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V THE BIRDS’
TIME-TABLE WHEN we consider the great distances some birds travel and the dangers they encounter by the way, it is remarkable that they usually arrive on time. That the daily
trips to and from the roost should be made regularly is not surprising. The
birds have only a short way to go, and they leave soon after daybreak and
return just before dark. But when, year after year, the Bobolink, the Baltimore
Oriole, the midget Humming-bird, many Warblers and other birds arrive from
journeys thousands of miles in length on exactly or nearly the same day, we ask
how they can possibly be so prompt. In order to answer
this question we must know something about the birds’ time-table. Anyone who
has studied the birds about his home for many years can make a time-table
giving the dates of the arrival and departure of all the migratory birds which
visit him. In this time-table
we will notice that the early birds—those which come in March—are much less
prompt than the later ones—those which come in May. This is because the weather
of March is so much more uncertain than that of May. In some years, near New
York City, snow covers the ground and the ponds are frozen almost until April.
In others, the snow melts and the ice disappears before the middle of March.
But by May 1, the weather is more settled. The first week in May of one year is
much like the first week in May of another year. So it follows that
the exact time of the arrival of the birds is more or less dependent on the
weather. But it is not the weather which induces them to start. What can the
Baltimore Oriole in Central America know about the weather near New York City?
Not a thing. Fie leaves Central America without regard to the weather there or
any other place. But his journey may be delayed by bad weather or hastened by
favorable weather. If, therefore, he finds the weather of one year much the
same as that of another year, he is apt to reach the same place at about the
same time year after year. Sometimes, encouraged by an unusually mild period,
birds come so far ahead of their usual time that they are trapped by the sudden
return of cold weather. Then, if they do not retreat, they may suffer for
lack of food. I have seen Geese on the coast of Texas migrating northward in
large numbers, urged onward by a warm wave. The next day, to my
surprise, they all came flying back. But the day following a severe “norther”
suddenly arrived. The Geese had evidently encountered this storm and been
driven back by it. Observations of this kind lead us to believe that birds are
not such good weather prophets as they are commonly supposed to be. The first birds to
come in the spring are, generally speaking, the last ones to leave in the fall.
In early March we look for Robins, Grackles, and Red-winged Blackbirds, and
there will be additions to the ranks of the Song Sparrows and Bluebirds that
have passed the winter. These same birds will remain until November or even
early December. When the frost
leaves the ground so that the Woodcock may probe for his favorite fare of
earthworms, this great-eyed Snipe of the woods will appear; and he may stay
with us until frost seals his hunting ground. Almost as soon as
the ponds, lakes, and rivers open, Ducks and Geese return, and, in the fall,
many remain until they are actually “frozen out” by the ice which forces them
to go further south. Now none of the
birds I have mentioned makes very long journeys. Robins, Grackles, Redwings
and Woodcocks do not leave the United States, and the greater number of Ducks
winter within our boundaries. In fact, all these birds may be found as far
north as Virginia. Therefore, they are in the first rank of the vast army of
birds which begins its northward march in the early spring. They may not start
any sooner than the Bobolink in southern Brazil, but they have a much shorter
journey to make and so get here first. THE BIRDS’
PROCESSION What a marvelous army it is! Four or five thousand miles separate the advance guard and rear guard. Between them are untold myriads of migrant Flycatchers, Warblers, Vireos, Thrushes, and other birds. Some are already under way, some are waiting the call to “fall in,” but all in their proper season will take up the march and at their due date reach their destination.
