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Whooping Crane

Whooping Crane images from Grzimeks Animal Life EncyclopediaGrus americana

Status: Endangered
Listed: March 11, 1967
Family: Gruidae (Cranes)
Description: Large wading bird with white plumage except for black primaries on wings; red facial skin.
Habitat: Wilderness wetlands.
Food: Crabs and clams.
Reproduction: Clutch of two eggs.
Threats: Diminished habitat.
Range: Colorado, Idaho, New Mexico, Texas, Utah

Description

The long-legged whooping crane is the tallest North American bird. Males stand 4.5 ft (126 cm) tall and weigh about 16 lb (7.3 kg); females weigh slightly less. Adult "whoopers" are white overall, except for red facial skin on the crown and side of the head. Black wing primaries are prominent in flight. The bill is dark gray, becoming lighter as the breeding season approaches. Legs and feet are usually black. The whooping crane's closest relatives in North America are five races of the sandhill crane (Grus canadensis).

Behavior

The whooping crane is thought to reach sexual maturity between four and six years of age. It is a monogamous bird that forms a lifelong pair bond with its mate. Toward the end of winter, pre-mating behavior begins with an increase of dancing displays and a loosening of territoriality. Pairs begin arriving at the breeding grounds in late April, returning to the same nesting site year after year. In late April or early May, the female lays two eggs, which are olive-buff and covered with dark, purplish brown blotches. Both parents share in the month-long incubation. The male sits on the nest during the day, the female at night. After a chick hatches, the family group stays close to the nest for about 20 days. Whoopers migrate southward from mid-September, flying by day and stopping to feed and rest at night. By mid-November cranes have arrived at the wintering grounds, where they remain for six months. Until January, cranes feed almost exclusively on blue crabs foraged from flooded tidal flats and sloughs. By then, most flats and sloughs have drained, and cranes move into shallow bays and channels to forage on clams and an occasional blue crab. Whoopers swallow clams and small blue crabs whole. They carry larger crabs ashore and peck them into small pieces.

The whooping crane is extremely wary of intruders during breeding season and has a very low tolerance for human presence. Whoopers are noted for being easily disturbed by passing aircraft, but there is some evidence that the skittish birds are becoming more tolerant.

Habitat

Nests are constructed in dense emergent vegetation, which grows in marshes, sloughs, prairie potholes, or along lake margins within large, undisturbed tracts of wilderness. Bulrush (Scirpus validus) is the dominant plant. Cattail, sedge, musk-grass, reed bentgrass, spike rush, and other aquatic plants are also common. Used nesting habitat is poorly drained and interspersed with numerous potholes, most with a soft loamy bottom. Potholes are separated by narrow ridges, which support an overstory of black spruce, tamarack, and willow. The crane's wintering grounds are salt flats, marshes, and barrier islands along the Texas coast. Marsh plants are dominated by salt grass, saltwort, popping cane, glasswort, and sea ox-eye. Inland margins of flats are dominated by Gulf cordgrass. Upland portions of the wintering habitat include sandy and gently rolling terrain, covered with live oak and redbay or long-stemmed grasses.

Distribution

The whooping crane once ranged over most of North America, from the Arctic coast south to central Mexico, and from Utah east to New Jersey, South Carolina, and Florida. Within historic times, the breeding range extended northwest from central Illinois through Iowa, Minnesota, North Dakota, southern Manitoba and Saskatchewan, to the general vicinity of Edmonton, Alberta. Breeding populations of whooping cranes were gone from the north-central United States by the 1890s. The principal historic wintering grounds were the tall grass prairies of southwestern Louisiana. Besides winter migrants, this region supported a small nonmigratory population around White Lake that was depleted by a severe storm in 1940. The last crane there was taken into captivity in 1950. Whoopers wintered along the Gulf coast in Texas and northeastern Mexico, primarily in the Rio Grande Delta, but also in the interior tablelands of western Texas and high plateaus of central Mexico, areas shared with sandhill cranes. Whooping cranes currently exist in three wild populations and at five captive locations. The only self-sustaining wild population, the Aransas/Wood Buffalo Population (AWP), numbered 138 birds in 1989, and 141 in 1993. The AWP nests in Canada's Wood Buffalo National Park (Northwest Territories), between the headwaters of the Nyarling, Sass, Klewi, and Little Buffalo Rivers. And winters along the southern coast of Texas—the Aransas National Wildlife Refuge (NWR), Matagorda Island, Isla San Jose, portions of the Lamar Peninsula, and Welder Point (on the east side of San Antonio Bay). Another, much smaller wild flock consisted in 1993 of eight birds reared by wild sandhill cranes (termed cross-fostered because they were raised by another species) in an effort to establish a migratory—Rocky Mountain Population (RMP), and one captive-reared bird released in an experiment. The third wild population consists of ten birds remaining from 19 captive-reared whooping cranes released in Florida's Kissimmee Prairie in February and December, 1993. This flock has been designated experimental nonessential and is the first step in an effort to establish a non-migratory population in Florida. In May 1993, whooping cranes were located at five captive sites. Two captive flocks are maintained by the U. S. Fish and Wildlife Service (FWS)—one at the Patuxent Wildlife Research Center, containing 55 birds, and one at the International Crane Foundation, containing 26 birds in December 1993. The Canadian Wildlife Service started a population at the Calgary Zoo, which, by 1993, contained 16 birds. Three birds reside at the San Antonio Zoological Gardens, and in 1993 a single bird was being held for treatment of avian tuberculosis at the Rio Grande Zoological Park in Albuquerque, New Mexico. As of the 1994 revised Recovery Plan publication, total captive population numbers came to 101. The overall totals for both wild and captive populations were 261 in December 1993. Management activities have resulted in a gradual increase in population numbers, from a low of 15 or 16 in the Texas wintering flock in 1941.

