Young hoatzins are born with functional claws on their wings, which they use to climb through branches—an unusual trait that resembles ancient feathered dinosaurs like Archaeopteryx.
The hoatzin is the only bird known to digest its food via foregut fermentation, similar to cows. Its enlarged crop acts like a rumen, where bacteria break down tough plant material.
This unique digestive process causes the bird to emit a strong, manure-like odor, earning it the nickname "stinkbird."
Hoatzins live in swampy, riverine forests of the Amazon and Orinoco basins in South America, often nesting near water.
Genetic studies have struggled to place the hoatzin within the bird family tree. Its evolutionary lineage is so distinct it’s often referred to as an "evolutionary orphan."
Adult hoatzins have a scruffy crest, bright blue skin around their red eyes, and long, ragged-looking feathers that give them a prehistoric look.
Despite being birds, hoatzins are clumsy fliers. Their large crop takes up so much space it restricts chest movement, making flight inefficient.