The hoatzin (Opisthocomus hoazin), also known as the stinkbird, or Canje pheasant, is a species of tropical bird found in swamps, riparian forest and mangrove of the Amazon and the Orinoco Delta in South America. It is notable for having chicks that possess claws on two of their wing digits.
It is the only member of the genus Opisthocomus (Ancient Greek: “wearing long hair behind”, referring to its large crest[clarification needed]), which in turn is the only extant genus in the family Opisthocomidae. The taxonomic position of this family has been greatly debated, and is still far from clear.
At Lake Sandoval, Peru
The hoatzin is pheasant-sized, with a total length of 65 centimetres (26 in), with a long neck and small head. It has an unfeathered blue face with maroon eyes, and its head is topped by a spiky, rufous crest. The long, sooty-brown tail is broadly tipped buff. The upperparts are dark, sooty-brown-edged buff on the wing coverts, and streaked buff on the mantle and nape. The under parts are buff, while the crissum, primaries, underwing coverts and flanks are rich rufous-chestnut, but this is mainly visible when it opens its wings. The alternative name of “stinkbird” is derived from the bird’s manure-like odour, caused by its digestive system. The hoatzin is a herbivore, eating leaves and fruit, and has an unusual digestive system with an enlarged crop used for fermentation of vegetable matter, in a manner broadly analogous to the digestive system of mammalian ruminants.
This is a noisy species, with a variety of hoarse calls, including groans, croaks, hisses and grunts. These calls are often associated with body movements, such as wing spreading. Calls are used to maintain contact between individuals in groups, warn of threats and intruders and by chicks begging for food.