Hoatzins are a peculiar species of bird indigenous to the Amazon and other regions of South America. Clumsy by nature and sporting a unique set of claws as fledglings, hoatzins are also recognized for their odor, comparable to manure. Why the smell? “Stinkbirds,” as they are affectionately referred to as, feed on leaves, necessitating the need for a foregut fermentation system. The hoatzin’s gullet and crop contain a bacteria specialized in breaking down this plant matter before reaching the stomach. As a result, the fermenting leaves create the stench.