Strange Birds: Hoatzins

The hoatzin is one of the world’s strangest bird species – its chicks possess claws on the leading edge of their wings!

Hoatzins live in South American tropical rain forests. These chicken-sized birds spend their time clambering through the trees that hang over slow-moving rivers.

The hoatzin chicks use the nearby water as an escape route. When faced with danger, the chicks readily drop down into the water. They are adept at swimming and diving. When danger passes, they are able to climb back up out of the water, using the primitive claws on their wings.

These claws drop off as the hoatzin chick grows up. But hoatzins continue to be strange, as adults. They have an unusual appearance, with a long neck, tiny head, ragged crest, and featherless face. They only eat leaves- an unusual diet among birds, since leaves are not easily digested. One quarter of the hoatzin’s weight consists of its oversized stomach, needed to digest the leaves. This extra weight makes hoatzins poor fliers.

The hoatzin’s baby-claws make it superficially similar to the prehistoric bird-dinosaur Archeopteryx. Archeopteryx, which also had wing-claws, is known only from fossils, and is considered to be a possible evolutionary link between birds and dinosaurs. But the hoatzin is not directly related, and evolved its strange wing-claws separately.