Adult length: 33 – 37 in (83 – 95 cm); adult weight: 8.8 – 9.9 lbs. (4 – 4.5 kg); wingspan: 19.6 – 22.4 in. (498 – 568 mm); appearance & coloration: Sexes similar. Large bodied, with stout tarsi and toes, and a relatively short, “chicken-like” bill. Rear crown has a crest, usually recumbent, of elongated, pointed feathers. Head and upperparts gray. Remiges and rectrices are fuscous. Collar, composed of feathers with a velvety texture, around base of neck black; usually there is a faint white neck ring above the black. Foreneck, breast and sides pale gray, with indistinct white mottling and streaking; belly less marked, almost uniform pale gray or white. Underwing coverts white. Manus has two sharp, spike-like spurs, the more proximal of which is the longer of the two. The iris is brown or orange-brown; the orbital skin is rosy or reddish pink, and the cere is pinkish gray. Bill is a grayish brown, and tarsi are rosy.