A bird dog is a gun dog used to hunt or retrieve birds.

The term has since been adopted to refer to:

• A man who steals another man's girlfriend or date, as in the The Everly Brothers's song "Bird Dog", possibly referring to slang terms for women as chicks and other bird-related terms.
• The O-1 Bird Dog, an airplane named for its use, similar to that of bird dogs, in scouting the area (reconnassiance).