The red-eyed vireo (Vireo olivaceus) is a small American songbird. It is somewhat warbler-like but not closely related to the New World warblers (Parulidae). Common across its vast range, this species is not considered threatened by the IUCN. Adults are mainly olive-green on the upper parts with white underparts; they have a red iris and a grey crown edged with black. There is a dark blackish line through the eyes and a wide white stripe just above that line. They have thick blue-grey legs and a stout bill. They are yellowish on the flanks and undertail coverts (though this is faint in some populations[which?]). Red-eyed vireos are one of the most prolific singers in the bird world. They usually sing high up in trees for long periods of time in a question-and-answer rhythm. This species holds the record for most songs given in a single day among bird species, with more than 20,000 songs in one day. (Source: Wikipedia.org, CC BY-SA)