This is the “default” Myiarchus throughout much of the west. Monotypic. Length 7.6–8.6".
Adult: relatively small, slender; moderately long tailed. Whitish gray throat, pale gray breast with whitish transition to pale yellow belly. Brown crown and brownish gray back separated by subtle gray collar. Blackish brown wings with 2 whitish wing bars; rufous-edged primaries; secondaries edged white to pale yellow. Outer pairs of tail feathers extensively rufous on inner webs; dark shaft stripe flares at tip so that rufous does not extend to feather tips. Some lack typical tail pattern, and pattern can vary among feathers. All-dark bill is relatively thin, short to medium length. Mouth lining flesh-color. Juvenile: duller and paler; browner above; belly more whitish yellow; rufous-edged secondaries; tail predominantly rufous with dark shaft stripes on outer webs. Some juvenile middle secondaries or tail feathers can be retained into first basic plumage.
Superficially identical to the brown-crested, which averages darker gray and brighter yellow below, is larger in all aspects, lacks typical ash-throated tail pattern, and has different voice. Juvenile ash-throated tail suggests the great crested, but size, shape, and plumage should make identification easy. Nutting’s best separated by voice, mouth color.
Call: ka-brick, soft prrrrt (nonbreeders less vocal). Dawn song: a repeated series of ha-wheer and other notes.
Status and Distribution
Common. Breeding: desert scrub and riparian, oak, or coniferous woodland. Migration: in spring, mid-March–mid-May. In fall, August–mid-September; stragglers October–November. Winter: extreme southwestern United States to Honduras. Vagrant: rare/casual north to southwestern British Columbia, east to southeastern Canada and to Atlantic and Gulf coasts in the United States, mainly in fall and winter.
—From the National Geographic book Complete Birds of North America, 2006