The discovery of this behaviour left scientists shocked. (Image: Sonja Wild, UC Davis)
Shocking new footage has captured a species of squirrel hunting other animals for the first time, suggesting they may be evolving to become opportunistic omnivores.
New , published on Wednesday in the Journal of Ethology, caught ground squirrels on camera hunting, killing, and then eating voles, a relative of hamsters and lemmings, with gruesome images showing the feasting on the carcasses.
The study, which is part of the at Briones Regional Park in Contra Costa County, examines how the species changes its behaviour in response to environmental changes.
The area has seen an increase in the local vole population and despite the native squirrels once being considered “granivorous” animals, i.e. fed on grain, believe they have developed a taste for meat.
Dr Jennifer E. Smith, an associate professor of biology at University of Wisconsin-Eau Claire who led the study, said the discovery was “shocking”.
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The squirrel species had been considered granivorous (Image: Sonja Wild, UC Davis)
Researchers said the vole hunting was ‘never-before-encountered-in-science behavior’ (Image: Sonja Wild, UC Davis)
“We had never seen this behavior before,” she continued. “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,” Dr Smith added.
Researchers had been observing the creatures at California’s Briones Regional Park in Contra Costa County between June 10 and July 30, and were flabbergasted by the rodents’ aberant behaviour.
California ground squirrels of all ages and genders were reported hunting, eating, and competing between themselves for vole prey.
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Scientists will return to the park next summer to observe the impact on voles and the squirrels themselves. (Image: Sonja Wild, UC Davis)
74 interactions with voles were observed, 42% of which involved active hunting of voles by ground squirrels.
These carnivorous eating habits peaked in the first half of July, just when the number of voles in the park markedly increased.
Researchers believe this suggests their carnivorous behaviour emerged alongside a temporary increase in the availability of prey.
Sonja Wild, an author of the study, said the fact that the species is “behaviorally flexible and can respond to changes in food availability might help them persist in environments rapidly changing due to the presence of humans”.
But scientists have been amazed by the sudden behavioural shift, with Dr Wild admitting she could “barely believe my eyes”.
“We saw that behaviour almost every day,” she said, adding: “Once we started looking, we saw it everywhere.”
Scientists are now working to establish how widespread the behaviour is among squirrels, how and whether it’s passed down from parent to their young, and its impact on ecological processes.
The team is planning to return to Briones Regional Park next summer to see if it has resulted in a long-term impact on both the squirrels and the voles.