Justification This species has undergone moderately rapid declines and hence is considered to be Near Threatened.

Family/Sub-family Vireonidae

Species name author Audubon, 1844

Taxonomic source(s) AOU checklist (1998 + supplements), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

1,500,000

decreasing

2,640,000 km²

No

Range & population Vireo bellii summers in central and south-western USA and northern Mexico. Its winter range extends from south Baja California along the west coast of Central America, through Mexico, El Salvador, Guatemala, Nicaragua and Honduras¹. The species has shown a decline of 2.7% per year since 1966⁴.

Ecology: It frequents dense, low, shrubby vegetation in its breeding range where it has been extensively studied¹. However, very little is known about its density, ecology or habitat use in the winter grounds.

Threats Habitat loss and modifications through agricultural spread, logging and housing developments have caused declines and continue to threaten the species. Secondarily, rates of brood parasitism by Brown-headed Cowbirds (Molothrus ater), have caused reductions in breeding populations in south-west USA¹.

Conservation measures underway Trapping cowbirds can significantly reduce brood parasitism², and is a standard management tool in one California study area³.

Conservation measures proposed Protect key habitats for the species and manage others in a beneficial way. Continue to monitor trends and ascertain whether it is still declining. Identify the key threats and develop appropriate actions to tackle them.

References 1. Brown (1993). 2. Collins et al. (1991). 3. Beezley and Rieger (1987). 4. J. Wells and K. Rosenberg in litt. (2003).

Text account compilers Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Matt Harding (BirdLife International)

Contributors Greg Butcher (National Audubon Society), Ken Rosenberg (Cornell Laboratory of Ornithology), Jeff Wells (Partners in Flight)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Greg Butcher (National Audubon Society)

Recommended citation BirdLife International (2009) Species factsheet: Vireo bellii. Downloaded from http://www.birdlife.org on 9/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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