What is winter? Modelling spatial variation in bat host traits and
hibernation and their implications for overwintering energetics
Abstract
White-nose syndrome (WNS) has decimated hibernating bat populations
across eastern and central North America for over a decade. Disease
severity is driven by the interaction between bat characteristics, the
cold-loving fungal agent, and the hibernation environment. While we
further improve hibernation energetics models, we have yet to examine
how spatial heterogeneity in host traits is linked to survival in this
disease system. Here we develop predictive spatial models of body mass
for the little brown myotis (Myotis lucifugus) and reassess previous
definitions of the duration of hibernation of this species. Using data
from published literature, public databases, local experts, and our own
fieldwork, we fit a series of generalized linear models with
hypothesized abiotic drivers to create distribution-wide predictions of
pre-hibernation body fat and hibernation duration. Our results provide
improved estimations of hibernation duration and identify a scaling
relationship between body mass and body fat; this relationship allows
for the first continuous estimates of pre-hibernation body mass and fat
across the species’ distribution. We used these results to inform a
hibernation energetic model to create spatially-varying fat use
estimates for M. lucifugus. These results predict that WNS mortality of
newly and soon-to-be infected M. lucifugus populations in western North
America may be comparable to the substantial die-off observed in eastern
and central populations.