It turns out that squirrels have their own special twitter to assess if they are in danger. The rodents appear to use the idle conversation of multiple bird species to assess if they are safe to come out of hiding after being threatened.
As reported in the journal PLOS ONE, researchers studied the behavior of 54 wild eastern gray squirrels (Sciurus carolinensis) located in parks and residential areas in Ohio. The scientists simulated threats to these animals by playing a 1-to-3-second recording of a red-tailed hawk (Buteo jamaicensis), a bird of prey that hunts squirrels and small birds alike.
This “threat” was then followed by 30 seconds of silence before a second recording was played. The team had two recorded follow-ups to the predator call. One contained a multi-species songbird “chatter” and the other was ambient sound lacking bird calls. The researchers played these three minutes following the first recording and monitored the squirrels' behavior during this time window.
All squirrels showed more predator vigilance behaviors. After all, from their point of view, a red-tailed hawk had just flown by, so they were standing, freezing, looking up, fleeing, etc. Being good cautious squirrels. They were looking bewildered and confused as if they were wondering if they left the oven on. You know, squirrel behavior.
The interesting find is that those that heard the recording with the chattering birds exhibited fewer of these behaviors. But that’s not all. These squirrels returned to a normal level of vigilance faster than those who listened to the recording that had ambient noise but no songbirds.
“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 authors explained in a statement.
The team argues that not many studies have looked at how animals use non-alarm signals from the "leisure" communications of other species. These background noises could be interpreted as an “all-clear” signal and maybe this type of behavior is more widespread than previously thought.