The western counterpart of the Blue-headed Vireo; adult has gray head fading into white throat, white eye ring and supraloral stripe with relatively thick, slightly hooked bill. Upperparts are olive to fairly bright greenish, with two narrow pale wing bars. Flight feathers show light yellow-green margins. Underparts are mostly white, with greenish or yellow-green flanks. Blue-headed Vireo is slightly brighter overall, with stronger contrast between dark blue-gray hood and white throat, and the head and rich green back. Plumbeous Vireo is gray overall, lacking greenish tones. The three were formerly considered conspecific under Solitary Vireo. Note that Cassin's is brightest in fall, when the head-to-back and head-to-throat occasionally causes misidentification as vagrant Blue-headeds.

Length: 14 (cm) Wingspan: 24 (cm)

Voice:

Halting, slow, throaty phrases, each with two or three notes that are mostly slurred downward. Song is raspier in quality than that of the Blue-headed. Call is a harsh, scolding note.

Habitat:

Dry woodlands, pine forests, oaks, mixed woods, riparian areas; especially with some large trees. During migration and winter, occurs in a wide variety of wooded areas.

Behavior:

Nest is an intricately woven cup, anchored and suspended from a forked tree branch. During winter and migration, sometimes joins flocks with other vireos, warblers, and flycatchers.

Feeding:

Forages by gleaning foliage at all levels of canopy, rarely to the ground; eats a variety of insects and occasional fruit.