For Belding's ground squirrels, adult females are more likely to survive from year to year if they live near more adult female kin – but neither males nor young females get the same boost from nearby family. Jill Mateo and colleagues at the University of Chicago, USA, report these findings on November 4, 2026, in the open access journal PLOS One.
Belding's ground squirrels are hibernating rodents that live in the mountains of California, Nevada and Oregon. While young males leave home to find new territories, females stay put and live in communal family groups. The female kin alert each other to danger and protect each other's offspring from infanticide.
To identify factors that improve the odds of survival in Belding's ground squirrels, the study's authors analyzed two decades of mark-recapture data, where researchers tagged squirrels and checked the subsequent year to see if they survived. Specifically, they looked at the impact of age, sex, weight, number of offspring, the number of nearby family members and certain hormones. Researchers also took into account annual snowfall.
The analysis showed that, as expected, heavier individuals were more likely to survive hibernation. Females had higher survival rates than males, with juvenile males experiencing the highest mortality. For adult females, the odds of surviving increased with the number of other adult female family members living nearby. This may be because they can share the burden of defending their territory and spend more time foraging. Young females did not experience the same benefits from nearby female relatives, however, likely because they faced stiffer competition for food and burrows. The researchers also showed that a short snowy season allowed the squirrels to emerge earlier from hibernation, which increased the survival of juvenile animals and helped adult females to have more offspring.
Together, these results show that an animal's social structure, physiological state and response to the climate all interact to shape their survival – depending on their sex and life stage. The findings also highlight the importance of having larger kin groups for female Belding's ground squirrels, a unique finding among mammals, where strong social bonds enhance longevity, especially for females. The authors point out that understanding these interactions will be increasingly important in the future, as snowfall declines across much of the Belding's ground squirrels' range due to climate change.
The authors add: "We analyzed which variables predicted year-to-year survival in a group-living species which hibernates most of the year. We found that the number of living female relatives, beyond their mere presence, significantly boosted an adult female's chances of survival, something that has never been shown before. We also expected snow fall to improve survival through insulative properties, but instead lower snow fall was associated with surviving to the following year, likely through phenological effects on summer activity patterns."
"After collecting 25 years of demographic data on Belding's ground squirrels at our eastern Sierra field site, I was eager to discover what influenced survival. Why, for example, our oldest female and male both lived nine years, but most adults live only 2-3 years. Of course, it is a complex interaction of physiological, social and ecological effects, but the previously unknown importance of kin count now begs the question of which mechanisms drive that effect."
In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/47UrxeR
Citation: Mateo JM, Brooks KC, Dosmann A (2026) Kin count: Social, physiological, and environmental correlates of annual survival in Belding's ground squirrels. PLoS One 21(11): e0358786. https://doi.org/10.1371/journal.pone.0358786
Author countries: USA.
Funding: JMM National Science Foundation IOB 05-17137 nsf.gov JMM National Science Foundation IBN 98-08704 nsf.gov JMM National Institutes of Health R01 MH63921-01A1 nih.gov Organizations played no role in the work presented here.
