Hoatzin

The Hoatzin (Opisthocomus hoazin) is a tropical bird found in swamps, riparian forests, and mangroves of the Amazon and Orinoco basins in South America. It is notable for being the only member of the family Opisthocomidae and the order Opisthocomiformes, suggesting a unique evolutionary history.

The Hoatzin is a pheasant-sized bird with a long neck, small head, and a distinctive crest of spiky feathers. Adults have a maroon-brown upperparts and buff underparts. The face is blue with red eyes. Juveniles possess claws on their wings, a feature they use to climb trees. These claws are typically lost in adulthood.

A herbivorous species, the Hoatzin has a highly specialized digestive system adapted for fermenting plant material, particularly leaves and buds. This fermentation occurs in a large crop, similar to that found in ruminant mammals. This process results in a unique, manure-like odor, leading to nicknames such as "stinkbird" or "reptile bird."

Hoatzins are social birds, often found in small colonies. They build nests of sticks in trees over water. They are relatively weak fliers, preferring to clamber through vegetation.