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Torpor and thermal energetics in a tiny Australian vespertilionid, the little forest bat (Vespadelus vulturnus)

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Data on thermal energetics for vespertilionid bats are under-represented in the literature relative to their abundance, as are data for bats of very small body mass. Therefore, we studied torpor use and thermal energetics in one of the smallest (4 g) Australian vespertilionids, Vespadelus vulturnus. We used open-flow respirometry to quantify temporal patterns of torpor use, upper and lower critical temperatures (T uc and T lc) of the thermoneutral zone (TNZ), basal metabolic rate (BMR), resting metabolic rate (RMR), torpid metabolic rate (TMR), and wet thermal conductance (C wet) over a range of ambient temperatures (T a). We also measured body temperature (T b) during torpor and normothermia. Bats showed a high proclivity for torpor and typically aroused only for brief periods. The TNZ ranged from 27.6°C to 33.3°C. Within the TNZ T b was 33.3±0.4°C and BMR was 1.02±0.29 mlO2 g−1 h−1 (5.60±1.65 mW g−1) at a mean body mass of 4.0±0.69 g, which is 55 % of that predicted for a 4 g bat. Minimum TMR of torpid bats was 0.014±0.006 mlO2 g−1 h−1 (0.079±0.032 mW g−1) at T a=4.6±0.4°C and T b=7.5±1.9. T lc and C wet of normothermic bats were both lower than that predicted for a 4 g bat, which indicates that V. vulturnus is adapted to minimising heat loss at low T a. Our findings support the hypothesis that vespertilionid bats have evolved energy-conserving physiological traits, such as low BMR and proclivity for torpor.

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Basal metabolic rate

C wet :

Wet thermal conductance


Metabolic rate


Resting metabolic rate

T a :

Ambient temperature

T b :

Body temperature

T lc :

Lower critical temperature


Torpid metabolic rate


Thermoneutral zone

T uc :

Upper critical temperature

\(\ifmmode\expandafter\dot\else\expandafter\.\fi{V}O_{2} \) :

Rate of oxygen consumption


  • Anthony EL (1988) Age determination in bats. In: Kunz TH (ed) Ecological and behavioral methods for the Study of Bats. Smithsonian Institution, Washington DC, pp 47–58

    Google Scholar 

  • Bradley SR, Deavers DR (1980) A re-examination of the relationship between thermal conductance and body weight in mammals. Comp Biochem Physiol A 65:465–476

    Article  Google Scholar 

  • Churchill S (1998) Australian bats. Reed New Holland, Sydney Australia

    Google Scholar 

  • Cryan PM, Wolf BO (2003) Sex differences in the thermoregulation and evaporative water loss of a heterothermic bat, Lasiurus cinereus, during its spring migration. J Exp Biol 206:3381–3390

    Article  PubMed  Google Scholar 

  • Geiser F (1988) Reduction of metabolism during hibernation and daily torpor in mammals and birds: temperature effect or physiological inhibition? J Comp Physiol B 158:25–37

    Article  PubMed  CAS  Google Scholar 

  • Geiser F (1998) Evolution of daily torpor and hibernation in birds and mammals: importance of body size. Clin Exp Pharmacol Physiol 25:736–740

    Article  PubMed  CAS  Google Scholar 

  • Geiser F (2004) Metabolic rate and body temperature reduction during hibernation and daily torpor. Annu Rev Physiol 66:239–274

    Article  PubMed  CAS  Google Scholar 

  • Geiser F (2005) Energetics, thermal biology, and torpor in Australian bats. In: Akbar Z, McCracken GF, Kunz TH (eds) Functional and evolutionary ecology of bats: Proceedings of the 12th international bat research conference. Oxford University Press, New York (in press)

  • Geiser F, Brigham RM (2000) Torpor, thermal biology and energetics in Australian long-eared bats (Nyctophilus). J Comp Physiol B 170:153–162

    Article  PubMed  CAS  Google Scholar 

  • Geiser F, Drury RL (2003) Radiant heat affects thermoregulation and energy expenditure during rewarming from torpor. J Comp Physiol B 173:55–60

    Article  PubMed  CAS  Google Scholar 

  • Geiser F, Holloway JC, Körtner G, Maddocks TA, Turbill C, Brigham RM (2000) Do patterns of torpor differ between captive and free-ranging mammals and birds? In: Heldmaier G, Klingenspor M (eds) Life in the cold: Proceedings of the 11th international hibernation symposium. Springer, Berlin Heidelberg, New york, pp 95–102

  • Geiser F, Körtner G, Schmidt I (1998) Leptin increases energy expenditure of a marsupial by inhibition of daily torpor. Am J Physiol 275:R1627–R1632

    PubMed  CAS  Google Scholar 

  • Geiser F, Ruf T (1995) Hibernation versus daily torpor in mammals and birds: physiological variables and classification of torpor patterns. Physiol Zool 68:935–966

    Google Scholar 

  • Henshaw RE (1968) Thermoregulation during hibernation: application of Newton’s law of cooling. J Theor Biol 20:79–90

