American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“Sex-dependent phenological plasticity in an arctic hibernator”

Posted on

Cory T. Williams, C. Loren Buck, Michael J. Sheriff, Melanie M. Richter, Jesse S. Krause, and Brian M. Barnes

Hibernation plasticity in response to extreme weather events differs between the sexes in arctic ground squirrels

A female arctic ground squirrel (<i>Urocitellus parryii</i>) wearing a collar.<br />(Credit: Alicia Gillean)
A female arctic ground squirrel (Urocitellus parryii) wearing a collar.
(Credit: Alicia Gillean)

Climate change can increase the frequency, duration, and intensity of extreme weather, but the degree to which hibernating mammals can buffer themselves from these events by prolonging or re-entering seasonal dormancy is unclear. Using a combination of high-resolution body temperature loggers and snow cover observations, the authors show that female arctic ground squirrels will delay their exit from hibernation, and even re-enter hibernation, in response to unseasonable snow storms in late spring. Extended hibernation by females resulted in a two-week delay in the timing of births. However, what is perhaps most interesting about the findings was the sex-specific response: mature males show no flexibility in timing while immature non-reproductive males respond similarly to females. Sex-dependent plasticity results in a mismatch in timing between the sexes, with males ready to mate weeks before receptive females are available on the surface.

A juvenile arctic ground squirrel eating a berry.<br />(Credit: Cory T. Williams)
A juvenile arctic ground squirrel eating a berry.
(Credit: Cory T. Williams)

These types of sex-specific responses to extreme climate events are likely to have significant consequences for population dynamics, though more work is needed to understand whether late spring snowstorms affect the survival of adult males in the spring or the survival of juveniles during their first winter hibernation. Measuring how seasonal timing is affected by climate change is becoming more common, but this study suggests that measuring timing in both sexes may be needed to fully appreciate how climate change can disrupt biological interactions. Read the Article