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

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.