When picturing a ground squirrel, it’s common to imagine a creature stuffing its cheeks with nuts or seeds. However, a groundbreaking study has revealed an unexpected facet of California ground squirrels’ behavior: these rodents are active hunters that prey on small mammals like voles. This discovery, led by researchers from the University of Wisconsin-Eau Claire and the University of California, Davis, is the first to document widespread carnivorous tendencies in these squirrels.
Published in the Journal of Ethology, the research challenges the long-held notion that California ground squirrels are strictly granivorous. Instead, it highlights their adaptability as opportunistic omnivores capable of adjusting their diet to exploit available resources.
The observations were conducted in 2024 at Briones Regional Park in Contra Costa County, California. Between June and July, researchers documented 74 interactions between ground squirrels and voles, with 42% involving active hunting. The peak of this carnivorous behavior coincided with a population boom of voles in early July, as reported by citizen scientists on platforms like iNaturalist.

This was shocking said Jennifer E. Smith, the study’s lead author and an associate professor of biology at UW-Eau Claire. Ground squirrels are so familiar to us—they’re in our backyards, at parks—but here’s a behavior that was never observed before, fundamentally altering our understanding of their natural history.
Sonja Wild, a co-lead researcher and postdoctoral scholar at UC Davis, echoed the sentiment. When students first described the behavior, I was skeptical. Then I saw the videos—it was undeniable. Once we started looking for it, we noticed it almost daily.
Through video footage, photographs, and direct field observations, the researchers documented ground squirrels across all ages and sexes actively hunting, consuming, and even competing for vole prey. Interestingly, this behavior appeared limited to voles, with no evidence of predation on other small mammals.
The findings underscore the behavioral flexibility of California ground squirrels, a trait that likely aids their survival in rapidly changing environments. The ability to adjust dietary habits based on resource availability is crucial, explained Wild. In this case, the sudden abundance of voles may have triggered predatory behavior.
Smith added that such adaptability is not unique to ground squirrels. From raccoons and coyotes to humans, behavioral flexibility allows many mammals to thrive in human-altered landscapes.
This discovery also raises new questions. Is this predatory behavior learned or instinctual? Does it impact the squirrels’ reproduction or survival rates? How widespread is this behavior across other populations? These questions remain unanswered but are top priorities for future research.
The study exemplifies the importance of combining traditional fieldwork with modern technology. While digital tools like iNaturalist played a crucial role in spotting trends, the researchers emphasized the irreplaceable value of direct observation. The natural world never fails to surprise us, said Smith.
The team plans to continue their research next summer to assess whether the observed hunting behavior impacts squirrel reproduction or ecological dynamics. For now, this discovery highlights the complexity of species often dismissed as mundane and the importance of studying even the most familiar creatures with fresh eyes.
As Smith aptly put it: The more we explore, the more we realize how much we still have to learn about the world around us.
SOURCES
University of California, Davis
Smith, J.E., Ingbretson, J.E., Miner, M.M. et al. Vole hunting: novel predatory and carnivorous behavior by California ground squirrels. J Ethol (2024). doi.org/10.1007/s10164-024-00832-6
Discover more from LBV Magazine English Edition
Subscribe to get the latest posts sent to your email.