Hibernation by tree-roosting bats

  • Christopher TurbillEmail author
  • Fritz Geiser
Original Paper


In summer, long-eared bats (Nyctophilus spp.) roost under bark and in tree cavities, where they appear to benefit from diurnal heating of roosts. In contrast, hibernation is thought to require a cool stable temperature, suggesting they should prefer thermally insulated tree cavities during winter. To test this prediction, we quantified the winter thermoregulatory physiology and ecology of hibernating tree-roosting bats, Nyctophilus geoffroyi and N. gouldi in the field. Surprisingly, bats in winter continued to roost under exfoliating bark (65%) on the northern, sunny side of trees and in shallow tree cavities (35%). Despite passive re-warming of torpid bats by 10–20°C per day, torpor bouts lasted up to 15 days, although shorter bouts were also common. Arousals occurred more frequently and subsequent activity lasted longer on warmer nights, suggesting occasional winter foraging. We show that, because periodic arousals coincide with maximum roost temperatures, when costs of rewarming and normothermic thermoregulation are minimal, exposure to a daily temperature cycle could largely reduce energy expenditure during hibernation. Our study provides further evidence that models of torpor patterns and energy expenditure from hibernators in cold temperate climates are not directly applicable in milder climates, where prolonged torpor can be interspersed with more frequent arousals and occasional foraging.


Arousal Bat Hibernation Nyctophilus Torpor 



Metabolic rate


Ambient temperature


Body temperature


Skin temperature



We thank Rebecca Drury for help trapping bats and Stuart Cairns for statistical guidance. This study was conducted under a Scientific Licence from the Department of Environment and Climate Change NSW and with the approval of the University of New England Animal Ethics Committee. The project was supported by a Student Scholarship from Bat Conservation International and an Australian Postgraduate Award to CT and a grant from the Australian Research Council to FG.


