Hoatzin

Hoatzin bird is a neotropical bird that is also commonly known as reptile bird, skunk bird, Canje pheasant or stinkbird. But the scientific identification of this bird is Opisthocomus hoatzin that belongs to the family of Opsithocomidae and of the order Opsithocomiformes. It is the only extant species of the genus Opsithocomiformes that is known. It is a tropical bird that dwells around slow-moving rivers and lakes of the Amazon basin and is the only member of the genus Opisthocomus. It is a class of Avas that is a primitive of chicken-sized native bird of the swamps in South America and still prefers to live in swamps, riparian forests and mangroves Amazon and Orinoco basins in South America. 

The taxonomic position of this family is greatly under debate among many specialists and is still very faintly clear. The chicks of the Hoatzin is especially known for the existence of the claws on the two digits of the wings. Therefore many scientists third to link the traits of the species with the fossil traits of Archaeopteryx belonged to dinosaur ear. They are the social bird that likes to stay in a flock and have a clumsy way of moving around and through the foliage. Their loud calls and very distinct appearance makes them easy to distinguish in the habitats.

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Description of Hoatzin

Hoatzin is considered to be the bird of the family Phasianidae and the subfamily Phasianinae because of their size. The average length of hoatzin birds is approximately 65cm (26in) with a long neck and a small head. The body mass of an adult hoatzin on average ranges from 0.8 to 1 kg (1.78 to 2.2 lbs). It has a striking blue head that is unfeathered and maroon eyes. They have a spiky crest that is reddish-brown in colour and has a long brown tail that has broad buff coloured patches at the tips. The upper part of the body is black with rust-brown edges and the tectrix (a set of feathers on a bird that covers the other feathers and helps the smooth airflow over the wings and tail) is buff coloured and also possess some buff streaks on the neck and the mantle. Their underpart is buff coloured as well but the under tail coverts covering the posterior orifice of the bird (that is the only opening for the digestive, reproduction and the urinary tract), the flight wings and covets of underwings are of reddish-brown chestnut hue that is only visible when they open their wings. The wings only support the small flights and thus the adults can fly up to a small distance.

The hoatzin birds are completely herbivorous and they are the only bird species that possess a digestive system that ferments the vegetation (like in cows and buffaloes) they eat that helps them to exclusively feed on the leaves and buds. They mostly like to feed on the swamp plants that are then ground and stored in a hugely enlarged pouch situated in the gullet of the hoatzin. Their digestive system has a close similarity with the herbivorous mammals that are basically large hoofed grazing animals. The name stinkbird is derived because of the foul odour that releases from their body due to the fermentation digestive process of the foliages they consume. The adults spend most of their leisure time digesting the food. A large rubbery thicken and the hard area around their breastbone area that is identified as callus acts as a tripod that restrains their body from falling when their stomach is swollen.

It is a very noisy species as it makes some rough and croaky sounds as their call that also includes hissing, grunting and groaning. Their calls are often associated and synchronized with mostly the spread of wings and other body movements. They do not show any sexual dimorphism and looks the same with the same features as well as characteristics.     

The Mysterious Origin of the Hoatzin

The hoatzins are now geographically restricted only to South America but that was not always the scenario. The studies of their ancestors’ habitats and the geographic range are believed to be in Europe and Africa that could also be their native place of emergence. Many of the biologists studying their evolution have theorized that by the time the options were emerging the tectonic plates started to drift and so the continents and also as they are poor fliers they might have immigrated employing rafting. 

Though the studies do not have a strong relevance, many of the scientists for s long time believes that many of the native swamp and chunks of floating soils were washed out by the sea floods and rain in ancient times. But these species have managed to float along the currents of the water of the Atlantic oceans and finally strike their permanent habitat in the Amazon forests of South America. 

Now these days in the Peruvian Amazon rainforests, these species are seen as individuals or in a flock with their babies. With the presence of the wing claws, the babies craw up to a surface by the alternating motion of their claws that are present in the opposite sides of their body that are otherwise very commonly seen among mammals. The fact that no other living bird, except the hoatzin bird, has the capability of crawling movement actually distinguish it from the other bird species.      

Hoatzin Habitat

The hoatzin is the strangest bird that is now only found in the Amazon rainforest of South America. Though it is believed that the native hoatzin habitat was in Europe and Africa from where they evolved and rafted through the Atlantic oceans and permanently found their habitation in the Amazon rain forests. They are topical bird species and therefore prefer to dwell near the water areas. The common hoatzin habitat is the swamps and the riparian forests of the Amazon as well as the Orinoco basins. They have also been seen and observed along the Atlantic coasts of Guyana, French Guiana and Suriname.  

