"Dr. Greene, working with a student, has also
found that "squirrels understand 'bird-ese,'
and birds understand 'squirrel-ese.' " When
red squirrels hear a call announcing a
dangerous raptor in the air, or they see such a
raptor, they will give calls that are acoustically
"almost identical" to the birds, Dr. Greene said.
(Researchers have found that eastern
chipmunks are attuned to mobbing calls by the
eastern tufted titmouse, a cousin of the
chickadee.)..."
http://mobile.nytimes.com/2015/05/19/science/decoding-the-cacophony-of-birds-warning-calls.html
