Researchers from Oberlin College in the US noted that casual chatter by birds post a predator call, helps squirrels decide whether it is the right time to come off a high-alert state.
This is proof that one species under threat listens to another to make decisions about its own survival, according to the study published in the journal PLOS One.
The researchers observed how 54 wild Eastern gray squirrels (Sciurus carolinensis) in public parks and residential areas in Ohio, US responded to threat by playing back a recording of a red-tailed hawk’s call (Buteo jamaicensis) -- a bird preying on both squirrels and small birds.
This was followed by a playback of either multi-species songbird bird chatter, or ambient sounds without bird calls, and the researchers monitored the behaviour of each squirrel for three minutes.
They found that all squirrels showed an increase in vigilance by exhibiting behaviours such as freezing, looking up, or fleeing, once they heard the hawk’s call.
However, those squirrels that listened to the playback of casual bird chatter returned to normal level of alertness much quicker than those that did not hear the birds’ chirps, the study found.
“We knew that squirrels eavesdropped on the alarm calls of some bird species, but we were excited to find that they also eavesdrop on non-alarm sounds that indicate the birds feel relatively safe. Perhaps in some circumstances, cues of safety could be as important as cues of danger,” the researchers added.