Identification: Breeding plumage in male; black cap, wings and tail. Underparts lemon-yellow. Two striking white wing bars present. Upperparts generally black but flecked with some yellow. Female plumage lacks black cap and upperparts of breeding male and is instead yellowish green in these areas, underparts lemon-yellow, wings black with white edging to feathers. Non-breeding males are similar to females apart from more black on wings and retaining the black on uppertail coverts and tail.