Hoatzin (Opisthocomus hoazin)

BirdAmazonFolivore

Overview

The hoatzin (Opisthocomus hoazin) is one of the most peculiar birds in the world — a turkey-sized, spiky-crested bird of South American swamps and riverbanks, with a small blue face, red eyes, and a ragged crest. It is so unusual that it is placed in its own family, and its exact relationships to other birds have long puzzled scientists.

Its strangest feature is its digestion: the hoatzin is the only bird known to ferment its food in an enlarged foregut, the way cattle and other ruminants do — which is also why it has earned the nickname “stinkbird.”

Note: the hoatzin's evolutionary placement is still debated; treat statements about its relationships as ongoing science and verify against authoritative sources.

Habitat & Range

Hoatzins live in the swamps, flooded forests, and riverside and lakeside vegetation of the Amazon and Orinoco basins in tropical South America. They keep to dense waterside thickets, clambering through branches over the water rather than ranging widely, and they are usually found in noisy social groups.

Diet

The hoatzin is a folivore — a rare diet among birds — feeding mainly on leaves, along with some flowers and fruit. To handle this tough, low-energy food, it ferments the plant material with the help of microbes in a greatly enlarged crop and lower oesophagus, breaking down cellulose much as a cow's stomach does. This foregut fermentation is unique among birds.

Behavior

Because so much of the hoatzin's body is given over to its fermentation chamber, it is a clumsy, weak flier that mostly clambers about in waterside vegetation. The fermentation also gives the bird a distinctive manure-like smell, hence “stinkbird.” Most remarkably, hoatzin chicks have two functional claws on each wing, which they use to clamber through branches and to climb back up after dropping into the water to escape predators — the claws are lost as they mature. Hoatzins are social and very vocal.

Human Interaction & Conservation

The hoatzin is widespread in suitable habitat and is generally not considered threatened, helped by its unpleasant smell and stringy flesh making it a poor target for hunting. It is a favourite of Amazon wildlife tours and a scientific curiosity. As with much Amazonian life, large-scale habitat change is the broad long-term concern. Consult authoritative sources for current status.

More photos of the hoatzin