The Gra.s.shopper Problem. Bulletin 84.

The Boll-Weevil Problem. Bulletin 344.

The Most Important Step in the Control of the Boll-Weevil. Bulletin 95.

The San Jose Scale. Yearbook 1902.

The Plum-Curculio. Bulletin 73.

The Apple Codling-Moth. Bulletin 41. Price 20c.

The Gipsy Moth and How to Control It. Bulletin 275.

The Brown-tail Moth and How to Control It. Bulletin 264.

The Spring Grain Aphis or Green-Bug. Bulletin 93.

The Army-Worm. Bulletin 4.

The Hessian Fly. Bulletin 70.

The Chinch-Bug. Bulletin 17.

The Princ.i.p.al Household Insects of the U. S. Bulletin 4.

Insects Affecting Domestic Animals. Bulletin 5.

CHAPTER XI

BIRDS

Birds give us pleasure in three ways: by their beauty, by their song and by their usefulness in destroying animals, insects or plants which are harmful to man.

But although they are among man's best friends they have been greatly misunderstood, so that to the many natural enemies that are constantly preying on birds, we must add the warfare that man himself wages on them, and the cutting down of their forest homes. This work of bird destruction has gone on until all the best species are greatly reduced in numbers and some species have been almost entirely driven out.

To see how serious a matter this is we must study the food habits of birds, and we shall find that although the different species eat a large variety of food, in almost every case their natural food is something harmful to man.

The large American birds, the eagles, hawks, owls and similar kinds, are called birds of prey because they feed on small birds and animals. Some of these are of the greatest benefit to the farmer, while others are altogether harmful. Another large cla.s.s of birds lives almost entirely on injurious insects and this cla.s.s is ent.i.tled to the fullest care and protection from the farmer.

Still another cla.s.s lives largely on fruits, wild or cultivated, and on seeds, which may be either the farmer's most valuable grains, or seeds of the weeds that would choke out the grain.

It can not be denied that birds often do serious damage through their food habits; but the great mistake that has been made in man's treatment of birds has been in hastily deciding that if birds are seen flitting about fields of grain they are destroying the crop. A better knowledge of their food habits will lead to proper measures for destroying the harmful kinds and protecting the useful ones.

Successful agriculture could hardly be practised without birds, and the benefit to man, though amounting each year to millions of dollars, can hardly be estimated in dollars and cents, since it affects so closely the size of our crops, the amount of timber saved for use in manufactures, and even the health of the people.

Here again we see the careful balancing that runs through nature; how carefully each thing is adjusted to its work. Naturally the balance between birds, insects and plants would remain true, no one increasing beyond its proper amount. But when man begins to destroy certain things, and to cultivate others, this balance is seriously disturbed. The birds that destroy weed seeds being killed, weeds flourish in such vast numbers as to drive out the cultivated crops. The birds which destroy mice, moles, gophers, etc., being killed, these animals become a nuisance and cause serious losses. If insect-destroying birds are driven out, the farmer will be at the mercy of the insects unless he employs troublesome and expensive methods of getting rid of them. Certain favorable conditions cause large numbers of birds to gather in a small region and they become a pest. Very careful observation has shown that in nearly every case the favorite food of the birds is something which is not valued by man, and if this food is provided, the farm grains and fruits will not be seriously molested.

Few birds are altogether good, still fewer are altogether bad; most species are of great benefit, even if at the same time they do some harm. Some birds do serious damage at one season, and much good at another. The most notable example of this is the bobolink, which in northern wheat fields is loved no less for his merry song than for the thousands of weed seeds and insects he destroys; while in the South he is known as the reed-bird or rice-bird, the most dreaded of all foes to the rice crop.

Flying down on the fields by hundreds of thousands these birds often take almost the entire crop of a district. The yearly loss to rice-growers from bobolinks has been estimated at two million dollars.

If crows or blackbirds are seen in large numbers about fields of grain they are generally accused of robbing the farmer, but more often they are busily engaged in hunting the insects that without their help would soon have destroyed his crop; and even if they do considerable damage at one season they often pay for it many times over.

Whether a bird is helpful or the reverse, in fact, depends entirely on the food it eats and often even farmers who have been familiar with birds all their lives do not know what food a bird really eats. As an example of the misunderstanding that is often found in regard to birds, when hawks are seen searching the fields and meadows, or owls flying about the orchards in the evening, the farmer always supposes that his poultry is in danger, when in reality the birds are quite as likely to be hunting for the animals which destroy grain, produce, young trees, and eggs of birds.

In order to correct such mistaken ideas the Department of Agriculture has made a most careful and accurate study of the habits of birds, and it is the results of these observations that are recorded here.

Field workers from this Department who have observed the habits of the princ.i.p.al birds that live among men, have watched them all day and from one day to another as they fed their little ones, and, to be more certain of their facts, they have examined the stomachs of hundreds of birds, both old and young, to learn exactly what each bird had eaten. In this way they have proved absolutely that many species that are supposed to eat chickens, or fruit or grain, in reality never touch them, but are among the farmer's best friends.

Among other things they have learned that while they are feeding their young, birds are especially valuable on a farm. Baby birds require food with a large amount of nourishment in it that can be easily digested.

Almost all young birds have soft, tender stomachs, and must be fed on insects; as they grow older, the stomach or gizzard hardens and is capable of grinding hard grain or seeds. The amount of food required by the baby birds is astonishing. At certain stages of their growth they require more than their own weight in insects. And the young birds are to be fed just at the season that insects do the most injury to growing crops of grain and young fruit and vegetables.

