Page:The Migration of Birds - Thomas A Coward - 1912.pdf/75

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ORIENTATION AND ROUTE FINDING
59

Knock Lightship, Mr Eagle Clarke noticed that birds flew so low along the water that they could not possibly have seen their way.

It is purely speculative to say that the young bird which travels alone, for it seems certain that many young do travel unguided on their first journey, has an inherited memory of the actual route to be followed, but that it has an hereditary sense of direction, or an hereditary impulse to travel in a certain direction, is quite another matter. The sea, to the young bird, may be a barrier; it may wander coastwise and be lost, or, if this is the best way, find itself at the desired haven If the shortest and quickest way is across the ocean, the young bird may brave the perils and succeed, or on this trackless waste it may wander till it sinks to the waves and be added to the long list of failures.

Certain species summer in Greenland either in the same areas or in areas comparatively near to one, another; some of these travel in autumn south-east, and winter in Europe or Africa, and others go south-west into the States or South America. Most of these are distinctly eastern or western forms, but occasionally American birds are met with in Europe, and European in America. Probably at the start these stragglers joined the wrong band, and travelled for company and unconsciously by the wrong route. Birds drifted to leeward may