Part 4

Perhaps the most important and interesting insect found was the black olive scale, which occurred in 24 stomachs and amounted to a little more than 18 per cent of the food. In addition a number of the stomachs were more or less filled with another scale, which was not further identified. A number of small snout beetles (weevils) were eaten and some small caterpillars; there were also the remains of a spider.

The vegetable food of the species seemed to consist mostly of seeds, but they were so broken up as to defy recognition. A little fruit pulp and a little mast were also found.

Among the stomachs of the bush tits examined were those of one brood of eight nestlings about 10 days old. The vegetable matter in these stomachs was only three-fourths of 1 per cent and consisted of one seed and some rubbish. The animal matter was made up of beetles, wasps, bugs, caterpillars and pupæ, and spiders. The greatest interest lies in the fact that every one of these stomachs contained pupæ of the codling moth, on an average of over five to each. The oak tree in which these birds were found was in a belt of timber near a neglected orchard which the parent birds used as a foraging ground, and they did their best to remedy the neglect of the owner. As feeding and digestion in the case of nestling birds is almost continuous during the hours of daylight, the above record would be several times repeated during a day’s feeding. There were probably not less than a dozen nests of the bush tit along the border of this orchard, and these birds must have exerted a great restrictive influence upon the increase of the codling moth, as well as of other insects in that vicinity.

THE WRENS.

The diminutive house wren (fig. 4) frequents barns and gardens, and particularly old orchards in which the trees are partially decayed. He makes his nest in a hollow where perhaps a woodpecker had a domicile the year before, but he is a pugnacious character, and if he happens to fancy one of the boxes put up for bluebirds, he does not hesitate to take it. He is usually not slow to avail himself of boxes, gourds, tin cans, or empty jars placed for his accommodation.

Troglodytes aëdon.

In food habits the house wren is entirely beneficial. He may be said to live upon animal food alone, for an examination of 88 stomachs showed that 98 per cent of the contents was made up of insects or their allies, and only 2 per cent was vegetable food, including bits of grass and similar matter, evidently taken by accident with the insects. Half of this food consisted of grasshoppers and beetles; the remainder of caterpillars, bugs, and spiders. As the wren is a prolific breeder, frequently rearing in a season from 12 to 16 young, a family of these birds must cause considerable reduction in the number of insects in a garden. Wrens are industrious foragers, searching every tree, shrub, and vine for caterpillars, and examining every post and rail of the fence and every cranny in the wall for insects or spiders.

The house wren is only one of a numerous group of small birds of similar habits. There are within the limits of the United States 28 species and subspecies of wrens, occupying more or less completely the whole country from the Atlantic to the Pacific. With the exception of the marsh wrens, they all appear to prefer some cosy nook for a nesting site, and, as it happens, the farm buildings afford just the place desired. This has led several of the wrens to seek out the habitations of man, and he is benefited by their destruction of noxious insects. No species of wren has been accused of harm, and their presence should be encouraged about every farm, ranch, village, or suburban residence.

Telmatodytes palustris.

BROWN THRASHER.

The brown thrasher (fig. 5) breeds throughout the United States east of the Great Plains, and winters in the South Atlantic and Gulf States. It occasionally visits the garden or orchard, but nests in swamps or in groves standing upon low ground. The thrasher’s favorite time for singing is in early morning, when, perched on the top of a tall bush or low tree, it gives an exhibition of vocal powers which would do credit to a mocking bird. Indeed, in the South, where the latter bird is abundant, the thrasher is known as the sandy mocker.

Toxostoma rufum.

The food of the brown thrasher consists of both fruit and insects. An examination of 636 stomachs showed 36 per cent of vegetable and 64 of animal food, practically all insects, and mostly taken in spring before fruit was ripe. Half the insects were beetles and the remainder chiefly grasshoppers, caterpillars, bugs, and spiders. A few predacious beetles were eaten, but on the whole the work of the species as an insect destroyer may be considered beneficial.

Eight per cent of its food is made up of fruits like raspberries and currants which are or may be cultivated, but the raspberries at least are as likely to belong to wild as to cultivated varieties. Grain, made up mostly of scattered kernels of oats and corn, is merely a trifle, amounting to only 3 per cent. Though some of the corn may be taken from newly planted fields, it is amply paid for by the destruction of May beetles which are eaten at the same time. The rest of the food consists of wild fruit or seeds. Taken all in all, the brown thrasher is a useful bird, and probably does as good work in its secluded retreats as it would about the garden, for the swamps and groves are no doubt the breeding grounds of many insects that migrate thence to attack the crops of the farmer.

CATBIRD.

The catbird (fig. 6), like the thrasher, is a lover of swamps and delights to make its home in a tangle of wild grapevines, greenbriers, and shrubs, where it is safe from attack and can find its favorite food in abundance. It is found throughout the United States west to the Rocky Mountains, and extends also from Washington, Idaho, and Utah northward into the provinces of Canada. It winters in the Southern States, Cuba, Mexico, and Central America.

Dumetella carolinensis.

Reports from the Mississippi Valley indicate that the catbird is sometimes a serious annoyance to fruit growers. The reason for such reports may possibly be found in the fact that on the prairies fruit-bearing shrubs, which afford so large a part of this bird’s food, are conspicuously absent. With the settlement of this region comes an extensive planting of orchards, vineyards, and small-fruit gardens, which furnish shelter and nesting sites for the catbird as well as for other species. There is in consequence a large increase in the numbers of the birds, but no corresponding gain in the supply of native fruits upon which they were accustomed to feed. Under these circumstances what is more natural than for the birds to turn to cultivated fruits for their food? The remedy is obvious: Cultivated fruits can be protected by the simple expedient of planting the wild species which are preferred by the birds. Some experiments with catbirds in captivity show that the Russian mulberry is preferred to any cultivated fruit.

The stomachs of 645 catbirds were examined and found to contain 44 per cent of animal (insect) and 58 per cent of vegetable food. Ants, beetles, caterpillars, and grasshoppers constitute three-fourths of the animal food, the remainder being made up of bugs, miscellaneous insects, and spiders. One-third of the vegetable food consists of cultivated fruits, or those which may be cultivated, as strawberries, raspberries, and blackberries; but while we debit the bird with the whole of this, it is probable—and in the eastern and well-wooded part of the country almost certain—that a large part is obtained from wild vines. The rest of the vegetable matter is mostly wild fruit, as cherries, dogwood, sour gum, elderberries, greenbrier, spiceberries, black alder, sumac, and poison ivy. Although the catbird sometimes does considerable harm by destroying small fruit, it can not on the whole be considered injurious. On the contrary, in most parts of the country it does far more good than harm.

THE SWALLOWS.

Seven common species of swallows are found within the limits of the United States, four of which have abandoned to some extent their primitive nesting habits and have attached themselves to the abodes of man.

In the eastern part of the country the barn swallow (fig. 7) now builds exclusively under roofs, having entirely abandoned the rock caves and cliffs in which it formerly nested. More recently the cliff swallow has found a better nesting site under the eaves of buildings than was afforded by the overhanging cliffs of earth or stone which it once used and to which it still resorts occasionally in the East and habitually in the unsettled West. The martin and the white-bellied, or tree, swallow nest either in houses supplied for the purpose, in abandoned nests of woodpeckers, or in natural crannies in rocks. The northern violet-green swallow, the rough-winged swallow, and the bank swallow still live in practically such places as their ancestors chose.

Hirundo erythrogastra.

Petrochelidon lunifrons.

Progne subis.

Iridoprocne bicolor.

Tachycineta thalassina.

Stelgidopteryx serripennis.