By Jennifer Copley (Last Updated 16 July 2011)
According to zoologist and ethologist Desmond Morris, the chattering sounds that a cat makes when she sees a bird through the window are thought to be a vacuum activity. Vacuum activities occur when the cat is unable to fulfill her natural hunting proclivities.
When a cat sees a bird or other prey animal that she can’t get to, she tenses her body and chatters her teeth as a substitute for delivering the killing neck bite. This action likely represents a combination of excitement at seeing an enticing prey animal and frustration at having the hunting drive thwarted. Playing with a cat using toys that simulate prey (such as a fishing pole toy with a cloth mouse or feathers at the end of a string) enables her to practice her hunting skills without killing anything.
Reference: Morris, D. (1987). Catlore. London, UK: Jonathan Cape Ltd.
For more articles on the way cats think and the reasons they do the things they do, visit the main Cat Psychology, Communication, and Behaviour page. For a full list of cat articles, see the main Cats page.