Hooded Warbler (Wilsonia citrina) Science Article 7
Dwight (1900:284-285) provided two hypotheses to explain the variable amount of black plumage in female Hooded Warblers (Wilsonia citrina): ‘The adult winter plumage . . . shows a variable amount of black about the head and throat.
EUGENES . MORTON, Wilson Bull., 101(3), 1989, pp. 460-462