The hoatzin (/hoʊˈætsɪn/ hoh-AT-sin) or hoactzin (/hoʊˈæktsɪn/ hoh-AKT-sin; Opisthocomus hoazin), is the only species in the order Opisthocomiformes. It is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and the Orinoco basins in South America. It is notable for having chicks that have claws on two of their wing digits.
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| Credit : Wikipedia |
It is the only member of the genus Opisthocomus (Ancient Greek: "long hair behind", referring to its large crest). This is the only extant genus in the family Opisthocomidae. The taxonomic position of this family has been greatly debated by specialists, and is still far from clear.
The hoatzin is pheasant-sized, with a total length of 65 centimetres (26 in), and a long neck and small head. It has an unfeathered blue face with maroon eyes, and its head is topped by a spiky, rufous crest. The long, sooty-brown tail is a broadly tipped buff. The upper parts 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. The hoatzin is a herbivore, eating leaves and fruit, and has an unusual digestive system with an enlarged crop used for fermentation of vegetable matter, in a manner broadly analogous to the digestive system of mammalian ruminants. The alternative name of "stinkbird" is derived from the bird's foul odour, which is caused by the fermentation of food in its digestive system.
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| Credit : Wikipedia |
The hoatzin was originally described in 1776 by German zoologist Statius Müller. There has been much debate about the hoatzin's relationships with other birds. Because of its distinctness it has been given its own family, the Opisthocomidae, and its own suborder, the Opisthocomi. At various times, it has been allied with such taxa as the tinamous, the Galliformes (gamebirds), the rails, the bustards, seriemas, sandgrouse, doves, turacos and other Cuculiformes, and mousebirds. A whole genome sequencing study published in 2014 places the hoatzin as the sister taxon of a clade composed of Gruiformes (cranes) and Charadriiformes (plovers).
The hoatzin is a folivore - it eats the leaves (and to a lesser degree fruits and flowers) of the plants that grow in the marshy and riverine habitats where it lives. It clambers around clumsily along the branches, and being quite tame (though they become stressed by frequent visits), often allows close approach and is reluctant to flush. The hoatzin uses a leathery bump on the bottom of its crop to help balance itself on the branches. Once it was thought that the species could eat the leaves of only arums and mangroves, but the species is now known to consume the leaves of more than fifty species. One study undertaken in Venezuela found that the hoatzin's diet was 82% leaves, 10% flowers, and 8% fruit. Any feeding of insects or other animal matter is purely accidental.