HABITS. The Blue Yellow-Back is one of our most interesting and attractive Warblers. Nowhere very abundant, it has a well-marked and restricted area within which it is sparingly distributed. It is found from the Mississippi Valley to the Atlantic, and from Canada southward. In its winter migrations it visits the West Indies, the Bahamas, and Central and South America. Halifax on the east, and Platte River on the west, appear to be the northern limit of its distribution. Dr. Woodhouse met with it in the Indian Territory during the breeding-season. Mr. Alfred Newton found this species, apparently only a winter visitant, in the island of St. Croix. Most of the birds left about the middle of March, though a few remained until early in May. A single specimen of this species was taken at South Greenland in 1857. This Warbler has been found breeding as far to the south as Tuckertown, N. J., by Mr. W. S. Wood; and at Cape May, in the same State, by Mr. John Krider. At Washington, Dr. Coues found it only a spring and autumn visitant, exceedingly abundant from April 25 to May 15. Possibly a few remained to breed, as he met with them in the first week of August. In the fall they were again abundant from August 25 to the second week in October. He found them inhabiting exclusively high open woods, and usually seen in the tops of the trees, or at the extremities of the branches, in the tufts of leaves and blossoms. Even where most common it is not an abundant species, and is to be found only in certain localities, somewhat open and swampy thickets, usually not of great extent, and prefers those well covered with the long gray lichens known as Spanish moss. In such localities only, so far as I know, do they breed. This Warbler has also been ascertained to breed in Southern Illinois, where Mr. Ridgway found it in July, engaged in feeding fully fledged young birds. It is there most common in spring and fall. A true Warbler in most of its attributes, this bird has many of the habits of Titmice. Like these it frequents the tops of the taller trees, feeding on the small winged insects and caterpillars that abound among the young leaves and blossoms. It has no song, properly so called, its notes are feeble and few, and can be heard only a short distance. The song of this species is said by Mr. Trippe, of Orange, N. Y., to be a somewhat sharp and lisping, yet quite varied and pleasing, series of notes. Mr. Audubon speaks of this species as breeding in Louisiana, but his description of the nest differs so entirely from such as are met with in Massachusetts as to suggest doubts as to the correctness of the identification. He describes them as flitting over damp places, the edges of ponds and streams, and pursuing their prey with great activity. They resort to the woods as soon as the foliage appears on the forest trees, and glean among the leaves for the smaller winged insects.