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Least Bell's Vireo (Vireo bellii pusillus)


Characteristics: Grayish-green songbird about 4.5" in length with whitish belly, faint white eye ring, and two pale wing bars. Male and female plumages similar.

Distribution & Status: Current breeding range Southern California to northern Baja California. Winters in southern Baja California. Listed as federally endangered in 1986.

Habitat: Breeds in riparian (streamside) habitat with a layer of dense, shrubby plants under taller trees.

Feeding: Captures insects and spiders by foliage-gleaning from just above ground level to tree top. Larger prey items are held with its foot and smashed with its bill before eating.

Song: Composed of two main phrases, the first ascends and second descends.

Life Span: 3-4 years; an 8-year-old banded male is on record at San Diego River.

Behavior Notes: Males help in all phases of the nest cycle, from building the basket-like nest to incubating eggs and tending chicks. Nests commonly parasitized by Brown-headed Cowbirds.

--Sue Abbott, PRBO Education & Outreach

--Reviewed by Barbara Kus, USGS Western Ecological Research Center, San Diego

Reference: Brown B.T. 1993. Bell's Vireo. In "Birds of North America" No.35