Let us take a
position, say near New York City, and watch this vast army pass. If we were in
Washington we should see it about a week earlier; while in Boston it would be a
week later. It is a joyous day
when, early in March, we first hear the martial music of the Grackles and
Red-wings, and the cheery salute of the Song Sparrow. Not a bud has broken, not
a blade of grass grown. The birds bring us the earliest news that spring is
near. Soon we shall hear the fifing of the Meadowlark and the musical whistle of the Fox Sparrow; while those who know its haunts may hear the strange twilight song and see the sky dance of the Woodcock. Late in the month,
when in some warm place gnats are floating in the sunlight, the Phoebe,
earliest of Flycatchers, will be there to devour them. In early April the chant
of the Field Sparrow, the bright, ringing notes of the Vesper Sparrow, and the
gurgling, glassy call of the Cowbird will be added to the music of the
feathered band. With them will be Chipping and White-throated Sparrows, Myrtle
Warblers, Tree Swallows and Hermit Thrushes. Thus far the army has advanced rank after rank in orderly array. All the birds in it have come from their winter quarters in the southern United States, but about April 15, the Barn Swallow appears. He is the first bird to reach us from tropical America. Like an aerial scout he dashes ahead of the slower columns. A little later he is joined by the Cliff and Bank Swallows. Then, if we are so fortunate as to have Purple Martins as tenants, we may expect to hear them chattering happily about the houses we have offered them as homes.
Some morning about
April 25, when we open our windows to the warm sun rays, the House Wren will
greet us with his merry little trill. He is bobbing in and out of a bird
house—perhaps the very one he nested in last year. A Catbird sings
from the heart of a lilac bush, while from the topmost branch of some tall tree
the Brown Thrasher, in loud, ringing notes, tells us that he is home again. That evening we may
hear the twittering of Chimney Swifts just back from Central America, and see
their bow-and-arrow-like forms sailing overhead. The army now is moving
rapidly and with closed ranks. Company after company hurries by; others stop to
camp with us. It is an exciting time for us on the lookout. Sharp indeed are
the eyes and keen the ears that see and hear all that is to be seen and heard.
Between May 7 and 12, when the migration is at its height, as many as one
hundred and forty different kinds of birds have been seen by one person on one
day. This was at Oberlin, Ohio, a place through which many birds pass. For we
have seen that there are certain lines of flight, or highways, which are
followed by birds in their travels. On the Atlantic coast it is rare to see
more than one hundred different kinds of birds in a single day during
migration. The first days of
May will bring the Rose-breasted Grosbeak, Baltimore Oriole, and Scarlet
Tanager, all famous colorbearers. Then we may look for the great Warbler
cohorts. These active little wood-sprites are the most beautiful and the most
numerous of any of the members of the great feathered army. Over thirty different
kinds and an incalculable number of individuals will march by us. How few
people know that every year we are visited by these gems of bird life! Although
among the smallest members of the army, as a family they make the longest
journeys. The greater number
spend the winter in the Tropics and the summer in northern New England and
Canada. But in spite of their size and the great distance they travel they
closely follow the time-table. Generally it will tell us within a day or two
when to expect them. The Warblers form
the rear guard of the army. After May 20, few migrants will arrive, and in
early June only stragglers will be seen. From the beginning,
if we have watched closely, we have noticed several things. First, we have
found that the male birds come before the female. Remember that all the
Red-wings in the early March flocks had red shoulder marks; that the Grackles
were all large and glossy; that the Cowbirds had brownish heads and shining
bodies. When the male and female are alike in color and cannot therefore be
distinguished, remember how often our attention has been drawn to a newly
arrived bird by its song. Since the female rarely sings, we may safely say that
any bird we hear singing is a male; and thus, even when he is colored like his mate,
we know that the male is the first to come. With the earlier
birds the female does not come until a week or ten days after the male. The
male Red-wing, for example, returns to the marsh in which he and his mate lived
the year before and calls his kong-quer-ree
many times before she hears him and comes to choose a nesting place. Then we will also
see that while many birds march on to more northern homes others break ranks
and make their homes with us. These the ornithologist calls “Summer Residents,”
while those that pass onward he calls “Transient Visitants.” By June 1, the
invading hosts have taken possession of the country. Some have settled in the
north; but from the Gulf of Mexico to the shores of the Arctic Ocean, no place
is without some members of the great army. Where, in the
winter, all was silent, we now hear the sweet voices of many birds. How
peaceful they seem as they build their nests and rear their young! But in truth
they are valiant fighters; for this bird army has come to protect us from our
insect enemies. All summer long they will carry on constant warfare against the
caterpillars, cut-worms, weevils, and other harmful insects, which, if they
were not preyed on by birds, would destroy our crops. RETURNING TO THE
WINTER HOME No sooner has the
invasion ended than preparations for the retreat to winter quarters begin. We
have already seen that in early June the Grackles and Robins drill their
families for the great journey by daily trips to and from the roosting places.
