Tiny, hyperactive songbird with an uneven white eyering. Plain olive overall, with slightly brighter greenish edges on the wing and tail feathers. The namesake ruby crown is only present on males, and usually concealed. When agitated, it can be flared up into a bright expressive crest. Breeds in coniferous forests. In migration and winter, found in basically any wooded habitat, including deciduous forests, shrubby woodland, and field edges. Often forages quite low to the ground, sometimes joining mixed flocks of other songbirds. Energetic, moving quickly and flicking its wings. Listen for short, harsh call notes, usually doubled, and surprisingly loud song for such a small bird. Compare with Hutton’s Vireo, which is similar in plumage but has a thicker bill and forages more sluggishly.