Adult length: 17-19 inches (43-48 cm); adult weight: 17.7-28.9 ounces (502-820 g); appearance & coloration: long grey bill, long head and longish legs. It has a white face and crown, and black rear head. The back and wings are dark brown to black, and the underparts are black, although the flanks have fine white barring. The neck is chestnut. All plumages are similar, except that juveniles have a much less contrasted head pattern.