Hoatzin | Opisthocomiformes

Hoatzinachtigen | Hoatzines | Hoatzin

An order with only a single living species, the Hoatzin, a pheasant-sized bird with a small head on a long neck, a ragged upright crest, bare blue skin around the red eye and a long, broad tail. It is the only bird that feeds almost entirely on leaves and, like a ruminant, ferments them with the help of bacteria, in a greatly enlarged crop rather than in the stomach. To make room for the crop the front of the breastbone is reduced, leaving the flight muscles weak; the Hoatzin flies poorly and heavily and mostly clambers clumsily through the vegetation. The fermentation gives the bird a musky smell, which has earned it nicknames such as stinkbird in English and Spanish. The chicks have two well-developed claws on each wing with which they climb through the branches, and when threatened they drop from the nest into the water, swim and dive away and later climb back up. Breeding is in groups, often with helpers from earlier broods, in an untidy stick nest over water. Its relationship to other birds remains uncertain; it is an old, isolated lineage, with fossil relatives also found in Africa and Europe. In this guide the Hoatzin lives in the Amazonian lowlands east of the Andes, in Colombia, Ecuador, Peru and Bolivia, along slow rivers and oxbow lakes with overhanging vegetation.