Evaporative Water Loss by Hibernating Little Brown Bats, Myotis lucifugus

Thomas, Donald W.; Cloutier, Danielle

doi:10.1086/physzool.65.2.30158262

Cited by 121 publications

(129 citation statements)

References 23 publications

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“…Given the small size of Dale's cave this was probably not possible so they re-entered torpor and exhibited long torpor bouts at this same T a . This pattern could also be due to increased evaporative water loss (EWL) in colder, drier air, which may increase the pressure for bats to move to a more humid roost or cluster with other individuals to reduce EWL (Thomas and Cloutier, 1992).…”

Section: Torpor and Arousal Patterns Of Free-ranging Batsmentioning

confidence: 99%

Hibernation energetics of free-ranging little brown bats

Jonasson

Willis

2012

Journal of Experimental Biology

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SUMMARYHibernation physiology and energy expenditure have been relatively well studied in large captive hibernators, especially rodents, but data from smaller, free-ranging hibernators are sparse. We examined variation in the hibernation patterns of free-ranging little brown bats (Myotis lucifugus) using temperature-sensitive radio-transmitters. First, we aimed to test the hypothesis that age, sex and body condition affect expression of torpor and energy expenditure during hibernation. Second, we examined skin temperature to assess whether qualitative differences in the thermal properties of the hibernacula of bats, compared with the burrows of hibernating rodents, might lead to different patterns of torpor and arousal for bats. We also evaluated the impact of carrying transmitters on body condition to help determine the potential impact of telemetry studies. We observed large variation in the duration of torpor bouts within and between individuals but detected no effect of age, sex or body condition on torpor expression or estimates of energy expenditure. We observed the use of shallow torpor in the midst of periodic arousals, which may represent a unique adaptation of bats for conservation of energy during the most costly phase of hibernation. There was no difference in the body condition of hibernating bats outfitted with transmitters compared with that of control bats captured from the same hibernaculum at the same time. This study provides new information on the energetics of hibernation in an underrepresented taxon and baseline data important for understanding how white-nose syndrome, a new disease devastating populations of hibernating bats in North America, may alter the expression of hibernation in affected bats. Supplementary material available online at

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Section: Torpor and Arousal Patterns Of Free-ranging Batsmentioning

confidence: 99%

Hibernation energetics of free-ranging little brown bats

Jonasson

Willis

2012

Journal of Experimental Biology

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“…Benefits of hibernation are obvious (Geiser 2004;Geiser and Brigham 2012) but there are associated costs, such as suppressed molecular synthesis (Lillegraven et al 1987), ceased or delayed reproduction (Racey 1969; Barnes et al 1986), and immunosuppression (Bouma et al 2010). For these reasons and likely others, nearly all hibernating mammals arouse periodically (Willis 1982; French 1985), ostensibly to excrete metabolic wastes (Baumber et al 1971), mount immune responses (Burton and Reichman 1999), mate (Thomas et al 1979), eat (Humphries et al 2001), and possibly drink (Thomas and Cloutier 1992;Thomas and Geiser 1997; Ben-Hamo et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

et al. 2016

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Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset.We recorded echolocation calls to determine correlates of hourly bat-activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as -10.4°C.We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis (Kaup 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and Myotis lucifugus using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity-thermoregulatory heat substitution. IntroductionDuring hibernation, metabolic rate (MR) and body temperature (T b ), are decreased for days to weeks (Ruf and Geiser 2015). Hibernating animals save considerable energy and can survive on limited resources (i.e., body fat or cached food) for extended periods, up to months at a time (Humphries et al. 2003). Benefits of hibernation are obvious (Geiser 2004;Geiser and Brigham 2012) but there are associated costs, such as suppressed molecular synthesis (Lillegraven et al. 1987), ceased or delayed reproduction (Racey 1969; Barnes et al. 1986), and immunosuppression (Bouma et al. 2010). For these reasons and likely others, nearly all hibernating mammals arouse periodically (Willis 1982; French 1985), ostensibly to excrete metabolic wastes (Baumber et al. 1971), mount immune responses (Burton and Reichman 1999), mate (Thomas et al. 1979), eat (Humphries et al. 2001), and possibly drink (Thomas and Cloutier 1992;Thomas and Geiser 1997; Ben-Hamo et al. 2013).Much of what we know about arousals and winter activity of temperate-zone bats comes from research on caverniculous species. In eastern North America, bats often roost in large groups in sizeable, humid, thermally-stable hibernacula (Webb et al. 1996;Perry 2012). Most activities typical of arousals occur within the hibernacula; caves and mines allow flight within hibernacula and may contain open water sources and hibernating insects that can be consumed (Swanson and Evans 1936;Rysgaard 1942). Opportunistic mating is also possible with mixedsex groups typically found in cave hibernacula (Thomas et al. 1979).Bats are also active outside of hibernacula for reasons poorly understood. Early ...

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“…Many different hypotheses attempting to explain periodic arousals have been proposed (Strumwasser, 1959;Galster and Morrison, 1970;Baumber et al, 1971;Daan et al, 1991;Thomas and Cloutier, 1992;Németh et al, 2010), as reviewed by Thomas and Geiser (Thomas and Geiser, 1997). One hypothesis proposes that during hibernation there is an accumulation of metabolic wastes, such as ketone bodies, and a need to replenish energy-rich substrates (Galster and Morrison, 1970;Baumber et al, 1971).…”

Section: Introductionmentioning

confidence: 99%

“…One hypothesis proposes that during hibernation there is an accumulation of metabolic wastes, such as ketone bodies, and a need to replenish energy-rich substrates (Galster and Morrison, 1970;Baumber et al, 1971). Another suggests that bats arouse to restore body water and electrolyte balance (Thomas and Cloutier, 1992;Thomas and Geiser, 1997;Németh et al, 2010). All these hypotheses relate arousals to processes -such as metabolism and water loss -that vary in the same direction with T b and T a .…”

Section: Introductionmentioning

confidence: 99%

Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats

Ben-Hamo

Muñoz‐Garcia

Williams

et al. 2013

Journal of Experimental Biology

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SUMMARYBats hibernate to cope with low ambient temperatures (T a ) and low food availability during winter. However, hibernation is frequently interrupted by arousals, when bats increase body temperature (T b ) and metabolic rate (MR) to normothermic levels. Arousals account for more than 85% of a batʼs winter energy expenditure. This has been associated with variation in T b , T a or both, leading to a single testable prediction, i.e. that torpor bout length (TBL) is negatively correlated with T a and T b . T a and T b were both found to be correlated with TBL, but correlations alone cannot establish a causal link between arousal and T b or T a . Because hydration state has also been implicated in arousals from hibernation, we hypothesized that water loss during hibernation creates the need in bats to arouse to drink. We measured TBL of bats (Pipistrellus kuhlii) at the same T a but under different conditions of humidity, and found an inverse relationship between TBL and total evaporative water loss, independent of metabolic rate, which directly supports the hypothesis that hydration state is a cue to arousal in bats.

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Evaporative Water Loss by Hibernating Little Brown Bats, Myotis lucifugus

Cited by 121 publications

References 23 publications

Hibernation energetics of free-ranging little brown bats

Hibernation energetics of free-ranging little brown bats

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats

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