The food of Swallows, remarks Professor Beal, "consists of many small species of beetles which are much on the wing, many species of diptera (mosquitoes and their allies), with large quantities of flying ants and a few insects of similar kinds. Most of them are either injurious or annoying, and the numbers destroyed by Swallows are not only beyond calculation, but almost beyond imagination."
The true Waxwings, (Family Ampelidæ) number only three species with representatives in the northern parts of both hemispheres. Their notes, as a rule are limited to a few unmusical calls, which, with our Cedar Waxwing, are usually uttered when the bird is about to fly.
Waxwings are found in small flocks during the greater part of the year and roam about the country as though they were quite as much at home in one place as in another, provided food be plenty. Small fruits, chiefly wild ones, constitute their usual fare, but they also feed on insects, the injurious elm beetle being among their victims.
The Shrikes, (Family Laniidæ) are represented in America by only two species, the remaining two hundred or more members of this family being found in the Old World. Shrikes are noted for their singular habit of impaling their prey on thorns or similarly sharp-pointed growths, or occasionally they may hang it in the crotch of a limb. This proceeding enables them to tear it to pieces more readily, for it will be observed that while Shrikes have a hawk-like bill, their feet are comparatively weak and sparrow-like and evidently of no assistance to them in dissecting their food.
Our Northern Shrike, or Butcherbird, feeds chiefly on small birds and mice, while the southern species, or Loggerhead, is a great destroyer of grasshoppers and he also eats lizards and small snakes.
The Vireos, (Family Vireonidæ) number fifty species, all American. They search the foliage carefully for leaf-eating insects and their eggs, and examine the crevices in the bark for eggs of the injurious wood-boring insects. They are therefore unusually beneficial birds.
Bearing a general resemblance in size and color to many of the Warblers, Vireos are sometimes confused with members of that family. They are, however, as a rule, more deliberate in their motions and not such active flutterers as are many of the Warblers. They are also more musical, all the Vireos having characteristic songs, which if not always highly musical, are generally noticeable, pronounced and unmistakable.
The nests of all our Vireos are pendant, deeply cup-shaped structures usually hung between the forks of a crotch, to the arms of which they are most skilfully woven.
The Warblers, (Family Mniotiltidæ) like the Vireos are distinctly American birds, indeed they may be called characteristic North American birds since most of the one hundred odd species are found north of Mexico. Between thirty and forty species of these active, beautiful little creatures may be found in the course of a year at a single locality in the Eastern States and they therefore constitute an exceedingly important element in our bird-life. Most of them come in May at the height of the spring migration; when the woods often swarm with them as they flit from limb to limb in pursuit of their insect food. The larger number of them pass onward to their northern homes and in September they return to us in increased numbers.
The beauty of their plumage, the briefness but regularity of their visits, the rarity of certain species, combine to make the Warblers especially attractive to the field student and their charms are heightened by the difficulty with which many of them are identified. Study them as we may there are still species which have escaped us.