diagnostics
76-97 cm, 2.2-6.0 kg. Sexes dimorphic in plumage colouration, and male considerably larger. Head dark brown with paler flecking on supercilium and lores; crown may have indistinct whitish median stripe. Hind-neck and upper mantle orange with white nape. Upperparts mottled brown and buff with darker brown vermiculations. Tail broadly barred dark brown and creamy white. Upperwing coverts mottled brown. Primary coverts largely white with flight feathers blackish brown with white patches on inner primaries. Foreneck and upper breast brown. Remainder of underparts including flanks and undertail white. Bill horn. Eyes brown. Legs greenish or greyish brown. Female differs in having a more heavily speckled, paler head and foreneck; upperparts of females are more heavily mottled (Allan 2005).
