The barn swallow (Hirundo rustica) is a migratory passerine bird, recognized as the most widespread species of swallow in the world. It is a distinctive bird with blue upperparts and a long, deeply forked tail, known for its graceful flight and agile maneuvers. The adult male of the nominate subspecies is 17–19 cm in length, including elongated outer tail feathers, and has a wingspan of 32–34.5 cm. It is adorned with a rufous forehead, chin, and throat, which are set apart from the off-white underparts by a broad dark blue breast band. The outer tail feathers are elongated, contributing to the iconic "swallow tail."
The barn swallow can be identified by its steel blue upperparts, a rufous face, and a dark blue breast band that separates the rufous from the off-white underparts. The deeply forked tail is a key characteristic, with a line of white spots across the upper tail's outer end. Females resemble males but have shorter tail streamers and less glossy blue coloring. Juveniles are browner with paler rufous faces and whiter underparts, lacking the adult's long tail streamers.
