Opisthocomus hoazin
Stink-bird
61 - 66 cm length 24 - 26 in width - weigh 816 g
A tropical bird found only in the Amazon, resembling a small
pheasant in size and appearance. The beak is thick, they have blood-red eyes encircled
by bright blue skin,. Adults are olive-colored with white markings above and red-brown
below. On the head a crest of feathers, a long neck and long tail feathers.
Its voice which sounds more like a heavy smoker's wheezing than a bird call.
They fly only reluctantly and put a lot of noisy effort into using their broad rusty
wings to cross channels or move away from perceived danger. Hoatzin prefer to climb
among branches using their wings for balance, they cannot grip with their feet.
The hoatzin is one of the strangest living birds, and seems to be a link with birds that
became extinct millions of years ago, and even shows similarities to
the first known bird Archaeoptery.
There is much debate as to which group the hoatzin belongs. Conservative systematists
have the Hoatzin in the Galliformes, based on osteological and
immunological data , biochemical evidence (both egg white proteins and
DNA-DNA hybridization, behavioral studies have shown an
affinity with the Cuculiformes (cuckoos and relatives), and
Sibley & Monroe consider it within a 'parvorder' in
the midst of their various cuckoo/ani groupings definitely
related to the cuckoos, although it may not itself be a
cuckoo. It's not even closely related to the galliforms.
The hoatzin has many features different from cuckoos and from other birds, like:
It is the only bird that has a fore-gut, for fermentation in the crop, with bacteria, to help it
digest cellulose, and an enzyme to extract nutrients from the bacteria, the hoatzin must
eat a great deal of its high-cellulose, leafy fare then sit around for long periods for its
digestive system to extract the nutrients the bird needs.
Hoatzin have a large, rubbery callous the size and shape of a human thumb
joint on the end of the hoatzin's sternum, or breastbone. After a gluttonous bout of feeding,
the bird squats down and rests its distended crop against a branch,
using the callous as a tripodlike third leg.
Born with hooked claws at the bend of each wing, useless to the heavy adult bird, they
are used by the young to scramble among the branches near the nest- much like the
Archaeopteryx must have done millions of years ago.
Gender differences:
Females are slightly smaller and have a lower crest but
male and female hoatzins are nearly indistinguishable from each other.
Habitat:
The hoatzin lives in riverside forests in northern half of South America.
in vicinity of swamps, mangroves, lowland flood forest,
river banks, oxbow lakes, where aquatic vegetation and giant arums
are plentiful
Diet:
mainly arum and mangrove leaves,
some flowers and fruits of more than 50 species of marshland plants.
Reproduction:
Hoatzins live in a colony of 10 to 20 members.
The nest is built on branches overhanging water a loose stick
platform constructed two to eight meters above water
of short twigs of roughly pencil thickness.
Mateing is year round with a peak just before the rainy season in
July and August and occurs in groups of two to six birds.
2 to 3 eggs two inches long are laid. The eggs are pale in color, covered in light brown
or blue speckles and blotches, incubation lasts 28 days
During breeding, Hoatzin live in small groups of two to ten; a few of which are breeders
and the others are 'helpers'. The entire group incubates the eggs, taking turns working to keep
eggs cool not warm as one would expect, and cares for young, which are fed
from the crop of adult caretakers. Nestlings are fed regurgitated matter. After 10-14 days
the babies start to feed themselves.
If danger threatens, the parents usually abandon the nest for the safety
of dense bushes nearby. The chick, is left to its own devices
Young hoatzin are unusual in that they leave
their nest soon after hatching and move about using two
hooked claws at the bend of each wing.
The main function of the wing claws, is to assist the young
hoatzin in times of peril. The nestlings scrambles through the branches to
thicker cover or drops to the water below. The nestlings are
good swimmers. In the water, the young bird quickly
swims into the tangled vegetation on the bank then climbs
up the foliage back to the nest area.
Other:
Because of the use of the crop for fermentation the bird has a musky odor some
describe as a manure like smell.
As the chick grows, it loses use of it’s wing claws, learns to fly and loses the
ability to swim. It continues to use its spread wings for balance as it
scrambles about .
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