In July the young Swallows are given their lessons; and late in that month the
Bobolink actually begins his southern migration. By August 20, the retreat is
well under way and from that time until September 30, our woods are again
thronged with traveling Warblers, Vireos, Flycatchers, and other birds. Most
of them have changed the bright uniform of spring for a duller coat in which we
may find it difficult to recognize them. In October they
will be followed by the Juncos and Tree Sparrows; and in November, if food is
scarce at the north, we may hope to see Crossbills, Redpolls, and even Pine
Grosbeaks. All these late arrivals will stay with us until spring. By the
ornithologist they are classed as “Winter Visitants.” Birds like the
Golden Plover and Turnstone, that have to cross two thousand or more miles of
ocean and are not believed to alight upon the water, cannot, of course, rest by
the way. But the Warblers and other small birds that migrate chiefly over land
evidently rest for several days after making an all-night flight. During this
time they may travel a little by day, as they hunt insects from tree to tree,
or if they have happened to come down into some small piece of woodland such as
is found in city parks, they may remain in the same place until they are ready
to continue their journey. While they are
waiting they may be passed by other birds of their own kind, and while these
birds are resting somewhere On ahead they may in turn fly on ahead of them. An
individual bird may therefore fly four or five hundred miles in one flight, but
because of these rests between flights the species to which it belongs does not
make anything like this rate of speed. Professor Cooke’s
studies for the Biological Survey at Washington have told us more about the
speed at which the bird army advances than we knew before. Thus he has found
that for the first month of their northward journey, Robins make an average
advance of only thirteen miles a day. The next ten days they go forward at
double this pace. Then, as the season becomes rapidly warmer, the rate rises
to fifty, and soon to seventy miles a day. This increase in speed does not mean
that the Robin flies faster but that its rests are shorter. The same authority
tells us that when traveling from the Gulf of Mexico to Minnesota, Blackpoll
Warblers average only thirty to thirty-five miles a day, but before they reach
Alaska they have raised this rate to two hundred miles a day. So while the
journey of one thousand miles from the Gulf of Mexico to Minnesota takes thirty
days, the two thousand five hundred miles from Minnesota to Alaska is made in
half that time. Like flowers and
trees, birds are closely dependent on the weather. How little change there is
for weeks after the first skunk cabbage is seen, or the first pussy-willow
blooms! Then, as the days grow warmer, the woods are suddenly filled with
flowers and the trees thickly covered with leaves; and with these come the
birds. From this glance at
the birds’ time-table, we have learned that nearly every month in the year has
its bird travelers. This is one of the reasons why the study of birds is so
interesting. There is always something happening in the birds’ world. Someone
is coming or someone is going. We are continually greeting old friends or making
new ones. Will it not add
greatly to our pleasure to know where they have been and whither they are
bound? SUGGESTIONS FOR
STUDY What is the first
bird traveler you see in the spring? When does it generally arrive? Where do
you think it has passed the winter? At about what date does the Robin arrive?
Does it come alone or with others? When does it become common? Do the first
arrivals sing? Why should birds arrive with more regularity in May than in
March? How does weather affect the migration of birds? Are birds good weather
prophets? Where do most of the first arrivals come from? Where have many of the
last arrivals spent the winter? Trace on the map the region occupied by the
army of marching birds when the first ranks are passing the latitude of New
York City. Mention some of the bird travelers of March; of April; of May. When
do the Warblers come? When is the spring migration finished? What name is
applied to those migrants which pass us to nest further north? To those which
remain to nest with us? When does the fall migration begin? When is it
concluded? |