Page:The Migration of Birds - Thomas A Coward - 1912.pdf/85

Rh reached the north coast of South America. The New Brunswick birds cannot be ready to leave before the middle of July, and Mr Cooke allows them fifty days for the trip, bringing them to the Gulf States in September; he argues that this is proof that the earlier migrants must have been birds from the southern part of the range. Black-throated blue warblers, Dendroica coerulesens, reach Cuba at about the time that others of the same species are arriving in North Carolina; the first, he concludes, are birds from the southern Alleghanies and the others from northern New England or beyond (20). Other species illustrate the same order which he calls "normal," but show that it is not an invariable rule.

Southern-bred Maryland yellow-throats, Geothlypis trichas, reside throughout the year in Florida; those in the middle districts of the range migrate for a short distance only, whilst the Newfoundland birds pass over the winter home of their southern relatives to the West Indies. The palm-warblers of the interior of Canada travel 3000 miles to Cuba, passing through the Gulf States early in October; those from north-eastern Canada travel later and slowly and settle in the Gulf States, after a journey of only half the distance. He sums up wisely—"No invariable rule, law, or custom exists in regard to the direction or distance of migration.