  1. Arlettaz R, Ruchet C, Aeschimann J, Brun E, Genoud M, Vogel P (2000) Physiological traits affecting the distribution and wintering strategy of the bat Tadarida teniotis. Ecology 81:1004–1014Google Scholar
  2. Audet D, Thomas DW (1996) Evaluation of the accuracy of body temperature measurement using external radio transmitters. Can J Zool 74:1778–1781CrossRefGoogle Scholar
  3. Avery MI (1985) Winter activity of pipistrelle bats. J Anim Ecol 54:721–738CrossRefGoogle Scholar
  4. Barclay RMR, Kalcounis MC, Crampton LH, Stefan C, Vonhof MJ, Wilkinson L, Brigham RM (1996) Can external radio-transmitters be used to assess body temperature and torpor in bats. J Mammal 77:1102–1106CrossRefGoogle Scholar
  5. Brigham RM, Geiser F (1998) Seasonal activity of two species of Nytophilus bats based on mist-net captures. Aust Mammal 20:349–352Google Scholar
  6. Buck LC, Barnes B (2000) Effects of ambient temperature on metabolic rate, respiratory quotient, and torpor in an artic hibernator. Am J Physiol 279:R255–R262Google Scholar
  7. Dausmann KH, Glos J, Ganzhorn JU, Heldmaier G (2005) Hibernation in the tropics: lessons from a primate. J Comp Physiol B 175:147–155CrossRefPubMedGoogle Scholar
  8. Davis WH, Reite OB (1967) Responses of bats from temperate regions to changes in ambient temperature. Biol Bull 132:320–328CrossRefPubMedGoogle Scholar
  9. French AR (1982) Effects of temperature on the duration of arousal episodes during hibernation. J Appl Physiol 52:216–220PubMedGoogle Scholar
  10. French AR (1985) Allometries of the durations of torpid and normothermic intervals during mammalian hibernation: a test of the theory of metabolic control of the timing of changes in body temperature. J Comp Physiol B 156:13–19CrossRefPubMedGoogle Scholar
  11. Geiser F (2004) Metabolic rate and body temperature reduction during hibernation and daily torpor. Annu Rev Physiol 66:239–274CrossRefPubMedGoogle Scholar
  12. Geiser F (2007) Yearlong hibernation in a marsupial mammal. Naturwissenschaften 94:941–944CrossRefPubMedGoogle Scholar
  13. Geiser F, Kenagy GJ (1988) Torpor duration in relation to temperature and metabolism in hibernating ground squirrels. Physiol Zool 61:442–229Google Scholar
  14. Geiser F, Ruf T (1995) Hibernation versus daily torpor in mammals and birds: physiological variables and classification of torpor patterns. Physiol Zool 68:935–966Google Scholar
  15. Geiser F, Brigham RM (2000) Torpor, thermal biology, and energetics in Australian long-eared bats (Nyctophilus). J Comp Physiol B 170:153–162CrossRefPubMedGoogle Scholar
  16. Geiser F, Drury R, Körtner G, Turbill C, Pavey CR and Brigham RM (2004) Passive re-warming in mammals and birds: energetic, ecological and evolutionary implications. In: Barnes BM and Carey HC (eds) Life in the cold. Evolution, adaptation and application. University of Alaska, Fairbanks, Alaska USA, pp 51–62Google Scholar
  17. Hall M (1832) On hybernation. Phil Trans R Soc 122:335–360CrossRefGoogle Scholar
  18. Hays GC, Speakman JR, Webb PI (1992) Why do long-eared bats (Plecotus auritus) fly in winter? Physiol Zool 65:554–567Google Scholar
  19. Heller HC, Hammel HT (1972) CNS control of body temperature during hibernation. Comp Biochem Physiol 41A:349–359CrossRefGoogle Scholar
  20. Hock RJ (1951) The metabolic rates and body temperatures of bats. Biol Bull 101:289–299CrossRefGoogle Scholar
  21. Hosken DJ (1997) Reproduction and the female reproductive cycle of Nyctophilus geoffroyi and N. major (Chiroptera: Vespertilionidae) from south-western Australia. Aust J Zool 45:489–504CrossRefGoogle Scholar
  22. Hosken DJ, Blackberry TB, Stucki AF (1998) The male reproductive cycle of three species of Australian vespertilionid bat. J Zool (Lond) 245:261–270CrossRefGoogle Scholar
  23. Humphries MM, Thomas DW, Speakman JR (2002) Climate-mediated energetic constraints on the distribution of hibernating mammals. Nature 418:313–316CrossRefPubMedGoogle Scholar
  24. Körtner G, Geiser F (1998) Ecology of natural hibernation in the marsupial mountain pygmy possum (Burramys parvus). Oecologia 113:170–178CrossRefGoogle Scholar
  25. Körtner G, Geiser F (2000) The temporal organization of daily torpor and hibernation: circadian and circannual rhythms. Chronobiol Int 17:103–128CrossRefPubMedGoogle Scholar
  26. Kunz TH (1974) Feeding ecology of a temperate insectivorous bat (Myotis velifer). Ecology 55:693–711CrossRefGoogle Scholar
  27. Kunz TH, Lumsden LF (2003) Ecology of cavity and foliage roosting bats. In: Kunz TH, Fenton MB (eds) Bat ecology. University of Chicago Press, Chicago, pp 3–89Google Scholar
  28. Kunz TH, Wrazen JA, Burnett CD (1998) Changes in body mass and fat reserves in pre-hibernating little brown bats (Myotis lucifugus) Ecoscience 5:8–17Google Scholar
  29. Lyman CP (1970) Thermoregulation and metabolism in bats. In: Wimsatt WA (ed) Biology of bats. Academic Press, New York, pp 301–330Google Scholar
  30. McNab BK (1982) Evolutionary alternatives in the physiological ecology of bats. In: Kunz TH (ed) Ecology of bats. Plenum Press, New York, pp 151–196Google Scholar
  31. Nagel A, Nagel R (1991) How do bats choose optimal temperatures for hibernation? Comp Biochem Physiol 99A:323–326CrossRefGoogle Scholar
