temperature (Ta). On 13 out of 16 days, bats employed two torpor bouts per day, during the early morning and late afternoon, coinciding with times of low Ta. Heating of roosts during the day resulted in up to 20°C of passive re-warming before active arousal and provided high Ta around midday when bats were normothermic. By switching between torpor and normothermic thermoregulation according to the daily Ta cycle, male N. gouldi appear to gain an energetic advantage from choosing poorly insulated and often sun-exposed roosts.
Acknowledgments
I thank Fritz Geiser for project support and critical comments on the manuscript. This study followed procedures approved by the Animal Ethics Committee of the University of New England and was supported by the Australian Research Council and an Australian Postgraduate Award.
Audet, D. , and Thomas, D. W. (1996). Evaluation of the accuracy of body temperature measurement using external radio transmitters. Canadian Journal of Zoology 74, 1778–1781.
Geiser, F. , and Brigham, R. M. (2000). Torpor, thermal biology, and energetics in Australian long-eared bats (Nyctophilus). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 170, 153–162.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Hock, R. J. (1951). The metabolic rates and body temperatures of bats. Biological Bulletin 101, 289–299.
Lausen, C. L. , and Barclay, R. M. R. (2003). Thermoregulation and roost selection by reproductive female big brown bats (Eptesicus fuscus) roosting in rock crevices. Journal of Zoology 260, 235–244.
| Crossref | GoogleScholarGoogle Scholar |
Racey, P. A. (1973). Environmental factors affecting the length of gestation in heterothermic bats. Journal of Reproduction and Fertility. Supplement 19, 175–189.
| PubMed |
Studier, E. H. (1981). Energetic advantages to slight drops in body temperature in little brown bats, Myotis lucifugus. Comparative Biochemistry and Physiology 70A, 537–540.
Thomas, D. W. , Dorais, J. , and Bergeron, J. M. (1990). Winter energy budgets and costs of arousal for hibernating little brown bats, Myotis lucifugus. Journal of Mammalogy 71, 475–479.
Turbill, C. , Körtner, G. , and Geiser, F. (2003a). Natural use of heterothermy by a small, tree-roosting bat during summer. Physiological and Biochemical Zoology 76, 868–876.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Turbill, C. , Law, B. S. , and Geiser, F. (2003b). Summer torpor in a free-ranging bat from sub-tropical Australia. Journal of Thermal Biology 28, 223–226.
| Crossref | GoogleScholarGoogle Scholar |
Willis, C. K. R. , and Brigham, R. M. (2003). Defining torpor in free-ranging bats: experimental evaluation of external temperature-sensitive radiotransmitters and the concept of active temperature. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 173, 379–389.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
