Swallows and martins

Swallows and martins (Hirundinidae)
Mostly small, elegant, aerial species with long, tapered wings, forked tails (often with elongated outer feathers) and small bills but wide mouths, for catching insects in flight. There are three regular species in the UK plus some rare visitors, and many species worldwide. They tend to fly lower and slower than swifts but different species exploit different levels of air space and different sizes of aerial insects. Unlike swifts, they perch frequently on wires and (less often) trees and may be seen on roofs, sometimes on the ground.