The North American race, Barn Swallow differs from the European form in having redder underparts. The resident African Rufous-breasted Swallow H. r. semirufa also has red underparts, and is sometimes considered a separate species, Hirundo semirufa.
The term swallow is often also used to refer more widely to various members of the Hirundinidae family.
Swallows are somewhat similar in habits and appearance to the other aerial insectivores, such as the related martins and the unrelated swifts (order Apodiformes). Swifts are larger than Swallows and dark except for a plain white throat. House Martins have white faces, a conspicuous white rump, and are smaller.
They have dark blue upperparts, white underparts and a small patch of red on their throats.
Barn Swallows build neat cup-shaped nests lined with mud collected in their beaks, They normally nest in accessible buildings such as stables.