Cassin's vireo is a small North American songbird, ranging from southern British Columbia in Canada through the western coastal states of the United States, including California, Oregon, and Washington. The Cassin's Vireo moves down Western United States forests in its migration. During its migration in early spring and late fall, it spends the winter in regions from southern Arizona to southern Mexico, including parts of Baja California and the Pacific coast of Mexico.
Region
Western North America
Typical Environment
Breeds from southern British Columbia through Washington, Oregon, and California, especially along the Pacific slope and in the Cascades and Sierra Nevada foothills. Occurs in open coniferous and mixed woodlands, oak woodlands, and forest edges with a well-developed mid-canopy. During migration it moves through a variety of wooded habitats across the western United States. Winters from southern Arizona and Baja California south along the Pacific slope of Mexico to at least southern Mexico. It favors riparian corridors and semi-open forests during the nonbreeding season.
Altitude Range
Sea level to 2500 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
Cassin's vireo was once lumped with Blue-headed and Plumbeous vireos as the 'Solitary Vireo' before being split based on vocal and plumage differences. It shows a distinctive 'spectacled' face with a white eye ring connected by a white lore line. The species weaves a delicate hanging cup nest using grasses, bark strips, and spider silk. It forages methodically in the mid-canopy, often joining mixed-species flocks outside the breeding season.
Temperament
solitary and territorial
Flight Pattern
short rapid wingbeats with brief glides; occasional short sallies
Social Behavior
Breeding pairs are territorial and typically monogamous, placing a suspended cup nest in a fork of a branch in the mid-canopy. Both sexes participate in nest building and incubation. Outside the breeding season, individuals often join mixed-species flocks while foraging. Nesting occurs from late spring through summer depending on latitude and elevation.
Migratory Pattern
Seasonal migrant
Song Description
A deliberate series of burry, mellow phrases delivered at even intervals, often alternating up- and down-slurred notes. Phrases sound conversational, with clear pauses between them. Calls include soft cheks and scolds when agitated.
