and reaches New England early in May. The path of its northern migrations, and of its return, is somewhat in doubt. It is abundant in winter, according to Sumichrast, about Orizaba, and probably enters Texas and passes north and east along the Mississippi and the Ohio Rivers. In certain portions of the country this species is evidently on the increase, becoming more and more common as the country is settled, and towns and villages spring up.
The Warbling Vireo builds its nest usually in more elevated positions than any others of this family. For the most part in the vicinity of dwellings, often over frequented streets, they suspend their elaborately woven and beautiful little basket-like nest, secure from intrusion from their human neighbors, and protected by the near presence of man from all their more dreaded enemies. Audubon narrates, in an interesting manner, the building of their nest by a pair of these birds on a poplar-tree, near his window, in Camden, N. J. It was suspended between the body of the tree and a branch coming out at an acute angle. The pair were at work, morning and evening, eight days, first attaching slender blades of grass to the knots on the branch and the bark of the trunk, and thence working downward and outward. They varied their materials, from time to time, until at last he traced them, after a prolonged absence, to a distant haystack, from which they brought fine, slender, dry grasses, with which they completed and lined their nest.
The nests of the Warbling Vireo, while they resemble closely those of the other species in all the characteristics of this well-marked family, are yet, as a rule, more carefully, neatly, and closely built. They are usually suspended at the height of from thirty to fifty feet, in the fork of twigs, under and near the extremity of the tree-top, often an elm, protected from the sun and storm by a canopy of leaves, and quite out of reach of most enemies. They vary little in size, being about two inches in height and three and a half in their greatest diameter, narrowing, toward their junction with the twigs, to two inches. They are all secured in a very firm manner to the twigs from which they are suspended by a felting of various materials, chiefly soft, flexible, flax-like strips of vegetable fibres, leaves, stems of plants, and strips of bark. With these are interwoven, and carried out around the outer portions of the nest, long strips of soft flexible bark of deciduous trees. They are softly and compactly filled in and lined with fine stems of plants.
The eggs are usually five in number, and, like those of all the Vireos, are of a brilliant crystal-white, sparingly spotted at the larger end with markings of dark brown, and others of a lighter shade. They are less marked with spots than usual in the genus, and are often entirely unspotted, and pure white. Occasionally, however, they are found with well-marked blotches of reddish-brown. They vary in length from .75 to .70 of an inch, and average about .55 in their breadth.
Vireosylvia gilvus, var. swainsoni, Baird.
WESTERN WARBLING GREENLET.
Vireo swainsoni, Baird, Birds N. Am. 1858, 336 (Pacific coast).—Elliot, Illust. Birds N. A. I, vii. Vireosylvia swainsoni, Baird, Rev. Am. B. 343. Vireosylvia gilva, var. swainsoni, Cooper, Orn. Cal. 1, 1870, 116. Vireo bartramii, Swainson, F. B. A. II, 1831, 235 (in part; spec. from Columbia River?).
Vireo swainsoni.
12891
(No. 5,321 ♂.) Similar to V. gilva, but smaller; colors paler. Bill more depressed. Upper mandible almost black. Second quill much shorter than sixth. Total length, 4.75; wing, 2.71; tail, 2.35; difference between tenth quill and longest, .58; exposed portion of first primary, .58, of second, 1.82, of longest (measured from exposed base of first primary), 2.10; length of bill from forehead, .56, from nostril, .29, along gape, .65; depth of bill, .13; tarsus, .70; middle toe and claw, .56; hind toe and claw, .43.