The thirteen vireo species that migrate to the United States represent a small subset of a family of some fifty species in four genera that primarily stay close to their homes in South America, Central America and Mexico. Physically their small size and somewhat dull gray, olive and brown feathers makes them difficult to identify. Binocular birders who only can see them from a distance can easy to mistake them for kinglets or the empid flycatchers.
Good news, seasoned birders known some physical and behavioral quirks of the birds that help with identification issues. Generally speaking, a triangular head characterized the generic Empid Flycatcher. Vireos have a well rounded head. Quick reflection also reminds us that the name flycatcher often matches their behavior. Many species tend to sit on branches, keeping an eye out for nearby insects and then fly out to catch them. Many of the vireos prefer to remain hidden in the thickets.
Finally, a few of the species such as the Black-capped, Blue Headed, White Eye and Yellow-throated have sufficiently strong physical differences to make identification easy from a distance. A close up view of the Red-eyed Vireo, as shown at the picture at the top of the page, would make identification a snap. Another helpful identification clue is that vireos take their singing seriously. If it sings and sings and sings, it’s probably a vireo. Patience is required for any photographer waiting for one to sit on an open branch.
Vireo populations across the United States tend to be regionally situated with the East and Southeast seeing six of the species.
Philadelphia Vireos mostly breed in Canadian forests. However, they migrate through most areas of the Eastern half of the country. The yellow feathers on the belly and a white eye stripe are pretty good field identification clues.
Red-eyed vireos breed in most forested areas east of the Rocky Mountains. The darker cap and endless singing are sufficient field identification clues without seeing the distinctive red eyes.
Blue-headed Vireo breed in the northern half of the Appalachian Mountains and a subset winters along the Southeast Coastal areas. Again, in most instances the blue feathers on the head tend to stand out for a good field identification clue.
White-eyed Vireos are a mainstay of the family. They breed in most areas of the East and a small population winters along the Southeast Coast. The yellow feathers around the eye help identify it.
The picture shows that the Yellow-throated Vireo has more than a yellow throat. The entire head is covered by yellow feathers. Count it among the most common of the Eastern breeding Vireos, although it does not winter along the coastal Southeast.
Warbling Vireos have the widest range of all the species. With the exception of the southern areas of the United States, they can be found in forest areas from Coast to Coast.
Cassin’s Vireos are West Coast forest breeding birds. Their head feathers are slightly blue and they were previously grouped with the Eastern species, the Blue-headed Vireo.
Depending on how the West is identifies four or five different vireo species can be found during spring. Hutton’s Vireo is truly a West Coast bird that inhabits forest areas along the entire coast. They can easily be confused with Kinglets although they do not move at a constant speed like the Kinglets.
The Southwest Deserts host two similar looking Vireos, the Gray Vireo and the Plumbeous Vireo. Gray vireos tend to migrate to lower elevation areas. While they have distinct white circles around the eyes, they lack the white lines from the eyes to the beak, often referred to as spectacles of the Plumbeous Vireo.
Plumbeous vireos have rich gray feathers that stay a fairly consistent color from the head to the back. Their breeding range extend as far north as Utah and Colorado.
Bell’s Vireo also breed in the southern most areas of the Southwest. However, they tend to stay away from the desert and mountain areas and focus their breeding behavior in more open shrub land and forests through the Midwest.
Black-capped Vireos have a small migration presence that reaches into a few areas of Texas and Oklahoma. Black-whiskered Vireos breed only in South Florida.