Look for Red-eyed Vireos high in the canopy of deciduous and mixed forests, woodlands, parks, and large gardens. They are adaptable and can be found in various forested habitats, from mature forests to regenerating clearcuts.

The most reliable way to locate a Red-eyed Vireo is by its distinctive, monotonous, yet varied song, often described as a series of short, questioning phrases ('Here I am, where are you?'). They move deliberately and slowly through the foliage, gleaning insects, making them difficult to spot despite their song. Look for a vireo-sized bird with a gray cap, olive-green back, white belly, and a prominent white eyebrow stripe bordered by a dark line above and a faint dark line through the eye. The red eye is a key field mark but often difficult to see.

These birds are most vocal and active during the morning hours, especially during the breeding season (late spring through summer). During spring and fall migration, they can be found in a wider variety of habitats as they pass through, and observation can occur throughout the day.