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
Colour-sided Colour-sided Colour-sided is a colour pattern of domesticated cattle. It is sometimes called lineback It consists of a dark body colour, with white finching along the spine, white under the belly, and often white also over the tail, head and legs. The ears, nose and feet are generally dark. The pattern may occur in many breeds, but some breeds are consistently colour-sided, including English Longhorn cattle, Irish Moiled cattle, Randall cattle, Riggit Galloway cattle and Lineback cattle. The dark colour may be any solid colour such as black, red or brindle. An extreme pale form of the colour-sided pattern is