Monotypic. Plumage varies, quite fascinating. Breeding (MAR-AUG) and Non-breeding (SEP-MAR). See M/F notes for more details. M/F differ, with breeding male crown/head black, prominent streaking while female is more brown with streaking. Non-breeding difference marginal (mostly shading), but interestingly differs from both breeding as M/F show more yellow. Neat!