Description
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 are a dirty white. The eyes are brown, the small bill is mainly black, and the legs are brownish-pink. The wing length averages 1.3 cm (4.55 in) and the tail averages 4.8 cm (1.9 in). The sexes are similar in appearance, but juveniles have pale edges to the upperparts and flight feathers. The other subspecies differ from the nominate form as detailed in the table above.
This martin moults early, with adults having completely replaced their feathers by late August. Juveniles moult somewhat later, and their old primary feathers are retained even when the body has mainly adult plumage.
The Pale Crag Martin's flight is slow, with rapid wing beats interspersed with flat-winged glides, and it is more acrobatic than the larger Eurasian Crag Martin. It is a quiet bird; the song is a muffled twitter, and other calls include a trrt resembling the call of the Common House Martin, a nasal vick, and a high pitched twee contact call.
The Pale Crag Martin is much drabber than most African swallows, and confusion is unlikely except with other crag martins or with sand martins of the genus Riparia. It is 15% smaller, paler and greyer than the Eurasian Crag Martin, and has smaller tail spots. It is smaller, paler, and has a more contrasting throat than the Rock Martin. In the far east of its range, the Pale Crag Martin always has lighter underparts than the Dusky Crag Martin. Although only slightly larger than the Sand Martin and Brown-throated Sand Martin, the Pale Crag Martin is more robust, has white tail spots, and lacks a breast band. Separation of similar species in flight may be complicated by the difficulty of judging colours accurately in strong desert light, particularly with juveniles. The fast flight of the Brown-throated Sand Martin also makes identification more difficult.
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