Hutton's vireo (Vireo huttoni) is a small songbird. It is approximately 5 inches (12–13 cm) in length, dull olive-gray above and below. It has a faint white eye ring and faint white wing bars. It closely resembles a ruby-crowned kinglet, but has a thicker bill and is slightly larger in size. Its most common song is a repeated chu-wee, or a chew, but will have other variations. Its call is a mewing chatter. Birds are mostly resident in year round, but there may be some altitudinal and short distance migration. Hutton's vireo may join a mixed species flock for the winter.