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Hoatzin

Opisthomocus hoazin

Opisthocomiforme Order - Opisthocomidae Family

BIOMETRICS:
Length: 61 - 66 cm; Weight : 700 - 900 gr.

LONGEVITY: 8 years (probably more)

DESCRIPTION:
Hoatzin is a colourful bird, with frizzy crest and long tail. We can say it has a “Prehistoric” appearance with particular “wing claws” similar to those present on the wings of the first known lizard-bird, the Archaeopteryx.

Small head is almost bare. Neck is long. Hoatzin has frizzy red-orange crest of about 4 to 8 cm long, starting on forehead. We can see a large bright blue area of bare skin around the eye. Eyes are red. Pale brown bill is short and relatively bulky. Legs and feet are blackish.
Both sexes are similar, with female slightly smaller than male, and with lower crest.
Nestlings have very thick dark brown down and two small claws on each wing which enables them to climb up branches a few times after hatching. These claws are situated on first and second phalanxes of wing articulation.
Young reach their sexual maturity at one year.

BEHAVIOUR:
Hoatzin adults gather in flocks of up to 10 to 50 birds, moving in trees, feeding on arum leaves and other marsh vegetation. They forage in the early morning and early evening. They spend much of their time roosting quietly and digesting their meal.

They live in family groups and small flocks, and they are gregarious all year round.
During breeding season, Hoatzin nests in colonies up to 28 birds, and some of them are helpers. They are subadults and adults, often young of previous clutches. Helpers are particularly active in territorial defence, and they assist in nest building, incubation, brooding, and feeding young. But only about 50% of territories have helpers.

FLIGHT:
Hoatzin is a poor flier. In spite of its large wings, it prefers to soar from tree to tree, with clumsy wing beats. It needs a lot of noisy efforts to cross a stream or move away when alarmed.
Studies tell that this bird has an important crop, which displaces some of breast flight muscles and keels of the sternum. Hoatzin is really a weak flier.  
Its poor capacity for flying doesn’t allow it to fly over terrestrial areas. It needs riparian vegetation for moving.

Chicks are fed by regurgitated plant matter that is oesophageal secretions. Nestlings and young are fed from adults’ crops, with a sticky, greenish, pre-digested mash, rich in bacteria to inoculate to young birds and which are necessary for their future. Young grow very slowly with the low nutrient value of this food.
If undisturbed, young leave the nest at about 2 to 3 weeks of age, and they are still brooded and fed for up to 2 months. They can fly short distances at 55 to 65 days. 
This species produces one brood per year, rarely two. But if clutch is lost, pair may nests again as long as rains continue.  

DIET:
If in most of birds’ species, food is broken up in the gizzard, the Hoatzin makes it in its well developed muscular crop.
Hoatzin feeds on certain marsh plants, such as leaves of arums (Aracea) and mangroves Avicennia, but they eat several other plants’ species. They usually choose young leaves, tender shoots and buds.
Hoatzin has a digestive system unique among birds, using bacterial fermentation to break down the plant materials they consume. That is the function of the crop, an enlargement of the oesophagus. This microbial fermentation converts plant cellulose included in consumed foliage into simple sugars.
Hoatzin has an unpleasant odour, due to aromatic compounds included in their vegetal food. This smell is like fresh cow manure, so, this bird is only hunted for food in extremely rare occasions.    

RELATIONSHIP WITH OTHER BIRDS’ FAMILIES
Hoatzin definitely got its own family, the Opisthocomidae, because it is unique.
In the past, this species has been related to several birds’ families, according to different anatomical particularities.
First, studies of skeletal characters suggested a relationship to “seriema” family, including rails and bustards.
Then, it has been related to turaco and cuckoo families, but these have zygodactyls feet (two toes forwards and two toes backwards). Hoatzin has typical foot with three toes forwards and one backwards.
The results of several DNA analyses were abandoned, due to erroneous data.
So, a possible relationship with doves was proposed, and also with flamingos, grebes, sandgrouses… These results were based on DNA, but these birds share some anatomical particularities, such as a fused series of thoracic vertebrae. And another feature seems to be important: doves and flamingos, as Hoatzin, are unique in feeding young oesophageal secretions.
Hoatzin is an odd species of tropical bird, also known as Hoactzin, Stinkbird or Canje Pheasant in Guyana. Hoatzin or Canje Pheasant is the national symbol of Guyana. Its name comes from the Canje River, in NE of Guyana, where this bird is found.

