(2059) Stercorarius pomarinus pomarinus.
THE POMATORHINE SKUA.
Lestris pomarinus Temm., Man. d'Orn.,p.514 (1815) (Arctic Europe). Stercorarius pomatorhinus. Blanf. & Oates, iv, p. 330.
Vernacular names. None recorded.
Description. (1) Whole plumage brown; almost black on the head, tail and primaries, rather paler below; the primaries are white-shafted. (2) The second phase is very similar to the brown and white phase in Richardson's Skua but the white collar is much narrower and both this and the sides of the head are more strongly glossed with golden-yellow; there is almost always, if not invariably, a broad pectoral band of deep brown, the flanks and sides of the breast are often much barred with brown and there are sometimes traces of dark bars on the abdomen, probably in younger birds only.
Colours of soft parts. Iris brown; bill horny-brown, the cere bluish-grey; legs and feet black.
Measurements. Wing 347 to 380 mm.; tail 170 to 207 mm.; tarsus 48 to 56 mm.; culmen 35 to 40 mm. Females are about as big as males.
Young birds are very like those of Richardson's Skua.
Nestling pale sooty-brown, with a tinge of rufous.
Distribution. The Western Palaearctic Region. A single specimen of this fine Skua was obtained by Col. Tickell at Moulmein. The bird from Eastern Siberia has been separated as S. p. camtschatica Pallas.
Nidification. The Pomatorhine Skua breeds from early June to the middle of July and apparently singly or in very small groups, though one large colony is said to breed North of Sukertoppen in Greenland. The eggs are laid in depressions in the moss on the tundras and twenty-three authenticated eggs measure 63.6 x 45.0 mm : maxima 72.6 X 44.9 and 71.0 x 47.*0 mm ; minima 57.2 X 48.6 and 66.1 x 41.5 mm. They differ from those of Richardson's Skua not only in being larger but also in being comparatively much broader. The colour of the few known seems to be of the brown type of Skua's egg.
Habits. Those of the genus.