Beat the heat: Movements of a cold-adapted ungulate during a record-breaking heat wave

The frequency and severity of extreme weather events such as heat waves
are increasing globally, revealing ecological responses that provide
valuable insights towards the conservation of species in a changing
climate. In this study, we utilized data from two populations of
GPS-collared female wood bison (Bison bison athabascae) in the boreal
forest of northwestern Canada to investigate their movement behaviours in
response to the 2021 Western North American Heat Wave. Using generalized
additive mixed effect models and a model selection framework, we
identified a behavioural temperature threshold for wood bison at 21°C.
Above this threshold movement rates decreased from ~100 m/hr at 21°C to a
low of ~25 m/hr at 39°C (150% decrease; -9%/°C). Extreme heat also
contributed to changes in diurnal movement patterns, reducing wood bison
movement rates and shifting the timing of peak activity from midday to
early morning. These findings highlight the behavioural adaptations of
female wood bison and underscore the need to understand the behavioural
and physiological responses of cold-adapted mammals to extreme weather
events. Subsequent effects of thermoregulatory behaviour may impact
individual fitness and population viability, particularly at high
latitudes where cold-adapted species are increasingly exposed to severe
weather resulting from anthropogenic climate change.