Squirrels are capricious little creatures. And aside from taunting the neighborhood dogs and using your gutters as water slides, it appears they also eavesdrop on bird chatter to gauge their safety.
A new study published in the journal PLOS One concludes grey squirrels use the sounds of nearby birds to infer the absence of predators.
Researchers from Oberlin College played several recordings for squirrels in their natural habitat, including the ambient chatter of birds around a feeder and the sound of a red-tailed hawk; a predator.
Understandably, the squirrels went on alert after hearing the hawk sound, displaying what the study calls “vigilance behavior.” This could include freezing, looking around more often or standing up.
Hawks v. birds
However, the researchers found squirrels who heard bird chatter some time after the hawk sound “expressed significantly lower and more rapidly declining levels of vigilance behavior than those exposed to ambient noise.”
According to the researchers, bird sounds are “likely to indicate safety because such sounds are generally given when imminent threat has not been detected.”
So after the indicated presence of a threat in the red-tailed hawk, the squirrels were more likely to relax if they thought other species around them were relaxing too.
What this means
This seems like a pretty natural thing to humans — we often glean social cues from the behaviors of people around us. But in the animal kingdom, research has usually focused on different species using alarm calls or other indicators of concern as a way to gauge safety. Using the opposite, in this case, the relaxed chatter of unthreatened birds, is somewhat novel.
“A few studies have demonstrated eavesdropping on non-sentinel calls within co-foraging groups as an index of safety,” the study reads. “However, to our knowledge, our study is the first to demonstrate eavesdropping on non-sentinal calls outside of a co-foraging group association, indicating that eavesdropping on cues of safety may be more widespread than previously recognized.”
CNN has called the authors of the study for more comment.
This kind of research can tell us more about how different species communicate and interact within their multi-species communities. It can’t, however, tell you why they love to cause a ruckus right outside your house at all hours.