H. r. rustica in Denmark
The Barn swallow (Hirundo rustica) is the most widespread species of swallow that can be found worldwide. A distinctive passerine bird with blue upperparts, a long, deeply forked tail and curved, pointed wings, it is found in Europe, Asia, Africa and the Americas. The barn swallow is the national bird of Estonia. According to The Atlas of Southern African Birds, this species is undergoing a decrease in significant part of Europe <ref><ref>; however, this decrease is not rapid enough to be considered a “vulnerable species“ based on the criterion used to determine species in danger of extinction <ref><ref>.