Hoatzinidae
Hoatzinidae is a family of birds comprising a single living species, the hoatzin (Opisthocomus hoazin), found in the Amazon and Congo rainforests. This pheasant-sized bird is unique for several reasons, most notably its unusual digestive system. Hoatzins are folivores, meaning they primarily eat leaves. Their digestive process involves bacterial fermentation in a large crop, similar to that of ruminant mammals. This fermentation allows them to break down the cellulose in leaves, but it also produces a strong, musky odor, earning them the nickname "stinkbird." This odor is thought to deter predators.
Another remarkable feature of the hoatzin is its juvenile stage. Hoatzin chicks possess claws on their wings,