Large, dark, olive-green sunbird with a long, down-curved bill. Can show yellow tufts on the shoulders, though these are usually hidden. Found in forest and adjacent gardens and lush scrub. Usually in the understory. Less social than other sunbirds, and often seen alone. Most distinctive vocalization is a pretty, up-and-down series of clear notes. Mouse-colored Sunbird is similar, but Olive Sunbird is more olive-green than gray.