The thick-billed vireo (Vireo crassirostris) is a small songbird. It breeds in the West Indies in the Bahamas, Turks and Caicos Islands, Cayman Islands, Tortuga Island in Haiti and on cays off the coast of Cuba. It occasionally can be found as a vagrant to south Florida in the United States. The subspecies V. c. approximans of Providencia Island is sometimes treated as a subspecies of the mangrove vireo (V. pallens) or as a separate species, the Providencia vireo. Its head and back are a greyish olive, and the underparts are buffy white. The wings and tail are dark, and there are two white wing bars on each wing. The eyes have dark irises. Sexes are similar. It shows a yellow partial spectacle just above the bill.