Warbling Vireo

Vireo gilvus
Range Map

The Warbling Vireo occupies a variety of deciduous forest habitats, predominantly riparian from Alaska to Mexico and the Florida Panhandle. In winter, these birds migrate to southern Mexico and Central America.

During my visit to south Texas in 2021, I met both Warbling and the Philadelphia Vireos. Differentiating a Warbling Vireo from a Philadelphia Vireo is a tricky proposition. There are no recognized subspecies for the Philadelphia Vireo, yet there is some variation to their look. Some field guides describe “Drab” adults vs. “Bright” adults, with the “Bright” birds having more of a yellow wash than the “Drab” individuals. Adding to the confusion, we divide Warbling Vireos into an “Eastern” and “Western” clan and the Eastern group has a “Drab” and a “Bright” contingent.

Studies and interpretations of data have suggested different conclusions over the years, as to how to define subspecies for the Warbling Vireo. The most recent study from 1991 classifies five subspecies divided into an Eastern and a Western group:

  • Eastern group
    • V. g. gilvus. These birds breed over much of eastern North America and winter in southern Mexico and Central America.
  • Western group
    • V. g. swainsoni breeds from southeast Alaska, the Yukon and Northwest Territories in Canada and south through Montana and Oregon and along the Pacific Slope into Baja California (Mexico). They spend winters in Mexico.
    • V. g. victoriae breeds in Baja California, but we are uncertain where they spent winters.
    • V. g. brewsteri breeds in the Rocky Mountains and south through Texas and central Mexico.
    • V. g. sympatricus is resident in the mountains near Puebla (Mexico).

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