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Climate impacts on hibernating squirrels

Changing climates are impacting on squirrel populations by prolonging their hibernation, a study suggests.

Research into Columbian ground squirrels, which live in the Rocky Mountains, has revealed that heavy winter snowfalls are delaying the animals’ emergence from their winter burrows.

This could prevent female ground squirrels from gaining enough weight during their short summer to give birth to healthy offspring and to survive the next season’s hibernation.

Severe winters

An international team of scientists led by the Universities of Edinburgh and Alberta studied the creatures in Alberta, Canada.

Columbian ground squirrels typically hibernate for eight or nine months of the year.

They found that the squirrels tended to stay underground for longer during winters with heavy snowfall.

Over the 20-year study, late-season snowfalls increased, which kept the squirrels underground for an extra half-day per year on average.

Population impact

Increased precipitation, in the form of heavy snow, is delaying the timing of a key aspect in the ground squirrels’ year.

Professor Loeske KruukSchool of Biological Sciences

Researchers found that in those years when squirrels emerged late from their burrows, both mothers and pups were less likely to survive.

Overall, population growth has fallen over the two decades of the study.

Scientists say their findings suggest that forecasts of worsening winters, if accurate, could lead to further population decline.

Joint research

The study, published in Nature, was carried out in collaboration with the Centre d’Ecologie Fonctionelle et Evolutive in France and Auburn University in Alabama.

Research was supported by the Royal Society.

Previous studies on the effect of climate change on animals have linked warmer temperatures to earlier timing of key events, such as birds breeding earlier in the year. This study reveals a different aspect of climate change.

Professor Loeske KruukSchool of Biological Sciences