    Article  PubMed  CAS  Google Scholar 

  • Henshaw RE (1970) Thermoregulation in bats. In: Slaughter BH, Walton DW (eds) About bats. Southern Methodist University Press, Dallas, pp 188–232

    Google Scholar 

  • Hosken DJ (1997) Thermal biology and metabolism of the greater long-eared bat, Nyctophilus major (Chiroptera: Vespertilionidae). Aust J Zool 45:145–156

    Article  Google Scholar 

  • Hosken DJ, Withers PC (1999) Metabolic physiology of euthermic and torpid lesser long-eared bats, Nyctophilus geoffroyi (Chiroptera: Vespertilionidae). J Mammal 80:42–52

    Article  Google Scholar 

  • Lausen CL, Barclay RMR (2003) Thermoregulation and roost selection by reproductive female big brown bats (Eptesicus fuscus) roosting in rock crevices. J Zool (Lond) 260:235–244

    Article  Google Scholar 

  • Levy A (1964) The accuracy of the bubble meter method for gas flow measurements. J Sci Instrum 41:449–453

    Article  Google Scholar 

  • Maloney SK, Bronner GN, Buffenstein R (1999) Thermoregulation in the Angolan free-tailed bat, Mops condylurus: a small mammal that uses hot roosts. Physiol Biochem Zool 72:385–396

    Article  PubMed  CAS  Google Scholar 

  • McNab BK (1989) Temperature regulation and rate of metabolism in three Bornean bats. J Mammal 70:153–161

    Article  Google Scholar 

  • McNab BK (1992) A statistical analysis of mammalian rates of metabolism. Funct Ecol 6:672–679

    Article  Google Scholar 

  • McNab BK (2003) Sample size and the estimation of physiological parameters in the field. Funct Ecol 17:82–86

    Article  Google Scholar 

  • Menkhorst P, Knight F (2001) A field guide to the mammals of Australia. Oxford University Press, Melbourne, Australia

    Google Scholar 

  • Nickerson DM, Facey DE, Grossman GD (1989) Estimating physiological thresholds with continuous two-phase regression. Physiol Zool 62:866–887

    Google Scholar 

  • Nowak RM (1991) Walker’s bats of the world. John Hopkins University Press, Baltimore

    Google Scholar 

  • Schmidt-Nielsen K (1984) Scaling: why is animal size so important. Cambridge University Press, New York

    Google Scholar 

  • Smith FA, Lyons SK, Morgan Ernest SK, Jones KE, Kauffman DM, Dayan T, Marquet PA, Brown JH, Haskell JP (2003) Body mass of late quaternary mammals. Ecol 84:3403

    Article  Google Scholar 

  • 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 430–490

    Google Scholar 

  • Turbill C, Körtner G, Geiser F (2003a) Natural use of heterothermy by a small, tree-roosting bat during summer. Physiol Biochem Zool 76:868–876

    Article  PubMed  Google Scholar 

  • Turbill C, Law BS, Geiser F (2003b) Summer torpor in a free-ranging bat from subtropical Australia. J Therm Biol 28:223–226

    Article  Google Scholar 

  • Turbill C, Körtner G, Geiser F (2004) Daily temperature cycles affect energy expenditure and arousal from torpor in a small tree-roosting bat (Nyctophilus geoffroyi). In: Proceedings of the 21st Annual Meeting of the Australian and New Zealand Society for Comparative Physiology and Biochemistry, Dec 9–12, Wollongong, Australia, p 24

  • Willis CKR (2005) Daily heterothermy in temperate bats using natural roosts. In: Akbar Z, McCracken GF, Kunz TH (eds) Functional and evolutionary ecology of bats: In: Proceedings of the 12th International Bat Research Conference. Oxford University Press, New York (in press)

  • 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 173:379–389

    Article  PubMed  CAS  Google Scholar 

  • Willis CKR, Lane JE, Liknes ET, Swanson DL, Brigham RM (2005) Thermal energetics of female big brown bats (Eptesicus fuscus). Can J Zool (in press)

  • Withers PC (1977) Measurement of VO2, VCO2, and evaporative water loss with a flow-through mask. J Appl Physiol 42:120–123

    PubMed  CAS  Google Scholar 

  • Withers PC (2001) Design, calibration and calculation for flow-through respirometry systems. Aust J Zool 49:445–461

    Article  Google Scholar 

  • Zar JH (1999) Biostatistical Analysis. Prentice Hall, Englewood Cliffs

    Google Scholar 

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Our research is funded by a Natural Sciences and Engineering Research Council (Canada) Post-Doctoral Fellowship to CKRW, an Australian Research Council Postgraduate Award to CT, an Australian Research Council (ARC) grant to FG, and the University of New England. All experiments comply with current laws of Australia and were approved by the University of New England Animal Ethics Committee.

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Correspondence to Craig K. R. Willis.

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Communicated by I. D. Hume

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Willis, C.K.R., Turbill, C. & Geiser, F. Torpor and thermal energetics in a tiny Australian vespertilionid, the little forest bat (Vespadelus vulturnus). J Comp Physiol B 175, 479–486 (2005).

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