Hoatzin: Opisthocomiformes

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HOATZIN: Opisthocomiformes

PHYSICAL CHARACTERISTICS

The hoatzin (watt-ZEEN) is a medium-size bird measuring 24.5 to 27.5 inches (62 to 70 centimeters) and weighing 1.4 to 1.9 pounds (650 to 850 grams). Its face is bright blue and without feathers. It has thick eyelashes above bright red eyes. The bill is short and gray. The head is topped by a fan-shaped crest of long feathers that resembles a punk haircut. Neck is long and buff colored, as is the tip of the tail. Underparts are chestnut colored, upperparts are bronze and olive.

Very young hoatzins have two claws on each wing. These claws allow them to climb back up to the nests if they have been forced by predators to suddenly vacate the nest to seek shelter.

GEOGRAPHIC RANGE

Hoatzins are found in South America.

HABITAT

Hoatzins live in vegetation bordering water such as swamps, lakes, lagoons, streams, and rivers. Large populations can be found along the Amazon and Orinoco River systems. Hoatzins never live in altitudes above 1,640 feet (500 meters).

DIET

These herbivores (plant eaters) feed on little else than tree leaves. They like young leaves and shoots as well as flowers and buds. They eat throughout the day, with especially long feeding periods at sunrise and sunset. Hoatzins enjoy leaves from more than fifty plant species.

Hoatzins have stomachs similar to those of cows in that they ferment (break down for easier digestion) their food. In other birds with multi-chambered stomachs, fermentation usually occurs in the hindgut (end of the digestive system). But hoatzins have particularly large crops (pouches that resemble stomachs where food is held) containing enzymes that attack food and break it down. The remaining fatty acids are absorbed through the crop wall and used as energy. These bacteria become a source of protein, carbon, and other nutrients. The crop also breaks down toxins present in a number of the plant leaves eaten by hoatzins.

EVEN ECOTOURISM HAS DIFFICULTIES

Ecotourism—that ever-growing industry in which vacationers spend their money to take environmentally sound trips—may come with some not-so-pleasant side effects. According to a March 2004 report in New Scientist magazine, researchers claim that the wild animals ecotourism strives to protect are becoming overly stressed when forced to come into contact with humans.

The hoatzin is affected by ecotourism. In one study conducted by Princeton University and the Frankfurt Zoological Society, only 15 percent of hoatzin nests contained eggs in a reserve in Ecuador, compared to 50 percent in restricted areas. The tourist-attracting population also had double the amounts of a particular stress-induced hormone in their bodies. Researchers placed microphones in the birds' nests and determined that although the birds did not attempt to escape when tourists were nearby, their heart rates escalated.

Ecotourism is a billion-dollar industry that attracts millions of people to nearly ninety nations and territories that might otherwise suffer from lack of funding. The industry directly affects wildlife, habitats, and ecosystems as well as local cultures and people. The concern now lies in the backlash of ecotourism, and experts agree that before ecotourism includes a new hot spot on its list of destinations, it should conduct pre-tourism research and determine how human contact will affect the animals' welfare.

BEHAVIOR AND REPRODUCTION

Hoatzins live in units that include a monogamous (muh-NAH-guh-mus; one male to one female mate) pair and up to five nonbreeding helpers that are still around from the previous year's nesting efforts. This species is territorial, and all members of the social unit defend the territory by vocalizing, chasing trespassers, and fighting off intruders in the air.

During nonbreeding season, hoatzins leave their territory and form temporary flocks of up to 100 birds. The exception to this is when breeding territories result in unusually high reproductive success. These particular territories are defended year round. Hoatzins are noisy and make a variety of calls, including shrieks, hisses, grunts, and growls. Adults are able climbers but not so good at flying. Even so, they can fly up to 380 yards (350 meters) before needing a rest. As much as 80 percent of their time is spent roosting (resting) in trees.

Throughout the breeding season, hoatzins establish territories along waterways. They are colonial (grouped together) nesters, sometimes building as many as twenty-eight nests in one tree. Nests are actually unlined platforms of twigs on branches 6.5 to 16.5 feet (2 to 5 meters) high. As a rule, nests are built directly above water.

Females can lay one to six eggs, with two eggs being the most common. Eggs are laid after thirty to thirty-one days of incubation (keeping warm for hatching), which is performed by all members of the unit. When more than one egg is laid, incubation begins with the laying of the second egg. Eggs are laid one-and-a-half days to two days apart. Hoatzin chicks are nearly naked at birth, but are covered with down by twenty days. The crop of a newborn is sterile (free of bacteria). Bacteria forms within the first two weeks as adults feed the chicks.

Newborns are cared for continuously by all members of the social unit for the first three weeks of life. If left undisturbed by predators, nestlings will venture from home at two to three weeks of age. If predators approach, young will drop into the water for protection. They swim underwater and use those wing claws to make their way through aquatic vegetation. Once out, however, they will not return to the nest. Young hoatzins are able to fly around fifty-five to sixty-five days. By day 100, they shed their wing claws.

Hoatzins breed during the rainy season. Monkeys are the greatest enemies of this bird. In captivity, the hoatzin can live up to thirty years.

HOATZINS AND PEOPLE

The local name given to this bird in Guyana is "stinking pheasant" because the strong odor of the hoatzin is similar to the smell of cow manure. The odor comes from the fatty acids in the crop. The odor prevents the hoatzin from being hunted for its meat, but hoatzin eggs are consumed by some local populations. The meat is used for bait, and feathers are used to make fans. Locals in the Amazon make a soup from the hoatzin to help relieve asthma.

CONSERVATION STATUS

Hoatzins are not threatened. However, conservationists are concerned over the loss of habitat due to industrial pollution and the conversion of land for agricultural use.

FOR MORE INFORMATION

Periodicals:

Brown, Nancy Marie. "What's a Hoatzin?" Research/Penn State 27, no. 2 (June 1996). Online at http://www.rps.psu.edu/jun96/hoatzin.html (accessed on June 11, 2004).

Zahler, Peter. "Crazy Like a Hoatzin." International Wildlife Magazine (July/August 1997). Online at http://www.nwf.org/internationalwildlife/hoatzin.html (accessed on June 11, 2004).