Pale crag martin to do so, it would cast doubts on their specific distinctness. There are several subspecies differing in plumage shade or size, although the differences are clinal, and races interbreed where their ranges meet. The pale crag martin of the nominate subspecies "P. o. obsoleta" is 12–13 cm (4.7–5.1 in) long with light brown upperparts, becoming paler on the lower back, and a short square tail that has small white patches near the tips of all but the central and outermost pairs of feathers. It has a pale grey throat, upper breast and underwing coverts, and the rest of the underparts
Self colour the tip. The term can also be used to distinguish between colour and pattern; patterns are unpigmented areas with pink skin and white hair. In this definition, an animal has only one self-colour, which is the sum effect of all the genes acting on the pigment. For example, a black and tan piebald Dachshund has patterns (piebald) and self-colours (black and tan). Self colour A self colour refers to the top coat colouration of several domestic animals, such as dogs, pet rodents and cats. It refers to hairs of a uniform shade, with no banding or tipping of another colour.