Both male and female Barn Swallows sing a “twitter-warble” song during courtship and egg-laying, with a long series of continuous warbling sounds followed by up to a dozen rapid, mechanical-sounding whirrs. The song can last 4–20 seconds and is often introduced and followed by a chirp.
Barn Swallows give a cheep call when threatened, and when predators approach too close to a nest site, a churee whistle will send adults diving at the threat. In colonies, this call may flush all of the adults from their nests and set them circling above a predator. Males apparently may foil their mate’s attempt to copulate with another male by giving a “fake” alarm call. Both sexes also give an agitated, stuttering call when chasing other Barn Swallows away from nest sites or mates.