Field Guide to Birds of North America
Cassin's Vireo
General
Cassin's Vireo: Small vireo with olive-gray upperparts, white underparts, and pale yellow flanks. Head is gray with white eye-ring that extends to brow. Wings are dark with two white bars. Female is slightly duller. Juvenile has less gray on crown and sides of head.
Range and Habitat
Cassin's Vireo: Breeds from British Columbia and southwestern Alberta south to central Idaho and along the west coast to southern California. Most leave the U.S. in fall but a small number spend winter in southeastern Arizona; prefers dry, open forests in mountains and foothills.
Listen to Call
Voice Text
"chreuÂ… ch'reeÂ… choo'reet" or "chreeÂ… ch-ri'chi-roo"
Interesting Facts
The Cassin's Vireo was formerly lumped as a "Solitary Vireo," along with the Plumbeous and Blue-headed vireos, it is now considered a separate species.
Two subspecies are recognized. One is widespread in western North America from Canada to the northern part of Baja California. The other is found only on the very southern tip of Baja California more than 500 miles away.
It is a fearless defender of its nest. Both the male and female will vigorously scold a predator and dive at it. The female often will not leave her nest and sometimes can be picked up off of it by a human observer.
A group of vireos are collectively known as a "call" of vireos.
Author
|
Family
Vireos and Allies (Vireonidae)_blue
|
Species
Vireo cassinii
|
Length4 - 6
Inches
|
Wingspan8.5
Inches
|
Cassin's Vireo
Cassin's Vireo: Small vireo, olive-gray upperparts, white underparts, pale yellow flanks. Head is gray with white eye-ring that extends to brow. Wings are dark with two white bars. Until the 1990s was classified as the Solitary Vireo, along with the Blue-headed and Plumbeous Vireos.
● Song: "chreuÂ… ch'reeÂ… choo'reet" or "chreeÂ… ch-ri'chi-roo"
● Foraging & Feeding: Cassin's Vireo: Eats insects and fruits. Forages high in trees by gleaning food from bark, branches, or foliage, sometimes hovering briefly to pick food off vegetation or catch insects in flight.
● Breeding & nesting: Cassin's Vireo: Three to five creamy white eggs with black and brown speckles are laid in a nest made of twigs, fine grass, and stems, lined with finer grass and hair, and built 4 to 30 feet above the ground in a tree or bush. Incubation ranges from 11 to 12 days and is carried out by both parents.
● Similar species: Cassin's Vireo: Blue-headed Vireo has blue-gray crown contrasting more sharply with throat and back. Plumbeous Vireo lacks green hues except on rump, yellow edges on flight feathers, and yellow on flanks. Hutton's Vireo is smaller with incomplete eye-ring, dingier underparts, and less contrasting plumage. Bell's Vireo lacks full eye-ring and has weaker wing-bars.
Flight Pattern
Somewhat weak fluttering direct flight on rapidly beating wings. May hover briefly to pick insect or fruit off vegetation.
|
BreedingMonogamous, Solitary nester
|
PopulationFairly common
|
MigrationMigratory
|
Weight0.5 - 0.6
Ounces
|