Small songbird nearly identical in plumage to Red-eyed Vireo but slightly duller and browner. Drab olive-greenish above and white below with gray cap, white eyebrow, and brown eye. Telltale black whisker mark often difficult to see, but is diagnostic. Hooked bill is rather long for a vireo. Primarily a Caribbean species with limited range in U.S.; breeds in scrubby mangrove forests in Florida. Can be difficult to spot in dense foliage, but listen for song: repeated three-parted chirping phrases that are vaguely reminiscent of House Sparrow.