Killer squirrels of California shock scientists with their 'vole' diet; all you want to know

Squirrels are known for their love for nuts, seeds and fruits, and it is hard to imagine their predatory side. But in a surprising behavior, squirrels in California were observed to be hunting and eating voles (small rodents) for the first time, a behavior that was never seen in the species ever before, and documented in a study published in the Journal Of Ethology.

This may seem like an episode from a sci-fi thriller, but it turns out that this behavior is for real, but may only be seasonal, particularly during the first two weeks of July when voles population is on peak.

“We had never seen this behavior before,” said head author Jennifer E. Smith, an associate professor of biology at UW-Eau Claire, which conducted the study in collaboration with UC Davis. The observation was made in the months of June and July 2024 during the Long-term Behavioral Ecology of California Ground Squirrels Project at Briones Regional Park in Martinez California. Out of the 74 interactions between ground squirrels and voles observed during that time, 42% involved the squirrels hunting the voles.

The videos and photos of ground squirrels across all ages and genders hunting, eating and competing over voles during the period were observed.

What squirrels usually eat

Squirrels aren't known for being carnivorous and they are usually considered granivorous or a species that eat grains for sustenance.

However, some squirrel species may add insects, bird eggs and frogs to their diet. But, they were never earlier observed preying on voles.

“In our twelve years of conducting observations on hundreds of squirrels, we had never observed any incidents of vole hunting before this summer,” Sonja Wild, a UC Davis researcher who collaborated on the study told Popular Science. “It is therefore plausible that hunting is innate in these squirrels to an extent.”

Considering their hunting peak during initial two weeks of July coinciding with the rise in vole population, it can be concluded that this predatory behavior may be prompted by a temporary increase in prey species, as per scientists as they didn't hunt 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,” said Wild.

Interesting facts about squirrels

As per Live Science, squirrels have an omnivorous diet and in addition to eating plant-based food, they also include eggs, small insects, caterpillars, small animals and even young snakes, in their diet.

Squirrels are known to be hoarders and they have their stock full with nuts, seeds and other such foods for the colder months when these supplies are scarce.

Squirrels have four teeth in the front which witnesses continuous growth throughout their lives. This makes sure their teeth don't wear down from gnawing on nuts and other objects.

Squirrels sometimes bury their acorns but forget after putting them and these become oak trees later.