Squirrels are known for stuffing their cheeks with nuts, but they can be carnivorous as well. It’s just that recorded cases of squirrels hunting and eating other live creatures are rare. Very few species have been known to do so.
But now, scientists have discovered evidence of a type of squirrel in California displaying carnivorous behaviors.
California ground squirrels are native to the state’s grasslands, and they were observed hunting, killing, and chowing down on voles.
The research was part of the Long-Term Behavioral Ecology of California Ground Squirrels Project at Briones Regional Park in Contra Costa County.
The project looked at how California ground squirrels altered their behavior as a response to changes in the environment, such as an increase in the local population of voles.
Vole infestations have been detected in some parts of northern California. At the research site, there were a higher number of voles than average over the last decade.
California ground squirrels are usually considered to be herbivores or granivores that eat primarily plants and seeds. But the new findings provide proof that the species has been actively preying on other live vertebrates.
“This research radically changes our perception of squirrels, one of the most familiar mammals in the world,” said Jennifer Smith, the lead author of the study and an associate professor of biology at the University of Wisconsin-Eau Claire.
“In the face of human insults, such as climate change and drought, these animals are resilient and have the potential to adapt to live in a changing world.”
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Scientists observed the squirrels’ meat-eating behavior from June 10 to July 30. They used live traps to capture, mark, and release the squirrels every two weeks. Each animal was labeled with two identification tags and a fur mark with dye so they could be tracked.
The research team divided the squirrels into three groups and watched them in their natural habitat. They documented 74 interactions between the squirrels and voles.
Overall, 42 percent of the encounters involved squirrels hunting and consuming the voles. The squirrels included both male and female juveniles.
The study also uncovered new and previously unrecorded social interactions between squirrels and voles. Some were positive, including playing, greeting, and foraging. Others were more competitive, including chasing, pushing, pouncing, and biting.
The results of the study suggest that squirrels should be categorized as opportunistic omnivores. When there is a plentiful supply, they are willing to hunt and consume live prey.
Protein is necessary for squirrels to thrive. Hunting voles probably gives them a better, more accessible source of protein than seeds.
An animal utilizing a resource made available to them is a phenomenon called dietary plasticity. If an animal does not adapt to use the resource, another species will snatch it up.
Initially, this discovery may seem concerning, but experts say that such a dietary change is pretty normal in animals.
Plus, having new predators will help keep vole numbers under control. Additionally, it offers some insight into the adaptability of different squirrel species and other mammals.
The research was published in the Journal of Ethology.