The harpy eagle is legendary, although few people have seen one in the wild. Early South American explorers named these great birds after harpies, the predatory “frightful, flying creatures with hooked beak and claws” of Greek mythology. This dark gray bird of prey has a very distinctive look, with feathers atop its head that fan into a bold crest when the bird feels threatened. Some smaller gray feathers create a facial disk that may focus sound waves to improve the bird’s hearing, similar to owls.