Adult female Belding's ground squirrels survive hibernation at higher rates when they live near more adult female relatives, according to research led by Jill Mateo at the University of Chicago. The team published their findings on November 4, 2026, in PLOS One.
Researchers analyzed two decades of mark-recapture data from Belding's ground squirrels, which live in the mountains of California, Nevada and Oregon. They tracked whether tagged squirrels survived from one year to the next, examining factors including age, sex, weight, number of offspring, nearby family members, certain hormones, and annual snowfall.
The analysis revealed that heavier individuals survived hibernation more often. Females survived at higher rates than males, with juvenile males experiencing the highest mortality. For adult females, survival odds increased with the number of other adult female relatives nearby. The researchers suggest this may occur because these females can share territory defense duties and spend more time foraging.
Young females did not show the same survival benefit from nearby female relatives, likely because they faced stiffer competition for food and burrows. Shorter snowy seasons allowed squirrels to emerge earlier from hibernation, which increased juvenile survival and helped adult females produce more offspring.
The authors note that a female Belding's ground squirrel's survival depends on interactions between social structure, physiological state, and climate response, varying by sex and life stage. They emphasize that the importance of larger kin groups for female survival has never been documented before in mammals. The team adds that understanding these interactions will become increasingly important as snowfall declines across the species' range due to climate change.