  32. O’Donnell CFJ, Sedgeley JA (2006) Causes and consequences of tree-cavity roosting in a temperate bat, Chalinolobus tuberculatus, from New Zealand. In: Zubaid A, McCracken GF, Kunz TH (eds) Functional and evolutionary ecology of bats. Oxford University Press, New York, pp 308–328Google Scholar
  33. Park KJ, Jones G, Ransome RD (2000) Torpor, arousal and activity of hibernating greater horseshoe bats (Rhinolophus ferrumequinum). Funct Ecol 14:580–588CrossRefGoogle Scholar
  34. Phillips WR, Inwards SJ (1985) The annual activity and breeding cycles of Gould’s long-eared bat, Nyctophilus gouldi (Microchiroptera: Vespertilionidae). Aust J Zool 33:111–126CrossRefGoogle Scholar
  35. Racey PA (1982) Ecology of bat reproduction. In: Kunz TH (ed) Ecology of bats. Plenum Press, New York, pp 57–104Google Scholar
  36. Ransome RD (1971) The effect of ambient temperature on the arousal frequency of the hibernating greater horseshoe bats, Rhinolophus ferrumequinum, in relation to site selection and the hibernation state. J Zool (Lond) 164:353–371CrossRefGoogle Scholar
  37. Sluiter JW, Voute AM, van Heerdt PF (1973) Hibernation of Nyctalus noctula. Period Biol 75:181–188Google Scholar
  38. Speakman JR, Racey PA (1989) Hibernal ecology of the pipistrelle bat: energy expenditure, water requirements and mass loss, implications for survival and the function of winter emergence flights. J Anim Ecol 58:797–813CrossRefGoogle Scholar
  39. Speakman JR, Thomas DW (2003) Physiological ecology and energetics of bats. In: Kunz TH, Fenton MB (eds) Bat ecology. University of Chicago Press, Chicago, pp 430–492Google Scholar
  40. Speakman JR, Webb PI, Racey PA (1991) Effects of disturbance on the energy expenditure of hibernating bats. J Appl Ecol 28:1087–1104CrossRefGoogle Scholar
  41. Taylor LR (1963) Analysis of the effect of temperature on insects in flight. J Anim Ecol 32:99–117CrossRefGoogle Scholar
  42. Thomas DW (1995) The physiological ecology of hibernation in vespertilionid bats. In: Racey PA, Swift SM (eds) Ecology, evolution and behaviour of bats. Clarendon Press, Oxford, pp 233–244Google Scholar
  43. Thomas DW, Cloutier D (1992) Evaporative water loss by hibernating little brown bats, Myotis lucifugus. Physiol Zool 65:443–456Google Scholar
  44. Thomas DW, Geiser F (1997) Periodic arousals in hibernating mammals: is evaporative water loss involved? Funct Ecol 11:585–591CrossRefGoogle Scholar
  45. Thomas DW, Dorais J, Bergeron JM (1990) Winter energy budgets and costs of arousal for hibernating little brown bats, Myotis lucifugus. J Mammal 71:475–479CrossRefGoogle Scholar
  46. Tidemann CR (1982) Sex differences in seasonal changes of brown adipose tissue and activity of the Australian vespertilionid bat Eptesicus vulturnus. Aust J Zool 30:15–22CrossRefGoogle Scholar
  47. Turbill C (2006a) Thermoregulatory behaviour of tree-roosting chocolate wattled bats (Chalinolobus morio) during summer and winter. J Mammal 87:318–323CrossRefGoogle Scholar
  48. Turbill C (2006b) Roosting and thermoregulatory behaviour of male Gould’s long-eared bats, Nyctophilus gouldi: energetic benefits of thermally unstable tree roosts. Aust J Zool 54:57–60CrossRefGoogle Scholar
  49. Turbill C (2006c) Thermoregulatory physiology and ecology of tree-roosting bats. PhD Thesis, University of New England, Armidale, AustraliaGoogle Scholar
  50. Turbill C, Körtner G, Geiser F (2003) Natural use of heterothermy by a small, tree-roosting bat during summer. Physiol Biochem Zool 76:868–876CrossRefPubMedGoogle Scholar
  51. Twente JW, Twente JA (1965) Effects of core temperature upon duration of hibernation of Citellus lateralis. J Appl Physiol 20:411–416PubMedGoogle Scholar
  52. Twente JW, Twente J, Brack V Jr (1985) The duration of the period of hibernation of three species of vespertilionid bats. II. Laboratory studies. Can J Zool 63:2955–2961Google Scholar
  53. Van Breukelen F, Martin SL (2002) Molecular adaptations in mammalian hibernators: unique adaptations or generalized responses? J Appl Physiol 92:2640–2647PubMedGoogle Scholar
  54. Wang LCH (1978) Energetic and field aspects of mammalian torpor: the Richardson’s ground squirrel. In: Wang LCH, Hudson JW (eds) Strategies in cold: natural torpidity and thermogenesis. Academic Press, New York, pp 109–146Google Scholar
  55. Webb PI, Speakman JR, Racey PA (1995) How hot is a hibernaculum? A review of the temperatures at which bats hibernate. Can J Zool 74:761–765CrossRefGoogle Scholar
  56. Williams CB (1961) Studies of the effect of weather conditions on the activity and abundance of insect populations. Phil Trans R Soc B 244:42–369CrossRefGoogle Scholar
  57. Willis JS (1982) The mystery of the periodic arousal. In: Lyman CP, Willis JS, Malan A, Wang LCH (eds) Hibernation and torpor in mammals and birds. Academic Press, New York, pp 92–103Google Scholar
  58. Willis CKR, Brigham RM (2003) Defining torpor in free-ranging bats: experimental evaluation of external temperature-sensitive radiotransmitters and the concept of active temperature. J Comp Physiol B 173:173–389CrossRefGoogle Scholar
  59. Willis CKR, Brigham RM, Geiser F (2006) Deep, prolonged torpor by pregnant free-ranging bats. Naturwissenschaften 93:80–83CrossRefPubMedGoogle Scholar
  60. Zar JH (1999) Biostatistical analysis, 4th ed. Prentice Hall International, New JerseyGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Department of ZoologyUniversity of New EnglandArmidaleAustralia

Personalised recommendations