What is a "house martin"?

A house martin is a small migratory bird found across Europe and parts of Asia and Africa. With its sleek and agile build, the house martin is known for its aerial acrobatics, gracefully swooping and darting through the air as it catches insects on the wing. It has a distinctive appearance, featuring a glossy blue-black plumage on its back, contrasting with a white underbelly. The house martin is particularly recognized for its skill in building intricate nests made of mud, which are attached to the sides of buildings and other structures. These nests provide shelter and protection for their eggs and young. House martins are social birds, often nesting in colonies, and they are known for their cheerful twittering calls.