Within the boundaries of the United States are some 17 species of titmice, with nearly as many races or subspecies, so that there is no portion of the country lacking one or more forms. The western coast region is peculiarly rich In representatives of the family. In the eastern portion of the country the best-known and most widely distributed species is the common black-capped chickadee[8] ([fig. 3]). This bird, or some of its subspecies, occupies the whole of that part of the United States north of the latitude of Washington and extends into Canada. It is a prolific breeder, usually rearing from six to eight young in a brood.
[8] Penthestes atricapillus.
Fig. 3.—Black-capped chickadee. Length, about 5¼ inches.
Examination of 289 stomachs of this chickadee shows that its food consists of 68 per cent animal matter (insects) and 32 per cent vegetable matter. The former is made up of small caterpillars and moths and their eggs. Prominent among the latter are the eggs of the tent caterpillar moths, both the orchard and forest species. As these are two of our most destructive insects, the good done by the chickadee in devouring their eggs needs no comment. During the winter the chickadee’s food is made up of larvæ, chrysalids, and eggs of moths, varied by a few seeds, but as spring brings out hordes of flying, crawling, and jumping insects, the bird varies its diet by taking also some of these. Flies and bugs are the favorites until the weather becomes quite warm, when beetles and small wasps also are enjoyed. Among the bugs may be mentioned the plant lice and their eggs which are eaten in winter. The beetles nearly all belong to the group of snout beetles, more commonly known as weevils. These insects are mostly of small size, and nearly all are known to the farmer or fruit raiser as pests. Seventeen of them were found in one stomach. Grasshoppers do not at any time constitute an important element of the food of the chickadee, as they are too large for so small a bird; moreover, they are for the most part terrestrial Insects, while the bird is essentially arboreal. Small wasps and ants are eaten to some extent Spiders constitute an Important element of the food and are eaten at all times of the year, the birds locating them when they are hibernating in winter, as well as when they are active in summer. The vegetable food of the chickadee consists largely of small seeds, except in summer, when they are replaced by pulp of wild fruit. The wax from the seeds of poison ivy Is eaten during the winter months, but the seeds themselves are not taken. In this respect the chickadee differs from most other birds, which swallow the seeds whole; these, after digesting the wax, pass the seeds through the alimentary canal, or regurgitate them, and so scatter them broadcast to reproduce the noxious plants.
In the southern part of the country the Carolina chickadee[9] and the tufted tit[10] replace the black-cap, but their food habits are so similar that there is practically no difference in the work done. In the West several other species occur; one of the most interesting is the bush tit[11] which, with several subspecies, occupies the whole Pacific coast region. They are active, social little creatures, and except for a short time during the breeding season are found in flocks, flitting from tree to tree, busily hunting for Insects and their eggs. The contents of 66 stomachs of these birds were found to consist mostly of injurious insects to the extent of 83 per cent. Of these the most important was a small hemipterous insect which amounted to more than half of the stomach contents. These insects are of considerable economic importance, as they frequently infest grapevines and other plants to a harmful extent Several stomachs were almost exclusively filled with these minute creatures, some containing as many as 100 individuals.
[9] Penthestes carolinensis.
[10] Bæolophus bicolor.
[11] Psaltriparus minimus.