The Whimbrel only passes through these islands on migration, though a few pairs breed on the Orkneys and Shetlands. The spring passage generally takes place in May, from which it is known in some countries as the May-bird. In habits and food it closely resembles the Curlew, but its note is very different, being a rather melodious rippling whistle, which may be syllabled as “telly, telly, telly, tet.” The fells of Arctic Europe form its chief nesting-grounds, whence it migrates in winter to the shores of the Mediterranean. In plumage it is very similar to the Curlew, but may always be distinguished by having the crown of a uniform dark brown with a pale stripe down the centre. It is also a much smaller species. Length 17·5 in.; bill 3·4 in.; wing 10 in. [Illustration: CURLEW _Numenius arquata_] THE ESKIMO CURLEW Numenius borealis (J. F. Forster) The home of this bird is in Arctic America, and some eight or nine examples have been procured in this country. In appearance it is rather like a small Whimbrel, but it may be recognised by the absence of barring on the primaries, no white on the rump, transverse arrow-head markings on the under parts, and the axillaries being chestnut barred with brown. Length 14 in.; wing 8·25 in. THE BLACK TERN Hydrochelidon nigra (Linnæus) Up till the middle of last century the Black Tern was a regular summer visitor to our shores, remaining to breed in the fens and marshes of England. For the last forty years, however, it has only occurred on passage, the adult birds passing through in April and May, and flocks in immature plumage being found along the east coast in the autumn. To the west of England and Scotland it is a very irregular visitor, and the same may be said of Ireland. It nests in colonies on inland marshes, the nest being an accumulation of decaying vegetation floating on the surface of the water. The eggs, three in number, are olive green blotched with dark brown. Its food consists largely of aquatic insects and their larvæ, dragon-flies and such like, but it also feeds readily on small fish. South of the Baltic it breeds in suitable localities throughout Europe, migrating from its more northerly summer quarters to Africa. The adult in summer has the head, neck, and under parts dark greyish black, the rest of the plumage slate grey, except the vent and under tail coverts, which are white. Bill black. In winter the forehead, nape, chin, throat, and under parts are white. The young resemble the adults in winter, but the upper tail coverts are lighter and the back and wing coverts are greyish mottled with brown. Length 10 in.; wing 8·5 in. THE WHITE-WINGED BLACK TERN Hydrochelidon leucoptera (Schinz)