Taxonomy and Evaluation

There was a German zoologist named Statius Muller who first described the hoatzin bird in the year 1776. With much of a debate of it is being a bird since it was identified due to its different characteristics that quite resembles the gazing mammal, it was finally given its own family, the Opisthocomidae. It also was then denoted with its individual suborder as Opisthocomi. Many a time it was associated with many species such as taxa, The Galliformes, doves, turacos, sandgrouse, seriemas, other Cuculiformes and the mousebirds. But in the year 2014, a study was published based on its whole genome sequencing, the hoatzins were recognized as the sister clad of the taxon composed of Gruiformes and Charadriiformes.

Behaviour 

Feeding

The hoatzin is a folivore that eats leaves, buds and a lesser degree of fruits and flowers of the plants that mostly grows in the marshy lands and along the riverine or any other waterline habitat where they are often found a dwelling. They usually move around clumsily through the bushes and the branches and is quite docile by nature but as they are reluctant to flush thus often allows the close approach. Earlier the species is believed to be consuming only the leaves of the mangroves and arums but now it is known for consuming leaves of over forty plant species. The only study that was conducted in Venezuela concluded that the diet pattern of the hoatzin birds comprises 82% of leaves, 10% of flowers and 8% fruits. But sometimes it accidentally feeds itself insects or the waste matter of other animals that are present on the leaves and the buds.

The digestive system of the hoatzin functions differently from the rest of the bird species. The bacterial decomposition or fermentation of the foliage it consumed takes place in the front section of the gut just like cattle and other ruminants functions. But unlike the ruminants that possess a paunch, the hoatzin has an inbuilt crop that is unusually large in size that has been folded into two chambers. Along with the two folded chambers, it also possesses a large single chambers oesophagus. Therefore its actual stomach and the gizzards are actually smaller than the other birds. The crop of the hoatzin bird is so big that it hinders the displacement of the flight muscle and a rigid along the breastbone that is attached to the flight muscle called keel of a thickened ventral plate. Thus it becomes detrimental to its flying capacity. Because of the aromatic property of various leaves that are then undergo bacterial fermentation releases unbearable manure like odour and thus it is only predated by humans for food at a dire need.

Defence Strategy

Due to their distinctive characteristics, they are easily coming under the radar of their limited predators but as both, parents tend to raise their young ones they often defend their young by hissing, hooting and yelping at the predators that commonly include capuchin monkeys and the tiaras. As the hoatzin is one of the best swimmers from the time they are born, often when the hoatzin sense some kind of threat the babies crawl out of their nest (hoatzin builds their nest near the waterside) and plunges below the water. But as soon as the area becomes safe again with the help of their claws beneath the wings they again climb up to the nest. 

Breeding 

The hoatzin usually attains their sexual maturity at one year of age whereas their lifespan in the wild ranges from 14 to 16 years whereas in captivity they tend to live much longer till 29 to 30 years. They usually prefer to mate during the rainy season and they prefer to build their nest on the branches of the trees that are located about 6 to 15 feet above the surface. After their mating, the incubation period for the female hoatzin lasts for thirty-two days in normal conditions. They lay two to three eggs at a time. After the eggs hatch both the male and the female hoatzin brood their young ones voluntarily. As soon as the chicks are born their wing claws become active and as any predator approaches them, the parent hoatzin fly and start hooting to distract the predator while the little ones crawl down the tree and dispatches into the deeper forest or underwater surface. Once the parents come back to the nest, they eventually climb up with the help of the wing claws. After the hatching the youngs one remain under the parental care till two to three weeks and then leave the nest to be on their own.

Conservation 

Though they are the rarest species, it is still not considered as endangered. Though the wild hunting of hoatzin by humans and cutting down their natural habitat have been the greatest threat to their survival for quite some time now all over South America. But the recent IUCN rating of the hoatzin is “least concern” in terms of conservation.

Fun Facts

1. The hoatzins are named stinkbirds due to the foul smell they release from their body due to the bacterial fermentation of the foliage they eat.

2. The newborn hoatzins are born with the active wing claws that help them crawl up and does the tree where their nest is built in times of danger.

3. They always create the nest that are near water and the wing claws of the younger ones prevent them from falling into the water. But they are also excellent swimmers.

4. In Guyana, hoatzin is their national bird and is called by the name Canje Pheasant.

Summary at a Glance

1. The scientific identification of this bird is Opisthocomus hoatzin.

2. It belongs to the family of Opsithocomidae and of the order Opsithocomiformes.

3. The average length of hoatzin birds is approximately 65cm.

4. The average weight of hoatzin birds is approximately 0.8 to 1kg.

5. They have a blue face, maroon eyes and spike rust-brown feathers on the head.

6. Have a long tail with reddish-brown colour with the upper part black and the tips have buff patches.

7. They have a giant crop where food is ground and then stored like grazing herbivorous mammals.

8. The bacterial fermentation starts at the frontal section of the gut and results in a foul smell like manure. 

9. They are believed to be the native of Europe and Africa but have eventually located in the Amazon forest either by rafting or by the displacement of the continents during the time of its evaluation.

10. They attain sexual maturity at the age of one and have a life span of 14 to 16 years in the wild and 29 to 30 years in captivity.