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BIRDS THAT INJURE GRAIN. By F. E. L. BEAL, Assistant, Biological Survey, DAMAGE CAUSED BY BIRDS. Aside from its importance as a principal source of food supply, the immense financial value of the grain crop of the United States gives a peculiar interest to any natural agency which affects its amount or quality. For this reason much time, labor, and money have been expended in the study of the insects injurious to grain and in devis- ing methods to pire vent their ravages. But insects are not the only members of the animal kingdom that have proved destructive to this crop. Several species of birds feed at certain times upon cereals, and in some places, where these birds breed in vast numbers, their depre- dations become serious. The total value of the grain product of the United States is, in round number^, $1,000,000,000 per annum. Any agency which réduces this value by only 1 per cent involves a loss of not less than $10,000,000, a sum sufficiently large to startle a thought- ful person. Several species of birds have been accused of serious depredations upon grain—either by attacking the seed at the time of planting or soon after germination, or^ by preying upon the immature or ripened crop. In the eastern part of the country the common crow is the most conspicuous example, while in the Mississippi Valley and farther west several species of blackbirds {Icteridœ) have at times made such havoc as to cause serious apprehensions. The redwing and the yellowhead usually nest near water, and, when possible, directly over it. For this reason the prairie ponds and sloughs of the Upper Mississippi Valley, often of vast extent, afford such favorable breeding grounds that the region has become the theater of their greatest activities. It is the gathering place of the immense nocks which have often struck terror to the heart of the farmer as their countless hosts settled upon his fields. The nesting period is in May and June, and by the end of the latter month, or soon after, the young are on the wing. ^ Since this is the time when the grain begins to ripen, it is natural for the old birds to lead their young to the fields for food. The molting season follows immediately after the duties of reproduction have ended, and is a trying one to the already debilitated parents. Under these circumstances the abundant and easily obtainable supply of nutritious food afforded by the grain- fields comes to the birds like a friend in need and enables them to recruit their exhausted energies. 345 346 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. CAUSE OF INCREASED NUMBER OF BLACKBIRDS. It is highly probable that the changing of the original prairies into fields of grain has contributed to the increase of blackbirds by fur- nishing an abundant and sure supply of food at a time when it is most needed. Many instances can be pointed out where birds have increased in numbers since the settlement of the country, owing to the increased food supply resulting from cultivation; and in some cases, at least, this increase has taken place in spite of the fact that the birds were extensively shot for food. While the native prairies produced an abundance of forage for the larger ruminants and small rodents, they did not offer a great variety of plants having seeds large enough to be suitable for bird food. The immense areas of wild rice in the swamps and marshes, on the contrary, furnished a bountiful supply upon which' the birds originally subsisted. Cultivation did not disturb this source of supply, but added another far more pro- ductive, and one which ripened at a considerably earlier date; for wild rice does not mature till September, while wheat and oats are available in July, and winter rye and wheat in June. Under these circumstances a great increase in the number of birds would seem to be a foregone conclusion, and in many States^ notably those of the Mississippi Valley, the various species of blackbirds have at various times and placets exceeded the number required to fulfill thé best economic conditions, and the result has been to a greater or less extent disastrous. It does not necessarüy follow that these birds are wholly harmful to the interests of man; it merely shows that it is possible to have too many of them, that is, too many of the partic- ular species which feed so largely on grain. In States where these birds are less abundant but little damage is done. An investigation of the food habits of blackbirds shows that during the breeding months, and also to some extent during the entire warm season, all of the species subsist largely on insects. When this is considered in connection with the fact that many of the species feed largely upon seeds of troublesome weeds, especially in winter, there is reason to believe that they really subserve a useful purpose in the economy of nature. They only become harmful when, by increasing out of proportion to their environment, the proper balance of organ- isms is disturbed. THE MORE IMPORTANT GRAIN-EATING BIRDS. In the following pages some of the more important species of grain- eating birds are discussed, and their special ravages pointed out. - THE CROW. The common crow {Corvics americanits) ranges over the United States east of the Great Plains, more sparingly over the rest of the country, and to the northward extends beyond our borders. East of the Alleghany Mountains, and especially in the Kew England and BIRDS THAT INJURE GRAIN. 347 other Atlantic States, the crow has long been known as a "thief of cornfields," having been so christened by the aboriginal inhabitants. The greatest damage is done in spring, when the birds pull up the sprouted grain. Dry, hard corn is not palatable food for the crow, as has been shown by experiments with a caged bird. In seasons of scarcity ripe corn is sometimes eaten, but is not preferred. Corn that has been softened and sweetened by the process of germination, on the contrary, is a favorite food and is eagerly sought. In the earlier days, when crows were more numerous and cornfields less so, the farmers had a constant struggle during the first two or three weeks after the corn appeared above the ground to save it from the crows. Various devices in the way of scarecrows were designed to frighten the marauders away, but most of them were only indifferently suc- cessful. More recently the plan of coating the seed corn with tar has been extensively used, and with better results. In the experi- ence of the writer, not a single kernel of tarred corn was disturbed, while rows of untarred seed immediately adjoining were almost entirely destroyed. It has been asserted by some people that the crow pulls up corn not for the sake of the kernel, but for the grubs that may be found in the manure about the roots. Careful investiga- tion has disproved this assertion. Crows do eat the sprouted kernels, although they also devour grubs unearthed at the same time, for they are great lovers of insects and their larvse. But the result to the farmer is the same, and it is poor consolation to know that if the corn had not been eaten by the crow it would have been killed by the grub. Some complaints have also been made that crows eat corn in the " milk " or " roasting-ear " stage, and from that time on until it is ripe. It is evident that much more extensive ravages would be necessary at this stage to cause as much damage as that incident to pulling the sprouted seed. As a matter of fact, reports do not indicate extensive injury of this kind. In the Mississippi Valley the crow does not appear to have attracted so much attention as in the East. During a residence of eight years in Iowa the writer never heard any complaints of injury to grain, nor did he observe any cases of this kind. Yet, some damage has been done, and instances of serious loss are on record, usually, however, arising from tearing open the husks and pecking the soft kernels. In these cases the ears thus opened are exposed to the weather, and often rot from being wet by rains. Food habits of the crow.—Investigations of the food habits of the crow, based on an examination of the contents of 909 stomachs,^ show 1" The Common Crow of the United States," by Walter B. Barrows and E. A, Schwarz, Bulletin No. 6, Division Ornithology and Mammalogy, U. S. Department ef Agriculture, 1895. 348 YEARBOOK OF THE DEPARTMENT OP AGRICULTURE. that about 29 per cent of the food for the year consists of grain, of which corn constitutes something more than 21 per cent, the greatest quantity being eaten in the three winter months. All of this must be either waste grain picked up in fields and roads, or corn stolen from cribs or shocks. A good deal is taken also in the three fall months, when corn is soft; and May, the month of sprouting corn, shows a slight increase over the other spring and summer months. The two months of July and August are the only ones in which wheat is eaten to any important extent. Only small quantities of other grains are taken. On the other hand, the loss of grain is offset by the destruction of insects. These constitute more than 23 per cent of the crow's yearly diet, and the larger part of them are noxious.

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