Page:The Migration of Birds - Thomas A Coward - 1912.pdf/84

68 larger bird appears, the Greenland wheatear, Saxicola oenanthe leucorhoa, which was recognised in Greenland, Iceland and eastern North America before it was seen that both forms occurred in Britain. This larger bird loiters through Britain, for its northern home is not ready for it until the Arctic spring. We know it breeds farther north than our wheatear, but its winter range is not fully worked out. The smaller bird is found in north and north-western Africa, and the larger form farther east, even south of the equator on the eastern seaboard, and probably, when we know more about the range of the two we shall find that the form breeding farther north, winters farther south.

The folly of laying down the law on the strength of the knowledge of the habits of a few species is shown by the study of the movements of American birds. Mr Cooke shows that as a rule "the migration is a synchronous southward movement of the whole species" in autumn, "the different groups of individuals or colonies retaining in general their relative position." The black and white creeper Mnistritta varia breeds from South Carolina to New Brunswick, nesting in the south in April and reaching the northern limits in the middle of May. In the middle of July old and young birds have been seen at Key West, 500 miles south of the breeding range, and towards the end of August they have