Page:Popular Science Monthly Volume 60.djvu/340

332 route in a southeasterly direction. When examples from Great Britain were introduced into New England, they adapted themselves readily to their new surroundings and reared young, but when the season for migration arrived the inherited tendency to go in a southeasterly direction asserted itself, and, according to Mr. Wm. Palmer, of the U. S. National Museum, they all passed out into the broad expanse of the Atlantic and were lost.

For several decades it has been noted that a few species of birds from Western Asia have been gradually extending their summer range into northern Scandinavia. When these species migrate, instead of going south through central Scandinavia or southwest along the coast line, as do the original Scandinavian residents, they turn back east to the point in Siberia whence they came, before turning southward to spend the winter on the borders of India.

Forty or more species of migratory birds occur as summer residents in the Yukon Basin, Alaska. Of these some fourteen species are Pacific coast birds. With a single exception they are all thought to reach the upper Yukon by crossing the Alaskan coast range of mountains. This exception, according to Mr. W. H. Osgood, of the U. S. Department of Agriculture, is the varied thrush (Hesperocichla nœvia), which apparently reaches its summer home by going up the coast to the mouth of the Yukon, and thence following this river for almost 2,000 miles. Equally abundant with it in this summer home is the common snowbird (Junco hyemalis) of the eastern United States, which reaches the Yukon Basin by way of the Mississippi Valley.

Perhaps the longest straight-away flight made during the migrations is accomplished by certain shore and water birds, as the tattler (Heteractitis incanus), sanderling (Calidris arenaria), turnstone (Arenaria interpres), and the pintail and shoveler ducks, which nest in islands in the Bering Sea and spend the winter in the Fanning and Hawaiian groups, a distance of some 2,200 miles. As the shore birds above enumerated are probably unable to rest on the surface of the water, the entire distance must be accomplished in a single flight. It is difficult indeed to see how this line of migration could have been established. Following the analogy of the Old World species before mentioned whose path marks an ancient shore-line, we might presume that there was at one time a land connection, or at least a chain of islands between the Aleutian and Hawaiian groups, but on the contrary the depths of the Pacific are profound between these points, and there is not the slightest geological evidence on which to base a former land connection. When it is recalled how slight a deviation at the point of departure would suffice to throw them to the one side or the other of the Hawaiian islands the accomplishment is truly marvelous. In the absence of familiar landmarks and surrounded by a waste of