You may never look at squirrels the same way again!
A new study from the University of Wisconsin-Eau Claire and the University of California suggests that California ground squirrels not only eat nuts and seeds but also hunt, kill and eat other rodents.
The study offers the first documentation of the species actively preying on other live vertebrates, including shocking footage of the squirrels hunting, killing and eating voles.
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Published in the Journal of Ethology, the study fundamentally changes our understanding of ground squirrels. It suggests that what was considered a herbivorous species actually is an opportunistic omnivore and more flexible in its diet than previously assumed.
Researchers made their discovery during the 12fth year of a long-term study on the California ground squirrel population carried out at Briones Regional Park in Contra Costa County, California. 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 Dr Jennifer E. Smith, an associate professor of biology at University of Wisconsin-Eau Claire, who led the study.
'We had never seen this behaviour 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.'
Opportunistic feeders
The squirrels' carnivorous eating habits peaked during the first two weeks of July, which conicided with an explosion of vole numbers in the park.
According to the researchers, this suggests their hunting behaviour emerged alongside a temporary increase in the availability of prey.
Sonja Wild, an author of the study, said, “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."
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 help them change and adapt with the human landscape.
Several questions about the carnivorous behaviour remain unanswered, including how widespread the hunting behaviour is among squirrels, whether and how it is passed down from parent to pup, and how it effects ecological processes.
The authors will be returning 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.