Bill greenish yellow: legs dusky: tarsus one inch four lines: a small knob instead of a back toe: primaries bluish ash, the outer one edged externally with black.
L. tridactylus, Temm. Man. d'Orn. torn. ii. p. 774. Kittiwake, Mont. Orn. Diet, & Supp. Bew. Brit. Birds, vol. ii. pp. 218, & 220. Selb. Illust. vol. ii. p. 493. pl. 94.
Entire length fifteen inches six lines: length of the bill (from the forehead) one inch four lines, (from the gape) two inches one line; of the tarsus one inch four lines; of the tail five inches five lines; from the carpus to the end of the wing twelve inches: breadth, wings extended, three feet one inch four lines.
(Adult in winter). Crown, occiput, nape, and sides of the neck, pale bluish ash, with a few fine dusky streaks before the eyes; forehead, region of the eyes, and all the under parts, pure white: back, scapulars, and wing-coverts, bluish ash: quills the same; the first with the whole of the outer web black; first four primaries tipped with black, two or three of them with a small white spot at the extreme point; the fifth white at the extremity, with a black bar near the tip: rump and tail pure white: bill greenish yellow: inside of the mouth, and eye-lids, orange-red: irides brown: legs dusky brown, tinged with olivaceous. (Summer plumage). The whole head and neck pure white, without any bluish ash on the nape, or dusky streaks before the eyes: the rest as in winter. (Young of the year). Head, neck, and all the under parts, white, with the exception of a small spot at the anterior angle of the eye, a patch on the ear-coverts, and a larger crescent-shaped patch on the nape, which are dusky ash: back and wings deep bluish ash, the feathers tipped with dusky brown; the bend, and upper edge, of the wing, black; scapulars and secondary quills with large dusky spots; primaries black: tail black at the end, the extreme tips of the feathers whitish; the outer feather entirely white: bill, irides, and eye-lids, black. After the first moult, the back assumes the bluish ash, with still a few feathers intermixed spotted with brown; the spots on the head, and crescent-shaped patch on the nape, appear of a dark bluish ash; the wing-coverts also still spotted with dark brown; tail black at the extremity: bill greenish yellow spotted with dusky: forehead, and all the under parts, white. The plumage is not matured till after the second autumnal moult. (Egg). Stone-colour, thickly spotted with ash-gray and two shades of light brown: long. diam. two inches two lines and a half; trans, diam. one inch seven lines.
Not uncommon during the summer months on rocky coasts in the northern parts of the island. More rarely observed southwards. Breeds on the narrow ledges of steep cliffs, and lays three eggs. Food, small fish and marine insects. Obs. The Tarrock Gull of English authors is this species in its immature plumage.