Examinations of 1,236 stomachs show that 42 per cent of its food is animal matter, principally insects, while the remainder is made up largely of small fruits or berries. Over 16 per cent consists of beetles, about one-third of which are useful ground beetles, taken mostly in spring and fall when other insects are scarce. Grasshoppers make up about 5 per cent of the whole food, but in August they comprise 17 per cent. Caterpillars form about 9 per cent, while the rest of the animal food, about 11 per cent, is made up of various insects, with a few spiders, snails, and angleworms. All the grasshoppers, caterpillars, and bugs, with a large portion of the beetles, are injurious, and it is safe to say that noxious insects comprise more than one-third of the robin’s food.
Vegetable food forms 58 per cent of the stomach contents, over 42 per cent being wild fruits and only a little more than 8 per cent being possibly cultivated varieties. Cultivated fruit amounting to about 25 per cent was found in the stomachs in June and July, but only a trifle in August. Wild fruit, on the contrary, is eaten every month and constitutes a staple food during half the year. No less than 65 species of fruit were identified in the stomachs; of these, the most important were 4 species of dogwood, 3 of wild cherries, 3 of wild grapes, 4 of greenbrier, 2 of holly, 2 of elder; and cranberries, huckleberries, blueberries, barberries, service berries, hackberries, and persimmons; together with 4 species of sumac and various other seeds not strictly fruit.
The depredations of the robin seem to be confined to the smaller and earlier fruits, few, if any, complaints being made that it eats apples, peaches, pears, grapes, or even late cherries. By the time these are ripe the forests and hedges are teeming with wild fruits which the bird evidently finds more to its taste. The cherry, unfortunately for man, ripens so early that it is almost the only fruit accessible at a time when the bird’s appetite has been sharpened by a long-continued diet of insects, earthworms, and dried berries, and it is no wonder that at first the rich juicy morsels are greedily eaten.
While the robin takes some cultivated fruits, it must be remembered that, being a natural enemy of the insect world, it has been working during the whole season to make that crop a possibility, and when the fruit ripens the robin already has a standing account with the farmer for services rendered, with the credits up to this time entirely on his side.
Much has been written about the delicate discrimination of birds for choice fruit and their selection of only the finest and costliest varieties. This is contrary to observed facts. Birds, unlike human beings, seem to prefer fruit that, like the mulberry, is sweetly insipid, or that, like the chokecherry or holly, has some astringent or bitter quality. The so-called black alder, a species of holly, has bright scarlet berries tasting as bitter as quinine, that ripen late in October and remain on the bushes through November. Though frost grapes, the fruit of the Virginia creeper, and several species of dogwood are abundant at the same time, the birds have been found to eat the berries of the holly to a considerable extent. It is, moreover, a remarkable fact that the wild fruits upon which birds largely feed are those which man neither gathers for his own use nor adopts for cultivation.
Where wild fruit is not abundant, a few fruit-bearing shrubs and vines judiciously planted will serve for ornament and provide food for the birds. The Russian mulberry is a vigorous grower and a profuse bearer, ripening at the same time as the cherry. So far as observation has gone, most birds seem to prefer its fruit to any other. It is believed that a number of mulberry trees planted around the garden or orchard would fully protect the more valuable fruits.
Birds of the titmouse family, though insignificant in size, are far from being so in the matter of food habits. What they lack in size of body they more than make up in numbers of individuals. While in the case of some larger birds, as, for instance, the flicker, there is one pair of eyes to look for food for one large stomach, we have in the case of the ten times as numerous titmice an equivalent stomach capacity divided into 10 parts, each furnished with a pair of eyes and other accessories, as wings and feet. As against the one place occupied by the larger bird, 10 are being searched for food at the same time by the smaller species.
The character of the food of titmice gives a peculiar value to their services, for it consists largely of the small insects and their eggs that wholly escape the search of larger birds. Throughout the year most of the species of this group remain on their range, so that they are constantly engaged in their beneficial work, continuing it in winter when the majority of their coworkers have sought a milder clime. It is at this season that the titmice do their greatest good, for when flying and crawling insects are no more to be found, the birds must feed upon such species as they find hibernating in crevices, or upon the eggs of insects laid in similar places. In winter’s dearth of moving insects the search for such animal food as may be found is perforce thorough and unremitting.