Size: L: 65 cm. Wt: Males: 1550 g. Females: 1250 g. Males and females similar, but males somewhat heavier. This species not seasonally dimorphic.

Adult: head, neck, and breast black; bill stubby, black; whitish patch on side of neck; belly mottled light brown; back blackish-brown; upper tail coverts white; tail feathers black; legs black.

Juvenile: similar to adult, but with whitish wing coverts, paler secondaries, and fainter neck patches.