Species Profile
Least Bell's Vireo
Species Details
Common NameLeast Bell's Vireo
Scientific NameVireo Bellii Pusillus
Federal Listing StatusEndangered
Federal Regulating AgencyU.S. Fish and Wildlife Service
State Listing StatusEndangered (CA)
State Regulating AgencyCalifornia Department of Fish and Game
IUCN Red List StatusNear Threatened
Relevant International RegulationMigratory Bird Treaty Act (Applicable to Canada and Mexico)
- Brook Forest Conservation/Mitigation Bank
- Pilgrim Creek Mitigation Bank
- Rancho Jamul Mitigation Bank
- Rancho San Diego Mitigation Bank

Species Range
Historically, the Least Bell's Vireo was a common to locally abundant species in lowland riparian habitat, ranging from coastal southern California through the Sacramento and San Joaquin Valleys as far north as Red Bluff (Tehama County). Populations also occurred in the foothill streams of the Sierra Nevada and Coast Ranges, and in Owens Valley, Death Valley, and scattered locations in the Mojave Desert. Least Bell's Vireos winter in southern Baja California, Mexico. Unlike during the breeding season, they are not limited in winter to willow-dominated riparian areas, but occupy a variety of habitats including mesquite scrub within arroyos, palm groves, and hedgerows bordering agricultural and residential areas.
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