The Hoatzin is the last remaining member of an ancient bird lineage that branched off independently 64 million years ago, right after the mass extinction event that wiped out the dinosaurs.
Found in the Amazon and Orinoco regions of South America, the Hoatzin (Opisthocomus hoazin) is regarded as one of the most mysterious birds in the world.
The Hoatzin features a long neck and a small head, with a bare blue face and chestnut-colored eyes, topped with a tuft of feathery crest on its head.
The upper body of the Hoatzin is dark gray, while the underside is lighter. The outer wing feathers are brown, and its long gray tail has a white tip.
Juvenile Hoatzins possess two claws on each wing. Right after hatching, they can use these claws and their feet to crawl around tree branches.
When predators like large black hawks attack their nesting area, adult Hoatzins will fly noisily around to distract the predator, while the juveniles leave the nest and hide in the bushes.
They can swim underwater to escape danger, then use their clawed wings to climb back to safety in the nest.
The claws on the wings of juvenile Hoatzins bear a striking resemblance to the Archaeopteryx, an ancient bird known only from fossils.
However, there is also a hypothesis suggesting that the claws of the Hoatzin are of more recent origin and may have evolved from the need to frequently leave the nest and climb through dense vines and trees.
In 2015, a genetic study indicated that the Hoatzin is the last remaining member of an ancient bird lineage that branched off independently 64 million years ago, right after the dinosaur extinction event.
They are classified in the Opisthocomiformes order, with their closest relatives possibly being the Galliformes or Cuculiformes orders.
Hoatzins live in groups and nest in small colonies. Their diet primarily consists of leaves, and they occasionally consume flowers and fruits.
The digestive system of the Hoatzin is unique among birds. They harbor special bacteria in the front part of their intestines to break down and ferment the plant material they consume, similar to ruminants.
They typically lay two or three eggs in a stick nest built above the water.
As a noisy bird, the Hoatzin produces various types of hoarse calls, including moans, grunts, hisses, and complaints.
Currently, Hoatzins are at risk of decline due to habitat loss, primarily caused by deforestation in the Amazon.
