(2064) Larus genei.
THE SLENDER-BILLED GULL.
Larus genei Breme, Rev. Zool., 1839, pt. i, p. 321 (Red Sea,. Africa). Larus gelastes Blanf. & Oates, iv, p. 303.
Vernacular names. None recorded.
Description. - Breeding plumage. Mantle pale dove-grey ; first primary white with black outer web and small tip ; second primary white with broader black tip and black edge to inner web ; the black increases on each succeeding feather and the white becomes greyer until the innermost primary is grey with a broad black terminal baud and just . a tiny extreme tip of grey; outer secondaries darker grey than the back; remainder of plumage white with a beautiful rosy tinge everywhere.
Colours of soft parts. Iris pale yellow; bill deep crimson-red , eyelids bright red ; legs and feet bright dark red.
Measurements. Wing 280 to 316 mm.; tail 119 to 144 mm.; tarsus 47 to 55 mm.; culmen 38 to 46 mm.
In Winter there is no change of plumage but the rosy tinge is less strong.
Young birds have no rosy tinge; the inner wing-coverts are mottled with brown; the outer primaries are white with brownish-black edges to both webs and brown tips; the outer edge gradually disappears and the inner edge increases until the whole of the inner web is brown and the outer grey; the tail is tipped with brown on all but the two outer pairs of feathers. The bill, legs and feet are pale orange.
Nestling in down. White tinged with buff, especially on the head and mottled with black, these mottlings forming fairly well-defined bars on the head and wings.
Distribution. Breeding throughout the Mediterranean, Caspian, Red Sea, the Corsican Gulf and Mekran coast. It occurs on West Coast of Africa as far South as Senegambia.
Nidification. Within our limits the Slender-billed Gull breeds on the Mekran coast and in Sind but its breeding is irregular and, as Ludlow suggests, possibly dependent on rainfall. In years of comparatively heavy rain the lakes are fresh and not suitable for this salt-water-living Gull but in years of scant rainfall, swamps, such as the Sonmeani Bheel, become low and very brackish and are then resorted to by these Gulls in very large numbers. The nests are thick pads of weeds placed on islands in, or on the shores of, the big swamp and the eggs number one to three. On the Sonmeani Bheel Ludlow found the normal clutch to be three but Cox and Cheesman found many single eggs hard-set on islands in the Persian Gulf. The eggs vary very little. The ground-colour ranges from dead-white to very pale buff, cream or yellowish-stone and only in one egg have I seen a greenish tint. The markings consist of blotches, large and small, of dark brown, blackish-brown or reddish-brown, with secondary markings of violet. Scrolls and lines are unusual in the eggs of this species. Two hundred eggs average 55.75 X 38.65 mm. : maxima 63.4 X 42.0 and 58.0 x 43.1 mm.; minima 51.5 X 39.3 and 56.1 X 36.3 mm.
The breeding-season on the Mekran coast is June and July and on the Persian Gulf islands May and June.
Habits. This Gull keeps entirely to salt water and never wanders far inland. It collects in large flocks some distance out at sea, feeding almost entirely on small fish. It has the usual querulous croak of the family and is a noisy bird when, feeding.