SUDDENLY, THOSE ADORABLE furry squirrels in peoples’ yards may not seem so cute.
A new study from University of California, Davis and University of Wisconsin-Eau Claire chronicle widespread carnivorous behavior among squirrels.
In other words, squirrels are killers.
Voles seem to be the targets of their newfound bloodlust. According to a story posted Wednesday on the UC Davis website, researchers working in Briones Regional Park in Contra Costa County witnessed 74 interactions between squirrels and voles between June and July of this year.
Nearly half — 42% — involved the ground squirrels actively hunting the voles.
“This was shocking,” said lead author Jennifer E. Smith, an associate professor of biology at UW-Eau Claire who leads the long-term ground squirrels project with Sonja Wild of UC Davis. “We had never seen this behavior before. Squirrels are one of the most familiar animals to people. We see them right outside our windows; we interact with them regularly.
“Yet here’s this never-before-encountered-in-science behavior that sheds light on the fact that there’s so much more to learn about the natural history of the world around us,” Smith said.
Researchers said the finding fundamentally changes our understanding of ground squirrels. Published in the Journal of Ethology, the researchers said the study suggests what was considered a granivorous species actually is an opportunistic omnivore and more flexible in its diet than previously assumed.
In other words, squirrels are killers.
The observations occurred in the 12th year of the Long-term Behavioral Ecology of California Ground Squirrels Project conducted at Briones.
Wild said in a statement she has observed hundreds of squirrels in nature and yet, even for her, when the undergraduate students told her what they had witnessed, she said, “No, I’m not sure what you’re referring to.”
Then she watched the video.
‘We saw it everywhere’
“I could barely believe my eyes,” said Wild, a postdoctoral research fellow in the UC Davis Environmental Science and Policy department. “From then, we saw that behavior almost every day. Once we started looking, we saw it everywhere.”
The team said through videos, photos and direct observations at the park, the authors documented California ground squirrels of all ages and genders hunting, eating and competing over vole prey between June 10 and July 30.
The squirrels’ carnivorous summer behavior peaked during the first two weeks of July, coinciding with an explosion in vole numbers at the park reported by citizen scientists on the app iNaturalist.
Researchers said it suggests squirrels’ hunting behavior emerged alongside a temporary increase in the availability of prey. The scientists didn’t observe the squirrels hunting other mammals.
“The fact that California ground squirrels are behaviorally flexible and can respond to changes in food availability might help them persist in environments rapidly changing due to the presence of humans,” Wild said.
Smith said many species, including the California ground squirrel, are “incredible opportunists.” “From raccoons and coyotes to spotted hyenas and humans, the flexibility these mammals apply to their hunting strategies help them change and adapt with the human landscape,” Smith said.
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