It provides aerodynamic benefits, allowing them to change direction quickly and efficiently while chasing insects in flight. The deep fork creates a reduction in drag and enables rapid acceleration, making it easier for them to catch their prey.
The elongated outer tail feathers also help them maintain stability and balance during aerial acrobatics, allowing them to perform sharp turns and twists without losing control.
Additionally, the forked tail may play a role in communication among barn swallows. The movement of the tail during flight can convey different signals to other individuals within the flock, facilitating social interactions and group coordination.