Fr: Hoazin huppé
All : Hoatzin
Esp : hoazín
Ital : Hoatzin
Nd : Hoatzin
Russe : Гоацин

Photographers:

Roger Ahlman
Pbase Galleries Peru and Ecuador

Didier Buysse
Vision d’Oiseaux

Marc Chrétien
MURINUS

Patrick Ingremeau
TAMANDUA

William Price
PBase-tereksandpiper & Flickr William Price

Yves Thonnerieux
NATUR’AILES

Text by Nicole Bouglouan

Sources:

HANDBOOK OF THE BIRDS OF THE WORLD Volume 3 by Josep del Hoyo-Andrew Elliott-Jordi Sargatal - Lynx Edicions, 1996, 821 pages - ISBN: 8487334202

Avibase

Arthur Grosset's Birds (Arthur Grosset)

Animal Diversity Web - (University of Michigan Museum of Zoology)

Wikipedia (Wikipedia, The Free Encyclopedia)

 

Home page

Page Family Opisthocomidae

Summary cards

 

Hoatzin has bronze olive upperparts, with fine buff streaks on dark hind neck, nape and mantle. Wings are large, and show pale buff patch on shoulders, becoming narrower and forming, with two more, fine pale buff wing bars. Long tail is black, with broad pale buff terminal band. When Hoatzin spreads its wings, we can see rich chestnut primaries with brown tips.
Underparts are buffy-white on throat and chest. Remaining underparts are rich chestnut.
VOICE: SOUNDS BY XENO-CANTO
Hoatzins communicate with discordant croaking. They are very noisy, uttering various hoarse calls. One of these calls is described as a “heavy wheezing”. They may vocalise in unison, with various hoarse cries, grunts, growls and hisses. These calls are accompanied by spreading wings and tail.

HABITAT:
Hoatzin lives in flooded forests along streams, mangroves, swamps, where they can find aquatic vegetation, mainly giant arums which are their preferred food. 

RANGE:
Hoatzin lives only in South America, in Amazon and Orinoco swamps, Guyana and Venezuela, south to Bolivia, Peru and Amazonian Brazil. This species is resident in its range and found from lowlands to 500 metres of elevation.
Hoatzin ranges in Amazon and Orinoco basins, and various streams and marshes within this aquatic complex. 

Both parents incubate the eggs, taking turns in sitting twice during 24 hours period. These changes occur with a ritual, with first expectant honking grunts from the incubating parent to other bird crash-landing on nearby branches. Change is very rapid. The incubation is rather to keep the eggs cool than warm. Parents have to pant continually because they have problems of refrigeration.
But Hoatzin likes warm, taking sun bathes perched in trees with spread wings and erected back feathers.
Males from adjacent territories may engage aerial battles, flying at each other from 3 to 5 metres apart, and colliding in mid-air, breast-to-breast, pecking and clawing at each other. They usually fall back into vegetation before to separate.
Conspicuous crest is used in defence of territory. Male’s crest is strongly erected, while it extends the neck and spreads its wings and tail. Two kinds of displays occur within breeding territory. They are defence strategy. Display copulation occurs all year round and is briefer than reproductive copulation which occurs only between breeding pair and not with helpers. Mated pairs are usually monogamous.      
Hoatzin is usually sedentary, performing some move according to food resources. They return to the same places after dry season.
PROTECTION / THREATS / STATUS:
Hoatzin is vulnerable to nest predation. Eggs and chicks are preyed upon by monkeys, tayras (mustelidae) and other mammals, but also by avian predators such as falcons, hawks and eagles.
In Brazil, indigenous tribal people collect the eggs for consumption; they may eat the birds, and take adults for their feathers and medicinal purposes.
At this time, with a large natural habitat in South America, populations of Hoatzins are probably secure. The most important threat is habitat loss, with conversion of this habitat into cultivated areas.
Hoatzins don’t live in captivity, because they lack their preferred food. They have to adapt to their captive diets, before performing successful captive breeding in the future.

Female lays 2, sometimes 3 creamy eggs, with blue, pink or brown spots. Incubation lasts about 28 to 32 days, by both parents which take turns in sitting.
Chicks hatch naked, but their down grows rapidly. They may leave the nest very soon after hatching, and they are able to climb on branches and vegetation. Chicks have an anatomical particularity. They have two claws on first and second phalanxes on wing articulation. They use these hooked claws for climbing on branches around the nest.

If alarmed or endangered, chicks may climb up in tree, using claws, bill and feet, but they can also drop into the water below the nest, swimming under the surface to escape predator. Then, they use again their claws to come back to the branches within their natal territory.

REPRODUCTION:
Hoatzin’s nest is located in a tree, above water. It is a loose platform made with sticks and dry twigs, at about 2 to 8 metres above water. They breed in community, and 2 to 6 adults may cooperate for building the nest and helping breeding pair.