About Opisthocomus hoazin (Statius Muller, 1776)
The hoatzin, Opisthocomus hoazin, is pheasant-sized, with a total length of 65 cm (26 in). It has a long neck, a small head, an unfeathered blue face, and maroon eyes, with a spiky rufous crest on top of its head. Its long sooty-brown tail is bronze-green, ending in a broad whitish or buff band. The bird’s upper body is dark: wing coverts have dark sooty-brown edges with buff coloring, while the mantle and nape are streaked with buff. Its underparts are buff. The crissum (the undertail coverts surrounding the cloaca), primary flight feathers, underwing coverts, and flanks are a rich rufous-chestnut, though this coloring is mostly only visible when the hoatzin opens its wings. This is a noisy bird that produces a range of different hoarse calls, including groans, croaks, hisses, and grunts. These calls are often paired with body movements, such as spreading the wings.
