WatchList Species Account for Bell’s Vireo (Vireo bellii)

Qualifies for the list as a Red List Species

Photo: Glen Tepke

Bell’s Vireo breeds in the Southwest, central states, and in southern coastal California, in addition to northern Mexico. It winters primarily in western Mexico south to Nicaragua.

Though it nests in early successional scrubby areas, in the Southwest and California it depends for nesting habitat on corridors of vegetation along rivers and streams. Modification of such habitat through agriculture, grazing, urbanization, and flood control and reservoir construction and heavy parasitism by cowbirds have led to steep declines in the numbers of Bell’s Vireos.

The subspecies in California, the Least Bell’s Vireo, has been classified by the U.S. Fish and Wildlife Service as endangered. Habitat restoration and cowbird control have allowed its numbers in California to recover somewhat, but its population there still numbers only in the few hundreds. Throughout its range in the U.S. its numbers have declined 2.8% per year between 1966 and 2001. Measures adopted for its conservation in California have been adopted elsewhere in the western part of its U.S. range.