Gobemoucheron du Yucatan Polioptila albiventris

Tiny gray and white bird with cocked tail. Local in dry tropical scrub of northern Yucatan Peninsula. Male has a black cap, solid in breeding season, but with narrow white eyebrow in non-breeding season. Female has gray cap with narrow white eyebrow year-round. Told from Blue-gray Gnatcatcher by face pattern: Blue-gray has a white eyering, not a white brow.