Watch a cat locked onto a bird on the other side of the glass and you will see the whole body tighten, tail low, pupils wide, ears forward, and then the jaw starts moving in that rapid, stuttering ...

You might notice your cat pause at the window, focus on a bird outside, and make a quick clicking or chirping sound. It isn't a meow or a growl. It's a behavior known as chattering, and it's fairly ...