This Vireo, like all of its peculiar and well-marked genus, prefers the forests or the tops of large and shady trees, obtains its food usually among, their upper branches, and very rarely approaches the ground. It is not exclusively sylvan, as at times it may be found around dwellings, hunting for insects and spiders; and although it hunts for food among the tree-tops, its nest is not always in such high situations, often not more than four or five feet from the ground.
In their migrations these birds enter the United States early in March, but do not make their appearance in Pennsylvania until the last of April, or in New England until the middle of May.
The Vireos procure their food, for the most part, by moving about and along branches, and among the twigs of trees, hopping from one position to another, and securing their prey without the click of a Flycatcher. The insects they capture are usually not in motion, though occasionally they will take them on the wing. They also feed on several kinds of ripe berries in the autumn.
The song of this Vireo is loud, musical, simple, and pleasing. It is uttered in short, emphatic bars, and at times has a very marked resemblance to the melodious chant of the Robin, though without its volume and power. This Vireo is one of the earliest of our spring musicians, as it is also one of the most constant and untiring in its song, continuing to sing long after most of the other vocalists have become silent, and even until it is about to leave us, at the close of September. The tender and pathetic utterances of this Vireo, uttered with so much apparent animation, to judge from their sound,
are in striking contrast to the apparent indifference or unconsciousness of the little vocalist who, while thus delighting the ear of the listener, seems to be all the while chiefly bent on procuring its daily supply of food, which it pursues with unabated ardor.
This Vireo builds the neat pensile nest of its race, suspending it from the fork of two or more twigs of a forest tree, at various heights of from five to fifty feet from the ground. It is cup-like in shape, and always dependent from small twigs, around which its upper edges are firmly bound. Externally it is woven of various materials, fine strips of bark, the hempen fibres of vegetables, and webs of spiders and of various caterpillars. These are compactly pressed and woven, and, as some suppose, agglutinated by the saliva of the builder. Sometimes the unmanageable materials give to the outside of the nest a rude and unfinished appearance, at others they are evenly and smoothly wrought. They are very strong, uninjured by the storms of winter, and are often made use of by other birds, by mice, and even by the same bird a second season.
A nest of this bird (S. I. Coll., 3,353) was obtained at the Cumberland House by Mr. Kennicott. It is pensile, like all others, but is composed almost exclusively of pine-needles,—a dry and hard material, difficult of management in making such a nest. With these are intermingled a few bits of moss, fine strips of bark, and flax-like vegetable fibres. Within this rude basket is an inner nest, made up of fine dry grasses, strips of bark, and pine leaves. The external fabric is loosely put together,—an unusual feature,—but the inner portion, in the firmness and strength with which it was made, is in remarkable contrast.
The Red-eyed Vireo’s nest is often chosen by the Cowbird for the deposition of her parasitic eggs, and these foster-parents are singularly devoted in the care of their alien guests, whom they tenderly nurture, even to the neglect of their own offspring. In one instance three eggs of a Cowbird were deposited in the nest of the Vireo before any of her own, and, without laying any, the female Vireo proceeded to sit upon and hatch the intruders. In another case, where two of the Vireo’s had been laid, two Cowbird’s eggs were added. The Vireo stopped laying, and proceeded to incubate. In each instance the female Vireo seemed to forego her own natural aspirations, and at once conform to the new situation.
The male Vireo often evinces great courage and spirit in the defence of his nest, when the young are hatched driving away intruders, and even flying in the face of a man who approaches too near.
Mr. Nuttall states that the young of the Red-eyed Vireo feed eagerly upon the berries of the cornel and the Viburnum dentatum, and other shrubs. A young bird kept in confinement soon became very gentle, and readily ate flies and grasshoppers from his hand, and viburnum berries. A tame Kingbird in the same room was very jealous of and tyrannized over him, so as to compel him to seek protection from his captor. The Vireos, like Flycatchers,