Hoatzin: Opisthocomiformes

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 Newborn hoatzins are protected by adults for their first three weeks. They stay in the nest for those three weeks, unless a predator disturbs them. If they're disturbed, they drop into water (they can swim underwater) to escape, and they don't return to the nest again. (© François Gohier/Photo Researchers, Inc. Reproduced by permission.) 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.