Even the most common of species can surprise us. The California ground squirrel (Otospermophilus beecheyi), abundant throughout the western United States, has long been thought to be ‘granivorous’, with a diet consisting mainly of seeds, nuts and fruits. But recently, scientists have discovered that these squirrels like the taste of fresh meat.
The researchers observed the squirrels actively hunting California voles (Microtus c. californicus), a species of rodent whose boom-and-bust population size was at a ten-year-high at the time of the study. The squirrels would chase and kill the voles, before feasting on the carcasses.
"Whereas there has been some evidence here and there of other species of squirrels hunting birds or mammals on occasion, our study is the first to document the widespread occurrence of California ground squirrels hunting, killing and eating the flesh of California voles,” Dr Jenn Smith tells BBC Wildlife.
“This behaviour appears to be novel to us, as we have never observed it before in our previous eleven years of this long-term study.”
It is thought that the vole population boom, and therefore their increased availability to the squirrels, may be the reason the squirrels started to prey on them.
Male and female squirrels of all ages were observed hunting, and they almost always hunted solo. They were not, however, always successful. Around half of hunts ended in failure for the squirrels, in some cases because the voles fought back. Vole-hunting, it seems, is not without its risks.
It is not yet known how the squirrels learn to hunt. They may learn individually through trial-and-error. Alternatively, they may learn socially, by observing the hunting behaviour of others.
The researchers hope to study this by looking at whether hunting behaviour can be mapped onto the squirrels’ social networks. If hunting behaviour spreads from friend to friend, it is likely that they are learning to hunt through observation.
The meat-eating behaviour of California ground squirrels is exciting not just because it shows that squirrel diet is more flexible than previously thought – which might help them better adapt to human-induced habitat change – but also because of the direct impact that a carnivorous diet might have on the squirrels. "Perhaps the most exciting aspect of this research will be to see how this energetically rich meat influences the survival and reproduction of our ground squirrel study subjects,” Dr Smith says.
Main image: California ground squirrels hunting voles/Sonja Wild, UC Davis
More wildlife stories from around the world
- Researchers just tracked a huge animal through the Peruvian Andes – what they found could be critical
- A rare, formidable-looking creature is clinging to life in California's High Sierra
- Humans didn't want to go into this mysterious jungle in Asia, so they sent a drone in instead
- Deep-sea scientists just filmed something enormous swimming over the seafloor in Chile
