Birds and Birding's Guide to:

Watching THE MIGRATIONS OF BIRDS

Migration Routes of Birds

The persistence with which birds cling to established lines of travel during the migrations is one of the most remarkable facts within the range of bird life, and this in not a few cases can only be interpreted in the light of past geological conditions.

Thus certain species which breed in Europe and spend the winter in Africa now cross the Mediterranean at one of the widest points, a seemingly needless waste of energy. But soundings between these points have shown that the sea for much of the distance is relatively shallow, and that a moderate subsidence has changed what may have been narrowest to what is now one of the broadest points.

This subsidence was undoubtedly slow and first resulted in the formation of a series of islands and lagoons, and the birds easily passed from one island to another, and even after the last bit of land had disappeared they still followed the old route established by their remote ancestors.

Many shore and water birds that spend the breeding season in and about the Arctic Circle to the north of Europe and Asia, follow lines of travel during their migrations that were undoubtedly established under past continental or oceanic conditions.

Thus certain species take a circuitous route over what is now a wide expanse of open ocean, while others pass far inland through the Russian and central European lowlands. Those of the first class are simply still following an ancient shore-line, and those of the second class the location of an inland shallow sea. In other cases there is little evidence of former land connection, for many North American species, even of the smaller land birds, cross the Gulf of Mexico at its widest part.

The Old World Migratory Quail (Cotumix coturnix) is one of the comparatively few migrants among the so-called game birds. During the migrations they wander far from places of their birth, reaching South Africa, Persia, and India.

The individuals inhabiting Great Britain, or at least a part of them, long ago established a migration 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. William Palmer, of the U. S. National Museum, they all passed out into the broad expanse of the Atlantic and were lost.

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