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Dryad

Torpor use in the wild by one of the world's largest bats

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Jun 11, 2024 version files 1.93 MB

Abstract

Torpor is widespread among bats, presumably because most species are small and torpor greatly reduces their high mass-specific resting energy expenditure, especially in the cold. Torpor has not been recorded in any bat species larger than 50 g, yet in theory could be beneficial even in the world's largest bats (flying foxes; Pteropus spp.) that are exposed to adverse environmental conditions associated with energy bottlenecks. We used temperature telemetry to measure body temperature in wild-living adult male grey-headed flying foxes (P. poliocephalus; mean body mass: 799 g) during winter in southern Australia. We found that all individuals used torpor while day-roosting, with body temperatures as low as 27 °C. Torpor was recorded during cold, wet, and windy weather, strongly suggesting it is an adaptation to reduce energy expenditure during periods of increased thermoregulatory costs and depleted body energy stores. Our study has implications for our understanding of the distribution, behavioural ecology, and life history of flying foxes. Furthermore, our discovery increases the body mass of bats known to use torpor by more than tenfold and extends the documented use of this energy-saving strategy under wild conditions to all bat superfamilies, with important implications for the evolutionary maintenance of torpor among bats and other mammals.