_Behavior._--A marked characteristic of Townsend's warblers is their fondness for the tree tops, especially on their breeding grounds and to some extent at other seasons. In the coniferous forests which they frequent in summer, they confine their activities almost entirely to the tops of the tallest fir trees, where they travel rapidly, stopping only long enough to glean their food and then hastening onward, returning, perhaps, over the same trees in their active restless foraging. Later in the summer and as migration time draws near, they are frequently seen at lower levels, among deciduous trees and in second growth woods, often in association with kinglets, chickadees, other warblers, and juncos. _Voice._--Mrs. Allen (MS.) renders the song as a "_weazy weazy weazy weazy tweea_, rising in spirals, and the call-note a soft _chip_, not so metallic as the lutescent's, and less emphatic than the Audubon's." According to Rathbun (MS.), "its song is heard during May and June quite persistently under all climatic conditions." Dr. Merrill (1898) says that the song, as he heard it in Idaho, "usually consists of five notes, _deé deé deé--d[=e] d[=e]_, all, especially the first three, uttered in the peculiar harsh drawl of _D. virens_. Later in the season this song changes somewhat." This second song was heard in low second growth. Mr. Rathbun also refers in his notes to a different song, heard in some young second growth; the bird was "singing softly as if to itself, this being a much more finished performance than the ordinary song, although identical in construction, the distinction being an elaboration of the song in full in softer tones." Ralph Hoffmann (1927) found the song of Townsend's warbler difficult to distinguish from that of the black-throated gray warbler. "The Townsend Warbler's song has less of the drawling inflection in the opening notes than the Black-throated Gray's and often ends with a prolonged _ee-zee_. A song noted by the writer in the Olympics in western Washington was transcribed as a hoarse _swee swee swee zee_." _Field marks._--The adult male Townsend's warbler is distinctively marked, having the crown, cheeks, and throat black, with bright yellow spaces between these areas, and an olive-green back and bright yellow breast, both streaked with black; it has two prominent white wing bars and considerable white on the outer tail feathers. The female has a similar pattern, but the colors are much duller and she has no black throat. Young and adults in the fall are much like the adult female in spring, but are more or less clouded with brownish. There is no other western warbler that is much like it.