Hoatzin

## Description

The Hoatzin is a tropical bird native to South America. It is notable for having chicks that have claws on two of their wing digits. The hoatzin has an unfeathered blue face with maroon eyes, and its head is topped by a spiky, rufous crest. The long, sooty-brown tail is broadly tipped buff. The upperparts are dark, sooty-brown-edged buff on the wing coverts, and streaked buff on the mantle and nape. The under parts are buff, while the crissum (the undertail coverts surrounding the cloaca), primaries, underwing coverts, and flanks are rich rufous-chestnut, but this is mainly visible when it opens its wings.

## Distribution

Hoatzins are found in the Amazon and the Orinoco basins in South America. These birds live in riparian forests, swamps, and mangroves.

## Behavior

Hoatzins are non-migratory gregarious birds. They live in family groups or small flocks. They are active during the day and usually forage in the early morning and early evening spending the rest of their time roosting. When feeding they clamber around clumsily among the branches, and are quite tame (though they become stressed by frequent visits). Hoatzins are poor fliers; they only soar from tree to tree and need a lot of noisy efforts to move away when alarmed. These are quite vocal birds that communicate with a variety of hoarse calls, including groans, croaks, hisses, and grunts. Their calls are often associated with body movements, such as wing spreading.

## Diet

Hoatzins are herbivores (folivores). They eat the leaves of the plants that grow in the marshy and riverine habitats where they live. They may also occasionally feed on fruits and flowers.

## Reproduction

Hoatzins are monogamous which means that males will mate with only one female and females will mate with only one male. They breed during the rainy season and nest in small colonies. Females lay 2 or 3 eggs in a stick nest in a tree hanging over water in seasonally flooded forests. The eggs are incubated around 32 days by both parents. The chicks usually remain in the nest for 2 or 3 weeks after hatching and are fed by both parents for up to 2 months. The begin tp fly at 55-65 days and reach reproductive maturity when they are 1 year old.

## Population

### Population threats

Hoatzins remain fairly common in a large part of their range and are not considered endangered. However, these birds suffer from habitat loss and in some regions, their preferred habitats, mangrove, and riverine forest are disappearing quickly. In Brazil, indigenous peoples sometimes collect their eggs for food, and the adult birds are occasionally hunted.

### Population number

The IUCN Red List and other sources don’t provide the number of the hoatzin population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.

## Fun Facts

The hoatzin is the only member in its genus Opisthocomus; the word 'opisthocomus' comes from Ancient Greek and means 'wearing long hair behind' which refers to the bird's large crest.

In 2015, genetic research indicated that the hoatzin is the last surviving member of a bird line that branched off in its own direction 64 million years ago, shortly after the extinction event that killed the non-avian dinosaurs.

Hoatzins have an unusual digestive system with an enlarged crop used for fermentation of vegetable matter, just like in cattle. These striking birds are sometimes called "stinkbirds" due to their foul odor, which is caused by the fermentation of food in their digestive system.

In order to help balance itself on the branches, the hoatzin uses a leathery bump on the bottom of its crop.

Hoatzins enjoy sunbathing; they often perch in trees with spread wings and erected back feathers to warm them under the sun.

The hoatzin chicks have an odd feature; they have two claws on each wing. Immediately on hatching, they can use these claws, and their oversized feet, to scramble around the tree branches without falling into the water. When predators such as the Great black hawk attack a hoatzin nesting colony, the adults fly noisily about, trying to divert the predator's attention, while the chicks move away from the nest and hide among the thickets. If discovered, however, they drop into the water and swim under the surface to escape, then later use their clawed wings to climb back to the safety of the nest.

The hoatzin is the national bird of Guyana.