Shift of song frequencies in response to masking tones

► We investigated song plasticity in wild black-capped chickadees. ► We presented males with tones that either overlapped their songs (masking) or were outside their singing range (control). ► Chickadees shifted their song frequencies more quickly in the presence of masking tones as compared to control tones. ► Chickadees can modulate their singing behaviour in response to the sound environment.