The California floor squirrel appears harmless. A well-known sight to hikers, the plump rodent can usually be seen contentedly chewing on grasses, seeds and berries.
However in response to new analysis revealed on Wednesday within the Journal of Ethology, wildlife biologists have documented a fierce characteristic of the creature: It’s a dedicated carnivore, looking and feasting on unfortunate little voles.
Like a rodent model of the notoriously violent 1969 movie “The Wild Bunch,” intensive video footage recorded at Contra Costa County’s Briones Regional Park presents repeated proof of the squirrels’ savagery.
Squirrels chase the voles, then catch and pummel them till they’re a bloody pulp. Like cats, the squirrels generally let the mortally wounded creature limp off. Then they pounce once more. Even because the vole squirms, clinging to life, they take a chunk.
It’s been recognized that California floor squirrels gained’t go up a simple meal of meat. Prior analysis discovered clues of ingested voles, in addition to quail eggs, bugs and shellfish.
However the brand new research, led by the College of Wisconsin-Eau Claire and UC Davis scientists, is the primary to chronicle widespread predatory habits.
“This was shocking,” mentioned lead creator Jennifer E. Smith, an affiliate professor of biology at UW-Eau Claire who with Sonja Wild of UC Davis leads the Lengthy-term Behavioral Ecology of California Floor Squirrels Undertaking.
“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,” she mentioned.
With its rolling, grassy hills and secluded, shady canyons, Briones is heavenly habitat for floor squirrels.
Prolific and plentiful, the squirrels are intriguing as a result of they’ve a bigger and way more complicated social construction than different squirrel species, in response to Smith.
The habits of two completely different floor squirrel populations is the main target of analysis by college and college students from UC Davis, Wisconsin and different establishments.
Researchers witnessed California floor squirrels looking and consuming voles at Briones Regional Park in June and July 2024. Sonja Wild, UC Davis
Dubbed Crew Squirrel, the researchers comply with particular animals 12 months after 12 months, gathering intensive knowledge on the social and organic histories of many particular person creatures throughout their lives.
They analyze recordings of alarm calls. They research squirrel poop to find out about intestine well being. They witness tense rattlesnake vs. squirrel standoffs.
In 2024, one thing uncommon occurred. Components of California skilled an uncommon explosion within the abundance of voles.
Defenseless bundles of fur, voles are small and pudgy, with quick rounded ears, a rounded head and stressed power. They’re engineers, digging burrows which flip soil and transfer seeds. Energetic night time or day, they’re pushed by an infinite urge for food and the ever-present have to feed their offspring. Voles might produce as many as six or seven broods a 12 months.
Scurrying by way of a meadow in broad daylight is dangerous for voles, the researchers discovered.
By movies, images and direct observations on the regional park, they documented floor squirrels looking, consuming and competing over vole prey between June 10 and July 30. The squirrels’ carnivorous summer season habits peaked throughout the first two weeks of July, coinciding with an explosion of vole numbers on the park reported by citizen scientists on iNaturalist, a free app the place customers have recorded hundreds of thousands of observations of untamed animals and crops.
Scientists witnessed floor squirrels looking and consuming voles in June and July 2024 in Briones Regional Park.
The squirrels didn’t appear fascinated with looking different small mammals.
Watching video, “I could barely believe my eyes,” mentioned Wild. “From then, we saw that behavior almost every day. Once we started looking, we saw it everywhere.”
The research adjustments our understanding of floor squirrels — suggesting that what was thought of a grain-eating species truly is an opportunistic omnivore, say researchers.
It’s recognized that many different species, together with raccoons, coyotes and people, are versatile of their weight loss plan and habits.
The brand new research exhibits that the California floor squirrel may reply to a surge within the availability of prey, in response to the research.
“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,” mentioned Wild.
Different questions stay unanswered. As an example, it’s not recognized whether or not the looking habits is widespread, whether it is handed down from father or mother to pup, and the way it impacts the bigger ecology of the pure panorama.
The researchers plan to return to Briones subsequent summer season to see what influence, if any, this 12 months’s vole weight loss plan had on the numbers of squirrels.
By then, nevertheless, the squirrels might have grow to be another person’s dinner. Hungry snakes, weasels, hawks and eagles depend on them for sustenance.
Floor squirrels are predators. However, like voles, they’re additionally prey.
