Abstract
Hibernation provides a means of escaping the metabolic challenges
associated with seasonality, yet the ability of mammals to prolong or
re-enter seasonal dormancy in response to extreme weather events is
unclear. Here, we show that arctic ground squirrels in northern Alaska
exhibited sex-dependent plasticity in the physiology and phenology of
hibernation in response to a series of late spring snowstorms in 2013 that
resulted in the latest snow-melt on record. Females and non-reproductive
males responded to the >1 month delay in snow-melt by extending
heterothermy or re-entering hibernation after several days of euthermy,
leading to a >2-week delay in reproduction compared to surrounding
years. In contrast, reproductive males neither extended nor re-entered
hibernation, likely because seasonal gonadal growth and development and
subsequent testosterone release prevents a return to torpor. Our findings
reveal intriguing differences in responses of males and females to
climatic stressors which can generate a phenological mismatch between the
sexes.