In summer the adult has the whole of the upper parts, including the tail, pearl grey; head and nape dense velvety black; primaries blackish. Under parts pure white; bill and legs black. In winter the head is white streaked with black. Length 15·5 in.; wing 13 in.
THE CASPIAN TERN
Sterna caspia, Pallas
This large Tern is, like the preceding, only a rare straggler to our shores. It nests in Denmark and various islands on the Baltic, as well as in the Mediterranean basin eastwards to the Aralo-Caspian area.
Plumage much as in preceding species, but the tail nearly white. Bill vermilion red; legs black. Length 20 in.; wing 16 in.
THE SANDWICH TERN
Sterna cantiaca, J. F. Gmelin
This species arrives on our coasts about the middle of April and at once repairs to its breeding-stations. In England these are very few in number and mostly in the north, but occurring equally on the east and west coasts. In Scotland the colonies are rather more numerous, while Ireland can only boast of one in the north.
It nests on the bare shingle, the nests being usually placed quite close to each other. Two or three eggs of a pale stone colour, spotted and blotched with reddish brown and black, form the clutch.
Like all Terns, this bird is a powerful flier, and seizes the fish on which it feeds by plunging into the water with considerable force. Its note is a loud and harsh “kirhitt,” which may be heard some way off and often enables this species to be detected when among other Terns. It leaves our shores as soon as the young are well on the wing, and though a few stragglers may occur on the coast during the autumn it is by no means a common species, and needs all the protection it can get, if it is to remain an annual summer visitor to our shores.
The adult male in summer has the crown of the head black; the rest of the upper parts pearl grey; rump, tail, and under parts white, the breast being suffused with a delicate rose tint which soon fades after death. Bill black with a yellow tip. Legs black. The female is similar but slightly smaller. In autumn the back of the head and nape are white, the latter being lightly mottled. In the young the head is white mottled with black. The feathers of the back and wing coverts have black and brownish crescentic markings and white tips. The tail is also marked with angular lines of black, the outer feather being almost entirely greyish. Length 16 in.; bill 2·5 in.; wing 12 in.