Migration Routes of Some North American Birds
The Travelling Shore Birds.—Turnstones, Sanderlings, Curlews, and other denizens of the beaches and salt marshes migrate in great numbers along our Atlantic Coast. Some of them winter in the United States, and others pass on to the West Indies and southward. The extent of the annual journeys undertaken by some of these birds is indeed marvellous. Admiral Peary has told me that he found shore birds on the most northern land, where it slopes down into the Arctic Sea, less than five hundred miles from the North Pole; and these same birds pass the winter seven thousand miles south of their summer home. One of these wonderful migrants is the Golden Plover. In autumn the birds leave eastern North America at Nova Scotia, striking out boldly across the Atlantic Ocean, and they may not again sight land until they reach the West Indies or the northern coast of South America. Travelling, as they do, in a straight line, they ordinarily pass eastward of the Bermuda Islands. Upon reaching South America, after a flight of two thousand four hundred miles across the sea, they move on down to Argentina and northern Patagonia. In spring they return by an entirely different route. Passing up through western South America, and crossing the Gulf of Mexico, these marvellous travellers follow up the Mississippi Valley to their breeding grounds on the shores of the Arctic Ocean. Their main lines of spring and fall migration are separated by as much as two thousand miles. During the course of the year the Golden Plover takes a flight of sixteen thousand miles.
The World's Migrating Champion.—The bird which makes the longest flight, according to the late Wells W. Cooke, America's greatest authority on bird migration, is the Arctic Tern. Professor Cooke, to whom we owe so much of our knowledge of the subject, says of this bird:
"It deserves its title of 'arctic' for it nests as far North as land has been discovered; that is, as far North as the bird can find anything stable on which to construct its nest. Indeed, so arctic are the conditions under which it breeds that the first nest found by man in this region, only seven and one-half degrees from the pole, contained a downy chick surrounded by a wall of newly fallen snow that had been scooped out of the nest by the parent. When the young are full grown the entire family leaves the Arctic, and several months later they are found skirting the edge of the Antarctic continent.
"What their track is over that eleven thousand miles of intervening space no one knows. A few scattered individuals have been noted along the United States coast south to Long Island, but the great flocks of thousands and thousands of these Terns which range from pole to pole have never been noted by ornithologists competent to indicate their preferred route and their time schedule. The Arctic Terns arrive in the Far North about June fifteenth and leave about August twenty-fifth, thus staying fourteen weeks at the nesting site. They probably spend a few weeks longer in the winter than in the summer home, and this would leave them scarcely twenty weeks for the round trip of twenty-two thousand miles. Not less than one hundred and fifty miles in a straight line must be their daily task, and this is undoubtedly multiplied several times by their zigzag twistings and turnings in pursuit of food.
"The Arctic Tern has more hours of daylight and sunlight than any other animal on the globe. At the most northern nesting site the midnight sun has already appeared before the birds' arrival, and it never sets during their entire stay at the breeding grounds. During two months of their sojourn in the Antarctic the birds do not see a sunset, and for the rest of the time the sun dips only a little way below the horizon and broad daylight is continuous. The birds, therefore, have twenty-four hours of daylight for at least eight months in the year, and during the other four months have considerably more daylight than darkness."
Perils of Migration.—The periods of migration are fraught with numerous perils for the travelling hosts. Attracted and blinded by the torches of lighthouses, multitudes of birds are annually killed by striking against lighthouse towers in thick, foggy weather. The keeper of the Cape Hatteras light once showed me a chipped place in the lens which he said had been made by the bill of a great white Gannet which one thick night crashed through the outer protecting glass of the lighthouse lamp. As many as seven hundred birds in one month have killed themselves by flying against the Bartholdi Statue of Liberty in New York Harbour. As its torch is no longer lighted the death-rate here has been greatly reduced, although some birds are still killed by flying against the statue. Many were formerly killed by striking the Washington Monument, the record for one night being one hundred and fifty dead birds.
Locomotive engineers have stated that in foggy weather birds often hurl themselves against the headlight and frequently their bodies are later picked up from the engine platform beneath. Birds seem rarely to lose their sense of direction, and they pursue their way for hundreds of miles across the trackless ocean. Terns, Gulls, and Murres are known to go many miles in quest of food for their young and return through dense fogs with unerring directness to their nests.
