Bell’s Vireo

Vireo bellii
Range Map

Bell’s Vireos are migratory and breed in the central and southwestern United States and northern Mexico. They spend winters in central and southern Mexico and Baja California. Habitat loss threatens this species across its range. In 1986, when there were only about 300 nesting pairs in existence, federal and California state agencies listed Least Bell’s Vireo as endangered, and instituted protective measures. Since then, their numbers have been slowly increasing.

Science recognises four subspecies of Bell’s Vireo:

  • V. b. pusillus (Least Bells Vireo) breeds on the Pacific Slope of California from Santa Barbara to northern Baja California, and spends winters near the southern tip of the Baja California peninsula.
  • V. b. arizonae breeds in Nevada, Utah, Arizona and southwest and northwestern New Mexico, and spends winters in western Mexico.
  • V. b. medius breeds in southeast New Mexico and west Texas and spends winters in central Mexico.
  • V. b. bellii breeds in the midwestern USA and spends winters on the Pacific Slope from Mexico to Nicaragua.

I remember meeting the Least Bell’s Vireo for the first time on the desert slopes of east San Diego County. It was the curious bubbling song that caught my attention. The rapid-fire delivery of too many notes for the allotted time was too much for me to resist, and I braved the thick brush and rough trail to learn of its author. When I finally spotted the songster, I realized I’d met its Arizona cousin a few years earlier, north of Tucson Either the songs of these two birds were different enough, or my memory of the Arizona bird’s song too hazy for me to recall, but as I listened to this San Diego bird’s barrage of notes, I failed to identify by sound alone.

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