The Gray-bellied Hawk is a large and powerful, poorly-known Accipiter of South American rainforests. It is very dark gray above and pale gray below, with a tail that is barred black and dark gray. The adult superficially resembles the Slaty-backed Forest-Falcon (Micrastur mirandollei), but is larger with a relatively shorter tail, less-pronounced facial skin, and darker gray bars on the tail; the plumage pattern of the immature is strikingly similar to that of the Ornate Hawk-Eagle (Spizaetus ornatus). This species occurs in forest from northern Colombia and Venezuela south through the Amazon basin, as well as in the forests of southeastern Brazil south to northern Argentina and Paraguay. It apparently occurs at very low densities, as records are few in most areas and its precise distribution and movements are unclear. Southern populations may be migratory. The diet, feeding behavior, nest, and breeding behavior of this species are unknown.