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hoatzin

hoatzin (wätsēn´) [Aztec], common name for a peculiar marsh bird, Opisthocomus hoatzin. The hoatzin is a slender bird with a brownish plumage spotted with white above and reddish-yellow to rust below. It may reach up to 25 in. (64 cm) in length, but weighs no more than 13/4 lb (810 grams). It has a long tail of 10 loosely bound feathers, and a large, bristly crest mounted on a tiny skull. Its young are good swimmers and are peculiar in having claws on their first and second wing digits, which they use along with their short curved bills and weak toes for climbing trees. In this respect the hoatzin is reminiscent of the extinct lizard-bird Archaeopteryx. As the young mature and begin to fly (though never especially well), the claws dwindle. Hoatzins are sometimes called reptile-birds because of their crocodilian odor and harsh, monotonous call. In yet another respect, they are the most advanced of avians. In other birds, food is broken up in the gizzard, but the hoatzin accomplishes this in its well-developed, muscular, horny-walled crop, and its gizzard is much reduced. The hoatzin's specialized diet consists of certain marsh plants, including the mangrove, and the bird is thus restricted to the riverine forests centering around the Amazon Basin where it lives in small colonies of 10 to 50 birds. Both sexes participate in the building of loosely entwined stick nests, 5 to 20 ft (1.5–6.1 m) over the water, in the forks of riverbank trees. The female lays two to four small eggs per clutch, which are yellowish in color with pink or brown spots. Little is known of the incubation period or of parental responsibilities. Hoatzins are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Galliformes, family Opisthocomidae.

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Opisthocomidae

Opisthocomidae (hoatzin; class Aves, order Galliformes) A monospecific family (Opisthocomus hoatzin) which is a dark brown, rufous, and buff bird with a stout, short bill, a small head with long crest feathers, a long neck, and a long tail. It is a weak flier, normally clambering through trees. Its young possess claws on their wings and climb well. The hoatzin is arboreal, inhabiting forests, feeds on fruit and leaves, and nests in trees. It is confined to northern S. America.

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hoatzin

hoatzin See OPISTHOCOMIDAE.

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Hoatzin

Hoatzin

The hoatzin (Opisthocomus hoazin) is one of the worlds most peculiar bird species. It is the sole member of its family, Opisthocomidae. It is peculiar enough to have defied taxonomists best efforts for years.

This bird lives only in the rainforests of northern South America. Its feathers are dark brown on the back and lighter below, and chestnut-colored on its sides. The skin around its red eyes is a startling electric blue. Its head is topped by a crest of long chestnut-colored feathers.

The hoatzin builds its next of sticks in trees or large bushes, usually on boughs that overhang the water. Into this nest the female lays two or three (though sometimes as many as five) buff-colored eggs speckled with blue or brown. After an incubation period of 28 days, out of these eggs hatch some of most remarkable chicks in the order Aves.

Hoatzin chicks are naked, and proof of the old aphorism a face only a mother could love. But beauty does not count: what does count is the tiny claws on the chicks wings. The claws help the chick to hold on as it moves through the branches. But even if it should tumble off the branch and fall into the water below, the hoatzin chick can swim to the nearest branch or tree trunk and climb back up the tree into the nest.

Some people have called the hoatzin a living fossil and equated these claws with those of Archaeopteryx, the ancestor of modern birds that lived 150 million years ago. However, the claws are not unique among birds: some species of geese retain spurs on their wings into adulthood, and young European coots have a single claw on each wing that helps them climb back to the nest as well. It is more likely that the hoatzins claws are not a relic, but a recent adaptation to its rather precarious nesting site.

Hoatzins are remarkable for still another reason. Their diet consists strictly of vegetable matterleaves, flowers, and fruits. It is the only tree-dwelling bird that feeds its young on leaves. To handle this fibrous diet, the hoatzin has evolved a very large crop, or gizzard, in which it grinds up the tough cellulose fibers of the leaves. The crop is so large that it accounts for about one-third of the adult birds 28 oz (793 g) body weight.

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Hoatzin

Hoatzin

The hoatzin (Opisthocomus hoazin) is one of the world's most peculiar bird species . It is the sole member of its family, Opisthocomidae. It is peculiar enough to have defied taxonomists' best efforts for years.

This bird lives only in the rainforests of northern South America . Its feathers are dark brown on the back and lighter below, and chestnut-colored on its sides. The skin around its red eyes is a startling electric blue. Its head is topped by a crest of long chestnut-colored feathers.

The hoatzin builds its next of sticks in trees or large bushes, usually on boughs that overhang the water . Into this nest the female lays two or three (though sometimes as many as five) buff-colored eggs speckled with blue or brown. After an incubation period of 28 days, out of these eggs hatch some of most remarkable chicks in the order Aves.

Hoatzin chicks are naked, and proof of the old aphorism "a face only a mother could love." But beauty does not count: what does count is the tiny claws on the chick's wings. The claws help the chick to hold on as it moves through the branches. But even if it should tumble off the branch and fall into the water below, the hoatzin chick can swim to the nearest branch or tree trunk and climb back up the tree into the nest.

Some people have called the hoatzin a living fossil and equated these claws with those of Archaeopteryx, the ancestor of modern birds that lived 150 million years ago. However, the claws are not unique among birds: some species of geese retain spurs on their wings into adulthood, and young European coots have a single claw on each wing that helps them climb back to the nest as well. It is more likely that the hoatzin's claws are not a relic, but a recent adaptation to its rather precarious nesting site.

Hoatzins are remarkable for still another reason. Their diet consists strictly of vegetable matter—leaves, flowers, and fruits . It is the only tree-dwelling bird that feeds its young on leaves. To handle this fibrous diet, the hoatzin has evolved a very large crop, or gizzard, in which it grinds up the tough cellulose fibers of the leaves. The crop is so large that it accounts for about one-third of the adult bird's 28 oz (793 g) body weight.

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