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THE DAY FLYERS
SOME birds travel only by day; others, only by night; while a smaller number travel both by day and night.
The day flyers are strong of wing. Many of them live in the open, in the fields or marshes and along the beaches. Or if their home is in the trees, they do not hesitate to leave them, and often make long flights in their search for food. ‘All the birds which gather nightly in roosts, like Robins, Grackles, Swallows, Swifts, and Crows, are day flyers. Blue Jays, Waxwings, Bluebirds, many of the Finches, like Crossbills, Redpolls, and Snowbuntings, and even the tiny Humming-birds travel by day. “But,” you may well ask, “why should not all birds travel when they have light to see the way, and sleep at night as they do when they are not migrating?”
The answer is that only those birds venture forth by day which can fly fast enough to escape from bird-killing Hawks. Not all Hawks prey on birds. Most of them live chiefly on mice. But Cooper’s Hawk, the Sharp-shinned Hawk, and the Duck Hawk are all cannibals. Woe to the bird they chase, unless it is swift enough to outdistance them or escape to the nearest cover!
Ducks and Geese, most Snipe and Plover, and sea birds like Gulls and Petrels, travel both by day and night. They are among the birds which carry fuel for the engine and can go long journeys without stopping for a fresh supply.
Have you ever seen birds migrating by day? Sometimes it is difficult to tell whether passing birds are simply flying to or from the roost or whether they are actually embarked on their great journey. When, on some late summer or early fall afternoon, we see Swallows hurrying southward, we might well imagine that they were bound for their winter homes instead of their beds in the marshes. But when we hear the clarion honking of Wild Geese, and, looking upward, see the flying wedge cleaving its way steadily and rapidly through the sky, then we know that we are seeing real bird travelers and we wonder where they have come from, where they are going, and how they can possibly find the way.
Then in the early spring, when the black flocks of chattering Red-wings and Grackles come and fly onward toward the north we know that they belong to the army which soon will take possession of the land.
Robins usually migrate in scattered companies, or “loose flocks” as they are termed. Bluebirds have much the same habit but are perhaps even more scattered. When they are traveling one can hear their soft flight-note, túrwee, túrwee, all day long as bird after bird passes overhead.
Crows migrate much as they return to the roost. In March and October one may see single birds or groups of three or four flying rather high and as though they had an important engagement somewhere. Such flights may last all day, while the return-to-the-roost flight, we know, takes place only in the late afternoon.
Hawks also travel in this way. Some days in the fall one or more Hawks will be in sight from morning until evening, all flying in the same direction as though they were going to the same place.
In the spring, on the eastern slope of the mountains of Vera Cruz, Mexico, I have seen flocks containing thousands of Hawks migrating northward. Although closely massed they did not move onward in a solid body like a flock of Blackbirds, but, like a swarm of bees, circled about and among each other in a most remarkable and confusing manner. However, in spite of their wheeling they all passed rapidly northward and were soon out of sight.
Some years later, in March, in the same part of Mexico, I saw a flock of several thousand White Pelicans migrating northward. These great birds measure eight feet from tip to tip of their outstretched wings. Like the Hawks, their flight was not in a direct line, but in a series of intertwining loops. The sun shone on their snowy plumage, and against the background of blue mountains they made a sight of great beauty. They were as dazzling white as snowflakes in a squall, but unlike snowflakes their motions were as stately and dignified as those of dancers in a minuet. So, sweeping gracefully around each other, they, too, were quickly lost to view.
Why birds should
travel in this manner instead of “as the Crow flies,” I cannot say. It must at
least double the distance they cover. We cannot believe they keep rounding up
the flock to prevent any stragglers from being lost, for we have found in what
scattered companies Hawks, perhaps of the same kind as those seen in Mexico,
travel in the fall. Possibly these spring flights may have something to do with
the courtship customs of that time of year.
A PATHWAY IN THE AIR
It is most interesting to observe how closely widely separated flocks or groups of migrating birds follow the same invisible pathway through the air. I have seen Swallows flying northward in small bodies which followed each other at short intervals. The last ones to pass would be far out of sight before the next birds arrived, for they were flying not more than twenty feet above the earth; but each Swallow followed those that had gone before it as though guided by the marks of wing beats in the air.
In the same way I have seen Herring Gulls in the spring migrating over my home at Englewood, New Jersey. They were flying toward the northeast in flocks of fifteen to twenty birds and were about one thousand feet above the earth. At times several flocks could be seen at one time. Then several minutes would pass without any more Gulls appearing. But soon another flock would come out of the southwest and follow as directly after those which were now several miles ahead, as though there were guideposts in the sky.
Besides those day travelers which fly near enough to the earth to be seen, there are others which fly too far above us to be within range of our eyes. On September 30, 1894, an astronomer at Shere, England, was studying the sun through a telescope. Every few seconds, during the ten minutes he watched, a bird was seen to pass slowly across his field. All were flying in a southerly direction; but with the naked eye not a bird could be seen.
Our ears really tell us more than our unaided eyes about the day flyers which are traveling far up in the sky. With nothing to turn them from their course, sound waves carry surprising distances either up from the earth or down to it.
Balloonists tell us how clearly they can hear voices of people who are almost indistinguishable. So we may hear the notes of passing birds which are traveling at too great a height to be seen. The mellow whistles of certain Snipe and Plover tell us that they are passing on the birds’ air line when it is impossible for us to see them. But if we answer we may in time see a black speck in the sky, which responds to our call and finally circles close overhead.
On one occasion in
Central Park, New York City, I heard the flute-like call of a Yellow-leg Snipe
which was migrating high over the city Perhaps he was calling to some companion
in the sky. Certainly there was nothing on the earth to attract him. But
putting my fingers to my lips I whistled a loud imitation of his notes. Quickly
he answered. I whistled again, and soon could see a black dot circling high
above me. Larger and larger it grew, louder and more frequent became his cry,
and within a minute, much to the surprise of the passers-by, the bird was
flying anxiously back and forth just over my head. But unable to find the
“bird” which had called to him, he soon mounted high in the air and continued
THE PASSENGER PIGEON
One of the most remarkable of day flyers was the Passenger Pigeon. At times several days were required for the migrating hosts to pass a given point. The procession stretched from horizon to horizon and was a mile or more in width. Often the sun would be obscured by the clouds of flying birds.
In 1808, Alexander Wilson, America’s pioneer ornithologist, estimated that during a great flight of Pigeons which he saw in Kentucky, 2,230,272,000 birds passed in four hours. Twenty years later they were still so abundant that Audubon wrote: “I have satisfied myself by long observation that nothing but the gradual diminution of our forests can accomplish their decrease.” But Audubon did not realize the power of the market gunner unrestrained by law. Forests we still have, but of the Pigeons not one remains.
SUGGESTIONS FOR STUDY
Mention some of the commoner day flyers. Have you ever seen any of them migrating? How far above the earth were they? Were they flying in flocks or singly? Which way were they going? Compare the habits of day flyers with those of night flyers. How do Crows migrate? Have you ever heard birds calling when they were at too great a height to be seen? Is it probable that birds migrate during the day at so great a height as to be out of sight? Do traveling birds answer the calls of others of their kind? What are the differences between a Mourning Dove and a Wild Pigeon? In what part of the country were Wild Pigeons once found; how many did Wilson estimate passed him in four hours? Did these birds nest in scattered pairs like Doves, or in colonies? How large an area is said to have been covered by a single nesting community of Wild Pigeons? How many nests have been seen in a single tree? What causes led to the extermination of the Passenger Pigeons? When was the last one seen alive in nature?