Cassin's Vireo

SCIENTIFIC NAME: Vireo cassinii

Cassin's Vireo

The Cassin’s Vireo is a small North American songbird with a fairly thick, short bill and relatively long wings and tail.

Both sexes are 4.3 – 5.3 inches long, with 9.4 inches wingspan and weight of 13 – 18 grams.
It is olive green above with a gray head and a prominent white eyering and wingbars.
It is white below, with yellow-olive wash on the sides.
Eyes, bill and legs are dark.

CALL: Harsh, raspy alarm calls like “cha-cha-cha-cha” that vary in intensity and duration. It is amongst the most often heard vocalizations outside its breeding season.

SONG: Consists of short, rough whistled phrases of several notes, spaced about 2 seconds apart, which is given persistently. The phrases often alternate ending on a high note and a low note, giving an impression of question and answer.

Feeds almost exclusively on insects and spiders during summer.
Fruits and seeds are consumed mostly in winter.

Prefers open woodlands of the western mountains and foothills, and is usually found in the middle to lower portions of the forest canopy, where it slowly and deliberately forages for insects among the foliage.

Ranges from southern British Colombia in Canada through the western coastal states of the United States.

It is a migratory bird.
Winters from southern Arizona (the Sonoran Desert) to southern Mexico.

Both the male and female build a bulky, messy-looking cup-shaped nest that is suspended from a fork in the branches.
It is made of leaves, grasses and moss and lined with grasses, plant fibers and hair.
The female lays 3 – 5 whitish eggs with a few brown spots around the large end.
Incubation lasts for about 12 – 14 days, by both parents.



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