
Martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding. Martins hunt insects on the wing by using their slender streamlined body, and long pointed wings, which allows great maneuverability and endurance.
It is believed that this family originated in Africa as hole-nesters; Africa still has the greatest diversity of species. Martins have short bills, but strong jaws and a wide gape. Their body length ranges from about 10-24 cm (3.9-9.4 in) and their weight from about 10-60 g (0.4-2.1 oz). The wings are long, pointed, and have nine primary feathers. The tail has 12 feathers and may be forked, indented, or square-ended. A long tail increases maneuverability, and may also function as a sexual adornment, since the tail is frequently longer in males. The legs are short, and their feet are designed for perching rather than walking, as the front toes are partially joined at the base, causing the bird to display a waddling gait.
The most common plumage is glossy dark blue or green above and plain or streaked underparts, often white or rufous. Species which burrow or live in dry or mountainous areas are often unglossed brown above (eg Sand Martin and Crag Martin). The sexes show no, or only limited, sexual dimorphism, with longer outer tail feathers in the adult male probably being the commonest distinction where one exists.



