Size: L: 70 cm. Wt: Males: 2700-3300 g. Females: 2500-2800 g. Males and females similar; males heavier. Two colour phases exist; white and blue. Intermediates occur frequently and combine characteristics of both phases.

White Phase Adult: head, neck,and body white, with black wingtips; bill and legs pinkish

Blue Phase Adult: head and upper neck white; lower neck and body dark greyish-brown, with variable amounts of white on underparts; bill and legs pinkish

White Phase Juvenile: head and underparts whitish to pale grey; upperparts pale grey, with black wing tips; bill and legs dark grey

Blue Phase Juvenile: head and neck dark greyish-brown; body and underparts grey-brown, paler than head and neck; bill and legs dark grey