Hoatzin
The hoatzin (Opisthocomus hoazin) is a pheasant-sized bird of the swamps and riverbanks of the Amazon and Orinoco basins. It eats leaves and ferments them in an enlarged crop, which gives it a manure-like smell.
The hoatzin (Opisthocomus hoazin) is a pheasant-sized bird of the swamps and riverbanks of the Amazon and Orinoco basins. It eats leaves and ferments them in an enlarged crop, which gives it a manure-like smell.
🧬 Field Guide Specimen: Open Hoatzin in the CRV Science Field Guide to log the specimen, see its place among the Evolutionary lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.
A Bird That Ferments Like a Cow
Almost all birds digest food in the stomach and gizzard, but the hoatzin has a huge crop packed with bacteria that break down tough leaves, similar to the foregut of a cow. The crop takes up so much room that the flight muscles are reduced and the bird is a poor flier.
Chicks With Claws
Newly hatched chicks have two claws on each wing, with which they climb trees. If a predator comes, they can drop into the water and swim, and then climb back up. The claws are lost with age.
Where Does It Fit?
The hoatzin sits on a lone branch of the bird tree, in an order of its own, and its closest relatives have been debated. Genome analysis has helped place it among the more modern birds. See Evolution.
Hoatzin at a Glance
| Property | Value |
|---|---|
| Scientific name | Opisthocomus hoazin |
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Aves |
| Order | Opisthocomiformes |
| Family | Opisthocomidae |
| Field Guide group | Evolutionary Oddities (Unique & Disputed Lineages) |
| Diagnostic feature (Field Guide) | Reversible functional wing claws in juveniles, enormous muscular crop functioning as a bovine-like foregut fermenter, unfeathered blue facial skin. |
| IUCN Red List status | Least Concern (LC), assessed 2024 |
| Order | Opisthocomiformes |
| Digestion | Foregut fermentation in the crop |