Interspecific variation in evaporative water loss and temperature response, but not metabolic rate, among hibernating bats

Hibernation is widespread among mammals in a variety of environmental
contexts. However, few experimental studies consider interspecific
comparisons, and for many unstudied (or understudied) species we must
assume the underlying physiology of hibernation is comparable to the
relatively few species that have been studied in detail. Studies of
interspecific variation provide insight into general patterns of
hibernation strategies. We studied 13 species of free-living bats,
including populations spread over thousands of kilometers and diverse
habitats. We measured torpid metabolic rate and evaporative water loss
(two key parameters for understanding hibernation energetics) across a
range of temperatures. Response to ambient temperature varied among
species, but all species achieved similar minimum torpid metabolic rate.
Conversely,  evaporative water loss varied among species and our
results suggest two general hibernation strategies in North American bats,
representing high and low evaporative water loss groups. Notably, species
that have suffered population declines due to white-nose syndrome fall in
the high evaporative water loss group and less affected species in the low
evaporative water loss group. Documenting general patterns of
physiological diversity, and associated ecological implications,
contributes to broader understanding of biodiversity, and may help predict
which species are at greater risk of environmental and anthropogenic
stressors.