Is a Red-eyed Vireo a warbler?

Quick Answer

The Red-eyed Vireo is not actually a warbler, despite sometimes being called the “Red-eyed Warbler.” It is a songbird in the vireo family Vireonidae, not the wood-warbler family Parulidae like true warblers. So while it shares some similarities with warblers, the Red-eyed Vireo is taxonomically distinct and not considered a warbler by ornithologists.

What is a Red-eyed Vireo?

The Red-eyed Vireo (Vireo olivaceus) is a small songbird found throughout much of North America. Some key facts about the Red-eyed Vireo:

• Scientific name: Vireo olivaceus
• Length: 5.5-6 inches
• Weight: 0.4-0.7 ounces
• Coloring: Olive upperparts, white underparts, gray crown and red eyes
• Song: Distinctive, repetitive whistles and phrases
• Range: Breeds across Canada and the eastern/central U.S., winters in South America
• Habitat: Deciduous and mixed forests
• Diet: Insects and berries

The Red-eyed Vireo gets its common name from its most distinctive feature – bright red eyes. It is a plain-looking bird otherwise, with olive upperparts, white underparts and a gray crown. But its song, a repetitive series of whistles and short phrases, is very noticeable.

Red-eyed Vireo Taxonomy

The Red-eyed Vireo belongs to the vireo family Vireonidae, which includes around 50 small songbirds found mostly in North and South America. There are several different classifications of vireos:

• Genus: Vireo
• Species: V. olivaceus
• Subspecies: Includes V. o. olivaceus, V. o. flavoviridis, V. o. keyensis and others

Within the Vireo genus, the Red-eyed Vireo is most closely related to other “solitary” vireos like the Plumbeous Vireo and Cassin’s Vireo. These vireos are monotypic – they do not form mixed flocks with other species.

How do Red-eyed Vireos compare to warblers?

While not actually warblers, Red-eyed Vireos do share some similarities with birds in the wood-warbler family Parulidae:

So while the vireo and warbler families are distinct taxonomically, they do share similarities in size, habitat, behavior and more that can make them seem superficially similar. But experienced birders know how to distinguish vireos from warblers in the field.

Key Identification Differences

While casual birders may lump the Red-eyed Vireo with warblers, there are several key differences that allow experts to confidently distinguish vireos:

Shape and Proportions

Warblers tend to be more elongated and slender than Red-eyed Vireos. Vireos have a larger, rounder head and thicker bill relative to their body size.

Plumage

Warblers display more distinctive plumage patterns, streaks, wingbars and bright colors than Red-eyed Vireos. The vireo’s subdued olive upperparts and plain underparts give it a more nondescript look.

Behavior

Vireos tend to deliberately pick insects from foliage, unlike warblers which are more erratic fliers. Warblers also flick their wings and tails frequently, while vireos rarely do.

Song

The vireo’s repetitive whistling song, sometimes described as “question & answer”, is very different from typical warbler songs. Warblers sing more complex, variable melodies.

Warbler Species Comparison

The Red-eyed Vireo is most likely to be confused with similarly plain-colored warblers that lack bright yellows, oranges or other colors. A few examples:

Nashville Warbler

• Bold white eye ring
• Smaller size, 4.5 inches
• Thinner bill
• Gray, not red eyes
• Brights yellow wash on underparts

Tennessee Warbler

• All olive-green plumage
• Significant wingbars
• Very thin pointed bill
• No contrasting head like vireo’s gray crown

Orange-crowned Warbler

• More slender, especially pointed bill
• No red eyes
• Faint orange crown patch sometimes visible
• Yellow-tinted underparts

Conclusion

While sharing some superficial similarities with warblers, the Red-eyed Vireo differs taxonomically, behaviorally, and morphologically from true wood-warblers. Ornithologists unambiguously categorize it as a vireo based on key traits like anatomy, vocalizations, proportions and more. Casual birders may mix them up, but expert birders are easily able to distinguish vireos from warblers in the field. So the answer remains: the Red-eyed Vireo, despite sometimes being called a “Red-eyed Warbler”, is definitively not a warbler at all.