Swallow (Bird)

The swallows, martins, and saw-wings, or Hirundinidae are a family of passerine songbirds found around the world on all continents, including occasionally in Antarctica. Highly adapted to aerial feeding, they have a distinctive appearance. The term "swallow" is used as the common name for Hirundo rustica in the UK[1] and Ireland.[2] Around 90 species of Hirundinidae are known, divided into 21 genera, with the greatest diversity found in Africa, which is also thought to be where they evolved as hole-nesters.[3] They also occur on a number of oceanic islands. A number of European and North American species are long-distance migrants; by contrast, the West and South African swallows are nonmigratory.