Crane, whooping

Grus americana

phylum: Chordata

class: Aves

order: Gruiformes

family: Gruidae

status: Endangered, IUCN Endangered, ESA

range: Canada, Mexico, USA

Description and biology

The whooping crane is so named because of its whooping, trumpet-like call. The tallest North American bird, it stands 5 feet (1.5 meters) tall and weighs almost 16 pounds (7.2 kilograms). It has an average wingspan of 7.5 feet (2.3 meters). This marsh or wetland bird has a snowy-white body, white wings marked with black tips, long dark legs, black feet, a red face, and a long, pointed yellow bill. Its diet consists of crabs, crayfish, frogs, rodents, insects, berries, and small birds.

The courtship behavior of whooping cranes is among the most unusual in nature. Their dance consists of strutting, leaping, head bobbing, wing flapping, and loud calls. Once a pair decides to mate, they mate for life. The pair requires a range of 300 to 400 acres (120 to 160 hectares) in order to find enough food and nesting sites.

In late spring, after building a nest on the ground among vegetation, a female whooping crane lays 2 light tan to green eggs. Both parents incubate (sit on or brood) the eggs for about 30 days before they hatch. The chicks' feathers are cinnamon colored. They will not develop their white adult plumage (covering of feathers) until their second summer. Of the two chicks born, only one will survive to adulthood. The first-hatched chick (born one to two days ahead of the other) usually attacks and drives away the younger chick from the nest.

Habitat and current distribution

Whooping cranes are migratory (they relocate on a seasonal basis) birds. They summer in the Wood Buffalo National Park in Northwest Territories, Canada. They begin migratingsouth in September in flocks of less than 10 birds. In November, they arrive at their winter home in the Aransas National Wildlife Refuge in Texas on the coast of the Gulf of Mexico. In April, they make the 2,600-mile (4,200-kilometer) trip back to Canada. About 300 whooping cranes currently exist in the wild and another 118 in captivity.

The birds prefer to build their nests in wetlands and marshes. In winter, they inhabit coastal lagoons and fresh and brackish (mixture of freshwater and salt water) marshes.

History and conservation measures

Scientists believe the whooping crane population was probably always small. They estimate that no more than 1,400 of the birds inhabited North America in 1870. Despite their small population, whooping cranes were found on the Great Plains and on both coasts of the United States. Before the American West was settled, they nested from Illinois to southern Canada and wintered from the Carolinas to Mexico.

By 1941, however, fewer than 20 whooping cranes existed in the world. Several factors contributed to their rapid decline. Many died as a result of hunting—for their meat or for sport. Others died from disease. The vast majority succumbed to habitat destruction. Over the past two centuries, more than half of all the wetlands that existed in the United States have been drained and filled in to create farmland, roads, and land suitable for homes and businesses.

Because each whooping crane couple requires a certain amount of territory, which they will defend from other whooping cranes, the population cannot grow unless they begin to use a different wintering ground. The Aransas Reserve in Texas is big enough only to sustain a population of about 200 cranes. It is surrounded by developed communities, so it cannot be made larger.

In 1967, the U.S. Fish and Wildlife Service (USFWS) began a whooping crane recovery program. Part of that program involved wildlife biologists (people who study living organisms) removing one of the two eggs from the birds' nests and placing them in the nests of sandhill cranes, which are closely related to whooping cranes. At first, the plan was successful. The sandhill cranes became "foster parents," incubating the eggs and then raising the whooping crane chicks as their own. However, when these whooping cranes grew to adulthood, they believed they were sandhill cranes and would not mate with other whooping cranes.

Biologists then began raising the captured eggs in captivity. Successful breeding programs were established in Maryland, Wisconsin, and Alberta, Canada. Beginning in 1993, captive-reared, nonmigratory whooping cranes were reintroduced to the wild on the Kissimmee Prairie in Florida. In the early 2000s, programs were initiated that taught the reintroduced cranes to migrate by leading them in ultra-light aircraft.

To protect existing migratory whooping cranes, the USFWS's recovery program includes the conservation of wetlands and other suitable habitat.