Hoatzin

Overview

The hoatzin ( WAHT-sin, -⁠seen; also HO-tsin and hoh-AT-sin) (Opisthocomus hoazin) is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and Orinoco Basins in South America. It is the only extant species in the genus Opisthocomus which is the only extant genus in the family Opisthocomidae under the order Opisthocomiformes. Despite being the subject of intense debate by specialists, the taxonomic position of this family is still far from clear.
The hoatzin is notable for its chicks having primitive claws on two of their wing digits. It is unique among birds in possessing a digestive system that significantly supports the fermentation and the effective breakdown of plant matter, a trait more commonly known from herbivorous ungulate-ruminant mammals and some primates.

Summary from Wikipedia, available under CC BY-SA 4.0.

Diet: Leaves, fermented in an enlarged crop, which gives the bird a strong smell.