As the Arctic warms, female Arctic ground squirrels end hibernation earlier than males-a discrepancy with major ecological consequences, according to a University of Alaska Fairbanks study published in Science. Winter temperatures play a key role in the populations of many species living at higher latitudes.
However, in the Arctic, where warming occurs more rapidly than in most other places on Earth, winter temperatures are altering the phenology, or timing, of important seasonal behaviors of animals, such as migration or hibernation.
However, despite the rapid rate of climate warming in the Arctic, few long-term studies combine physical records of climate change and physiological responses of Arctic species.
To assess the physiological impact of recent climate change on Arctic squirrels (Urocitellus parryii), Helen Chmura and colleagues combined long-term records of air and soil temperatures at two Arctic sites in Alaska with a 25-year hibernation record for this species.
They found that, in recent decades, winter permafrost freezing has slowed, causing a shift in the timing and duration of body heat generation during squirrel hibernation.
The authors argue that this phenological discrepancy could potentially have a variety of impacts on Arctic ground squirrel population dynamics and the functioning of Arctic food webs. While reduced thermogenesis due to warming temperatures could allow squirrels to conserve energy and thus increase winter survival, a reduced hibernation season could also increase the animals’ exposure to hungry predators, altering mortality rates, particularly for early female squirrels. The phenological discrepancy between the sexes may also disrupt reproductive rates. And on longer time scales, continued warming in the Arctic may lead to changes in seasonal behaviors of male squirrels, the authors say.