Birds vary so much in the kind of food eaten, not only by different varieties of the same species, but by the same birds at different seasons, that it is necessary to make a careful study of each bird to know whether, if he is sometimes caught eating cultivated fruit and grains, he helps in other ways enough to pay for it.

When insects are unusually abundant, birds eat more than at other times and confine themselves more strictly to an insect diet, so that at such times the good they do is particularly valuable.

Birds of prey may do harm in a particular place, because in that region mice, rabbits and other natural food are scarce, and they are driven to feed on things that are useful to man, while in places where their natural food is plentiful the same birds are altogether helpful.

In the same way, birds which naturally eat weed seeds frequently find these almost altogether lacking where the farms are most carefully cultivated, but in their place are fields of grain whose seed also furnishes them desirable food. Is it any wonder, then, that, their natural food being taken from them, they turn to the cultivated crops?

The fruit eating birds seem always to choose the wild fruits, but where these are not to be had they enter the orchards and soon become known as enemies of the farmer.

A careful examination of the harm done by birds leads to the belief that the damage is usually caused by a very large number of one species of birds living in a small area. In such cases so great is the demand for food of a particular kind that the supply is soon exhausted, and the birds turn to the products of the field or orchard. The best conditions exist when there are many varieties of birds in a region, but no one variety in great numbers, for then they eat many kinds of insects and weeds, and do not exhaust all the food supply of one kind. Under such circ.u.mstances, too, the insect-eating birds would find plenty of insects without preying on useful products, and the insects would be held in check, so that the damage to crops would be slight.

The following are examples of the food eaten by birds and the good that they thus accomplish to man:

During the outbreak of Rocky Mountain locusts in Nebraska, a scientific observer watched a long-billed marsh wren carry thirty locusts to her young in an hour and the same number was kept up regularly. At this rate, for seven hours a day, a nest-ful of young wrens would eat two hundred and ten locusts a day. From this he calculated that the birds of eastern Nebraska would destroy daily nearly 163,000 locusts.

A locust eats its own weight in grain a day. The locusts eaten by the baby birds would therefore be able to destroy one hundred and seventy-five tons of crops, worth at least ten dollars a ton, or one thousand seven hundred and fifty dollars.

So we see that birds have an actual cash value on the farm. The value of the hay crop saved by meadow-larks in destroying gra.s.shoppers has been estimated at three hundred and fifty-six dollars on every township thirty-six miles square.

An article contributed to the New York _Tribune_ by an official in the Department of Agriculture estimated the amount of weed seeds annually destroyed by the tree sparrow in the state of Iowa on the basis of one-fourth of an ounce of seed eaten daily by each bird. Supposing there were ten birds to each mile, in the two hundred days that they remain in the region, we should have a total of 1,750,000 pounds, or eight hundred and seventy-five tons, of weed seed consumed in a single season by this one species in the one state. In a thicket near Washington, D. C. was a large patch of weeds where sparrows fed during the winter. The ground was literally black with the seeds in the spring but on examining them it was found that nearly all had been cracked and the kernels eaten. A search was made for seeds of various weeds but not more than half a dozen could be found, while many thousands of empty seed-pods showed how the birds had lived during the winter.

In no place are birds more important than in the forests, where they save hundreds of thousands of dollars worth of valuable timber each year. In forests there can be no rotation of crops and no cultivation, and spraying, which keeps down the insect pests in the orchard, is impossible here because of the expense. It would not pay to spray two or three times a year a crop of timber that requires a lifetime to grow. So in the forests the owner must depend entirely on birds for his protection. How great the destruction of our forests would be is shown by the fact that the damage at present is estimated at $100,000,000, in spite of the fact that a vast army of birds is working tirelessly, summer and winter, to devour the insects! The debt of the forester to the birds can hardly be estimated.

A full variety of birds will thoroughly protect a farm and orchard. The sparrows will destroy the weed seeds; the hawks and kites, flying by day, will catch the meadow mice and other small mammals, and the owls will pounce on those that venture forth at night. Of the insect-eating birds, the larks, wrens, thrushes and sparrows search the ground for worms, eggs and insects under leaves and logs everywhere. The nuthatches, vireos, warblers and creepers search every part of the tree, while the woodp.e.c.k.e.rs tap beneath the bark for grubs and worms. The fly-catching birds catch their insect food on the wing among the trees and branches, and, last of all, the swallows skim high in the air and catch the few insects that rise high above the tree-tops.

Thus each family has its part of the work and the good they do is almost too great to calculate. Without this check it would be impossible for any green thing to flourish. So vast an amount of food is required to feed the great army of insects that the task would be impossible in any other way.

A brief description of some of the common birds and their food habits is given here that farmers may know their friends, and that people everywhere may learn to protect the useful birds and drive out the few that do the mischief.

All of these observations have been made by field workers from the Department of Agriculture, and no statement has been made that has not been proved by the examination of many bird stomachs at different seasons.

Highest of all in the list come the bluebirds. They are among the most beautiful of our native birds, with their bright blue coats and soft red b.r.e.a.s.t.s. They are sweet singers, and are among the first to return in the spring to tell us of the return of summer. In addition to this they have many good habits and absolutely no bad ones. More than three-fourths of their food consists of insects,--beetles, gra.s.shoppers and caterpillars. The remainder is weed seeds and fruit, but there were no reports of cultivated fruits being eaten by bluebirds. On the contrary they eat the most undesirable of the wild fruit, chokeberry, pokeberry, Virginia creeper, bitter-sweet and sumac, as well as large quant.i.ties of ragweed seeds. Other birds are equally useful but none combines usefulness with so much beauty and sweetness of song.