Let any man—if one there be—who is not profoundly impressed by the combined instinct and the reasoning of migratory birds do himself the favor to procure and study the 47-page pamphlet by Dr. Wells W. Cooke, of the U. S. Department of Agriculture, entitled "Bird Migration." I wish I could reproduce it entire; but since that is impossible, here are a few facts and figures from it.
The Bobolink summers in the northern United States and southern Canada, and winters in Paraguay, making 5000 miles of travel each way.
The Scarlet Tanager summers in the northeastern quarter of the United States and winters in Colombia, Equador and northern Peru, a limit to limit flight of 3,880 miles.
The Golden Plover (Charadrius dominicus).—"In fall it flies over the ocean from Nova Scotia to South America, 2,400 miles—the longest known flight of any bird. In spring it returns by way of the Mississippi Valley. Thus the migration routes form an enormous ellipse, with a minor axis of 2,000 miles and a major axis stretching 8,000 miles from arctic America to Argentina." (Cooke.) The Arctic Tern (Sterna paradisaea), is "the champion long-distance migrant of the world. It breeds as far north as it can find land on which to build its nest, and winters as far south as there is open water to furnish it food. The extreme summer and winter homes are 11,000 miles apart, or a yearly round trip of 22,000 miles." (Cooke.)
By what do migrating birds guide their courses high in air on a pitch-dark night,—their busy time for flying? Do they, too, know about the mariner's Southern Cross, and steer by it on starlit nights? Equally strange things have happened.
The regular semi-annual migrations of birds may fairly be regarded as the high-water mark of instinct so profound and far-reaching that it deserves to rank as high as reason. To me it is one of the most marvelous things in Nature's Book of Wonders. I never see a humming-bird poised over a floral tube of a trumpet creeper without pausing, in wonder that is perpetual, and asking the eternal question: "Frail and delicate feathered sprite, that any storm-gust might dash to earth and destroy, and that any enemy might crush, how do you make your long and perilous journeys unstarved and unkilled? Is it because you bear a charmed life? What is the unsolved mystery of your tiny existence in this rough and cruel world?"
We understand well enough the foundation principles of mammalian and avian life, and existence under adverse circumstances. The mammal is tied to his environment. He cannot go far from the circumpolar regions of his home. A bear chained to a stake is emblematic of the universal handicap on mammalian life. Survive or perish, the average land-going quadruped must stay put, and make the best of the home in which he is born. If he attempts to migrate fast and far, he is reasonably certain to get into grave danger, and lose his life.
The bird, however, is a free moral agent. If the purple grackle does not like the sunflower seeds in my garden, lo! he is up and away across the Sound to Oyster Bay, Long Island, where his luck may be better. Failing there, he gives himself a transfer to Wilmington, or Richmond, via his own Atlantic coast line.
The wonderful migratory instincts of birds have been developed and intensified through countless generations by the imperative need for instinctive guidance, and the comparatively small temptation to inductive reasoning based on known facts. Evidently the bird is emboldened to migrate by the comfortable belief that somewhere the world contains food and warmth to its liking, and that if it flies fast enough and far enough it will find it.
As a weather prophet, the prescience of the bird is strictly limited. The warm spells of late February deceive the birds just as they do the flowers of the peach tree and the apple. Often the bluebirds and robins migrate northward too early, encounter blizzards, and perish in large numbers from snow, sleet, cold and hunger.