Posted on 12/18/2024 5:45:57 AM PST by Red Badger
A California ground squirrel in Conta Costa County runs with a vole it hunted in its mouth. A study from UC Davis and University of Wisconsin-Eau Claire is the first to document widespread carnivorous feeding of voles by squirrels. Credit: Sonja Wild/UC Davis
Researchers have uncovered that California ground squirrels, once thought to be primarily seed-eaters, actively hunt and eat voles.
This behavior, observed during a long-term behavioral study, suggests these squirrels are more adaptable and omnivorous than previously believed, potentially aiding their survival in changing habitats.
New Insights on Squirrel Omnivorous Diet
California ground squirrels are often seen with cheeks full of nuts, seeds, or grains—a familiar image of a harmless herbivore. However, a groundbreaking study reveals that these squirrels also hunt, kill, and eat voles. Researchers from the University of Wisconsin-Eau Claire and the University of California, Davis, have documented this behavior for the first time, providing the first detailed account of carnivory in ground squirrels.
The study, published today (December 18) in the Journal of Ethology, reshapes our understanding of these animals. Once thought to be strictly granivores, California ground squirrels have proven to be opportunistic omnivores with a far more adaptable diet than previously believed.
Ground Squirrel Eats Vole
A California ground squirrel dines on a vole it hunted in a Bay Area regional park. Credit: Sonja Wild, UC Davis Observational Study and Surprising Discoveries
The observations occurred in 2024 — the 12th year of the Long-term Behavioral Ecology of California Ground Squirrels Project conducted at Briones Regional Park in Contra Costa County. Out of 74 observed interactions with voles between June and July, 42% involved active hunting of these small rodents by ground squirrels.
“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.”
Wild has observed hundreds of squirrels in nature and yet, even for her, when the undergraduate students came in from fieldwork and told her what they had witnessed, she said, “No, I’m not sure what you’re referring to.” Then she watched the video.
“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.”
Squirrel Eats Vole...A California ground squirrel eats a vole it hunted in Briones Regional Park in Contra Costa County. Credit: Sonja Wild, UC Davis
Opportunists Amid Rapid Change
Through videos, photos, and direct observations at the regional 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 of vole numbers at the park reported by citizen scientists on iNaturalist. This suggests the squirrels’ hunting behavior emerged alongside a temporary increase in the availability of prey, the study said. The scientists didn’t observe the squirrels hunting other mammals.
Behavioral Flexibility and Ecological Impact
“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 added that 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 helps them change and adapt to the human landscape.
“Through this collaboration and the data coming in, we’re able to document this widespread behavior that we had no idea was going on,” Smith said. “Digital technology can inform the science, but there’s no replacement for going out there and witnessing the behavior because what animals are doing always surprises us.”
The researchers said many questions remain unanswered, including how widespread hunting behavior is among squirrels, whether and how it is passed down from parent to pup, and how it effects ecological processes. The authors are also excited to return to the field next summer to see what impact, if any, this year’s vole hunting may have on squirrel reproduction compared to the past decade.
Reference:
“Vole hunting: Novel predatory and carnivorous behavior by California ground squirrels” 18 December 2024, Journal of Ethology.
DOI: 10.1007/s10164-024-00832-6
Coauthors include Joey Ingbretson, Mackenzie Miner, Ella Oestreicher, Mari Podas, Tia Ravara, Lupin Teles, and Jada Wahl of UW-Eau Claire and Lucy Todd of UC Davis.
Several coauthors conducted field work during their undergraduate studies. Their work was partly funded by the Ronald E. McNair Postbaccalaureate Achievement Program, Diversity Mentoring Program and Summer Research Experience for Undergraduates. Additional funding sources include the Swiss National Science Foundation and the Vicki Lord Larson and James Larson Tenure-track Time Reassignment Collaborative Research Program.
It’s a ground squirrel. Chipmunks have racing stripes. Ground squirrels are everywhere out West.
We have trapped more ground squirrels in our squirrel trap with dog food than with sunflower seeds.
Big Fing deal. Deer regularly hunt and eat baby birds.
Quit thinking of Disney films as documentary.
“ The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known as marmots (genus Marmota) or prairie dogs, while the smaller and less bushy-tailed ground squirrels tend to be known as chipmunks (genus Tamias).”
I know between Deep South and middle TN and long Lake Michigan I see plenty varieties
Mississippi has no ground squirrels or chipmunks much
But plenty grey and Fox squirrels mostly the latter are orange red and some black
Nashville has no Fox squirrels but plenty grey and ground and chipmunks and marmot
North Michigan where my brother is has all of the varieties and beaucoup black Fox squirrels
I eat tree squirrel but it’s a lot of work for the meat and games is an understatement
In turn, voles (field mice) have been observed scavenging the cadavers of dead animals.
In Nature, NOTHING GOES TO WASTE.......................
Squirrels are part of the rodent family and therefore are closely related to the Rat family.
File this study under the heading: “Duh!”
If this is the idiocy that passes for intelligence at our academic institutions - We are doomed.
“Are the voles simply a food source, or are the squirrels regarding them as competitors for the seeds and nuts, clearing them out like a rival gang?”
In the last ten years I have seen in my neighborhood>>>
—#1 A small common lizard replaced/run out of town, by a new lizard that is 50% larger
—#2 Muscovy ducks that wander around, replaced by Egyptian geese wandering around
Rats have foods they prefer. But will eat anything. Many YouTube videos of NYC rats eating discarded pizza crusts.
https://www.youtube.com/results?search_query=NYC+rats+eating+discarded+pizza+crusts.
Even NYC rats wrestling large pizza crusts up the stairs of subway stations
“File this study under the heading: “Duh!”
😂👍
I guess I need to import squirrels to get rid of my vole population, which is a scourge to my garden and greenhouse. They eat everything and have a voracious appetite. I’ve even had them eat jalapeno peppers down to just the nubs of the plants. Anything to get rid of the little bastards.
Once battery-powered video cameras got small enough to fit inside of a squirrel’s nets (something like 20 years ago), they discovered that a female (tree) squirrel with babies in the nest will raid the nest of a neighboring female (if she also has babies), eat the neighbor’s babies and kill the ones she can’t eat.
Makes for better nutrition for her babies, and less competition.
:)
👊
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