Sonja Wild / UC Davis
California ground squirrel runs with a rat it hunted in its mouth
In the verdant hills of California’s Briones Regional Park, squirrels are not what they seem. These familiar rodents, known for eating nuts and seeds, have been seen hunting and decapitating rats, in a horrific dietary adaptation.
Instead of just stuffing their cheeks with berries, nuts or seeds, California ground squirrels are now known for hunt, kill, decapitate and consume rats, a related species of rodent.
In a new one, published on Wednesday in Journal of Ethologyscientists claim that this behavior could be a sign of resistance to environmental pressures.
“This was shocking“, states the main author of the study, Jennifer E. Smithprofessor of biology at the University of Wisconsin-Eau Claire, in a . “We have never seen this behavior before.”
Most people are very familiar with squirrelsused to seeing animals on their streets or in their backyards.
Even more familiar is Jennifer Smith, leader since 2013 of the California Ground Squirrel Long-Term Behavioral Ecology Project, which monitors squirrel genetics, social behavior and physiological responses to stress in the San Francisco Bay Area.
But even with their in-depth knowledge of these rodents, says , only this year has their research team observed ground squirrels at actively seeking and eating carne.
The initial discovery was made by university researchers, who returned from the field site in Briones Regional Park earlier this year with videos of the squirrels’ behavior to show their incredulous supervisors.
“At first, we questioned what was going on,” explains Smith. “But watching the videos It was amazing and changed my perspective about a species that I spent the last 12 years of my life studying.”
Smith and his team documented 74 interactions between ground squirrels and rats between June and July. In 42% of interactions, squirrels hunted the smallest rodents.
“From then on, we saw this behavior almost every day,” he says. Sonja Wilda postdoctoral researcher at the University of California, Davis, who co-directs the project with Smith, in the release. “When we started looking, we saw him everywhere“.
Although they are mostly vegetarians, it has long been known that squirrels occasionally consume insectseggs from small birds or meat left aside by humans. But direct study of squirrel hunting behavior remains rare.
In most cases recorded in the study, a single squirrel chased a rat in an open field.o, instead of waiting or hunting in groups. Sometimes, with a chasing movement and a jump, the squirrel grabs the rat, holds it with its front paws, bites its neck and removes its head.
Then the squirrel plucked the rat’s hair to expose the cartilagethe meat and organs, or ripped the meat directly from the trunk.
The study authors suggest that this dietary change is a response to a expanding rat population.
Using reports from citizen scientists on , an app that allows users to upload photos of spotted plants and animals, researchers found that the abundance of rats in the state was seven times greater this year than the ten-year average, and sightings were particularly high in Briones Regional Park.
“What is most impressive and incredible is how quickly they changed their behavior to this local increase in rat abundance,” Smith tells CNN’s Julianna Bragg.
“It’s a wonderful way to capitalize on a very abundant resource to provide enough sustenance for many squirrels to use,” says John Koprowskia wildlife biologist at the University of Wyoming who was not involved in the study, told .
Squirrels of all ages and sexes participated in rat hunting, an indication that this dietary flexibility is widespread in the species and may serve as a crucial survival mechanism in response to fluctuating environmental conditions, especially in areas with high human populations.
“In the face of human aggressions, such as climate change and droughtthese animals are resilient and have the potential to adapt to live in a changing world,” concludes Smith.
