I wonder whether it would recognize a squirrel's distress or warning call. Our next-door neighbor once asked me what that "quacking sound" coming from somewhere in the trees was; she thought it was a bird and was astonished when I said it was a squirrel (and pointed out where he was).
There are two cardinals who frequent the cherry tree in our backyard and in the evenings we use their chirping as a sign to tell us when Fraidy Cat has arrived looking for food—when the chirping suddenly becomes near-constant, 99% of the time it means Fraidy is out there.
