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The hoatzin (Opisthocomus hoazin) is a tropical bird found in the Amazon basin and the Orinoco Basin in South America. It is the only extant species in the family Opisthocomidae. A folivore, the hoatzin eats the leaves of the plants that grow in its marshy and riverine habitat. Its digestive system supports fermentation and effective breakdown of plant matter, a trait typically found in ruminants such as cattle. Because of aromatic compounds in the leaves it consumes and the fermentation required to digest them, the hoatzin has a manure-like odor, giving it a local nickname of stinkbird. It is a noisy bird and makes a variety of hoarse calls, including groans, croaks, hisses and grunts. Its chicks feature primitive claws on two of their wing digits, which they use immediately after hatching to move around tree branches. The hoatzin is believed to remain fairly common in a large part of its range, but its population is likely decreasing due to habitat loss. It is the national bird of Guyana. This hoatzin was photographed on a branch above the Napo River, a tributary of the Amazon River, in northeastern Ecuador.Photograph credit: Charles J. Sharp