(KRON) -- Squirrels in the East Bay seemed to have acquired a taste for blood, according to new published research. Scientists observed for the first time California ground squirrels "of all ages and genders" actively hunting and eating voles for a period of several weeks over this summer.
Published in the Journal of Ethology, researchers from the University of California, Davis and the University of Wisconsin-Eau Claire shared extraordinary evidence of the carnivorous squirrels. Out of 74 observed interactions between California ground squirrels and California voles that took place June 10 through July 30 at Briones Regional Park in Contra Costa County, 42% involved active hunting.
"Once we started looking, we saw it everywhere," UC Davis researcher Sonja Wild said in the study's announcement. "We saw that behavior almost every day."
Video shared by Wild on YouTube (viewer discretion advised) shows instances of the East Bay ground squirrels chasing the vole prey and eating them.
Although this is the 12th year of the Long-term Behavioral Ecology of California Ground Squirrels Project, it is the first time the behavior was seen. Scientists said that the peak of the carnivorous summer behavior was during the first two weeks of July 2024.
"Squirrels are one of the most familiar animals to people," the lead author of the study and associate professor of biology at UW-Eau Claire, Jennifer E. Smith, said. "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."
Data suggested to the scientists that the rise in the squirrels' hunting behavior coincided with the temporary increase in the availability of vole prey. "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.
Scientists said they are still unsure how widespread the behavior is among squirrels, how it is learned and how it affects ecological processes.
The squirrels were not observed hunting any mammals other than voles.