We have tons of squirrels around here, and since I have so many birdfeeders I have a popular backyard for neighborhood rodents. My kitty goes nuts when he sees squirrels or chipmunks out back - he plasters himself up against the window, starts pawing at the glass, pacing back and forth, and making the little "machine gun" noise that was mentioned on another thread. The squirrels could care less about him, though - they know he's not a threat