Threats

Conversion of the midwestern prairie pothole habitat to hay and grain fields rendered most of the whooping crane's original breeding range unsuitable, while increased human disturbance forced it from remaining nesting sites. From the 1870s to the 1920s, uncontrolled hunting took a large toll of whooping crane populations. When hunting was eventually stopped, cranes confronted a new threat—collision with power lines, which became the leading cause of whooping crane death.

Conservation and Recovery

Establishment of the Wood Buffalo National Park in 1922 by the Canadian government inadvertently assisted conservation of the Whooping crane. The crane's breeding grounds within the park were not discovered until 1954. In 1937, the Aransas Wildlife Refuge in Texas was established to secure one of the last viable whooping crane wintering areas. These wintering grounds were initially damaged by oyster dredging (later prohibited) and are now suffering from slow but constant erosion. An ongoing captive propagation effort was intensified in 1966, when the Patuxent Wildlife Research Center was established at Laurel, Maryland. Patuxent propagated a captive flock, whose eggs, as well as some collected from the Canadian population, were added to sandhill crane nests at Gray's Lake NWR. The eggs were incubated and hatchlings raised by sandhill cranes, which served as foster parents. When these whoopers reached sexual maturity, they formed pair bonds with their own kind and reproduced. In 1983, the FWS recovery team began a survey of potential reintroduction sites in the eastern United States and narrowed the field to two prime candidates: southern Georgia's Okefenokee Swamp, and Florida's Kissimmee Prairie. Captive reared whoopers were planned to be introduced into one of these areas, using techniques that have been proven in work with Mississippi sandhill cranes.

In 1985, the Canadian Wildlife Service and the FWS signed a memorandum of understanding (MOU) entitled "Conservation of the Whooping Crane Relating to Coordinated Management Activities." It provides a formal structure to the cooperative working relationships that have characterized the two nations' joint efforts in management and research of whooping cranes. The Canadian Wildlife Service published its Whooping Crane Recovery Plan in 1988; the plan complements FWS efforts and sets up the first recovery team ever organized for an endangered species in Canada. In cooperation with researchers at the Patuxent Wildlife Research Center, Canada established its own captive breeding population. A plan for Federal-State Cooperative Protection of Whooping Cranes was also approved in 1985, which outlined cooperative efforts between the FWS and 13 states where whooping cranes occur. The plan described proposed options for action when whooping cranes are observed in hazardous situations due to avian disease outbreaks, environmental contaminants, hunting activities, or when cranes are found injured, sick, or dead. Plan objectives were intended to provide additional protection to whooping cranes, especially during migration, and to increase the opportunities to recover and rehabilitate birds found injured or ill. Avian illness is a serious threat to the rare bird, and so in 1992, a whooping crane health management workshop was organized. Uniform health protocols were established for disease monitoring of captive and wild flocks and for pre-release and post-transfer disease screening. These are just a few of the numerous cooperative efforts ongoing to restore the rare, beautiful whooping crane.

Whooping crane photo by Ryan Hagerty, United States Fish and Wildlife Service The 1994 technical/agency draft revision of the Whooping Crane Recovery Plan noted that the interim recovery goal is downlisting to threatened status by 2020. A delisting goal was not identified at the time, but the downlisting goal is a minimum of 40 nesting pairs in the AWP (the only wild, self-sustaining population) and a minimum of 25 pairs occurring in self-sustaining populations at each of the two other discrete locations. These breeding pair levels must be attained or exceeded for 10 years before downlisting occurs. The recovery actions may result in migratory or nonmigratory populations similar to those that occurred historically in North America. Recovery actions outlined in the revised plan included the continued building of the AWP population to minimize the chance that a catastrophic event will eradicate the population; and the protection and management of all habitats. The plan also called for the attainment of breeding pair and productivity goals at two captive facilities in the United States and one in Canada to produce birds required for reintroductions and continued research to improve production of captive flocks, to identify appropriate reintroduction sites and to improve reintroduction techniques. In addition, the plan recommended the establishment of two additional self-sustaining wild populations and the maintenance of information and public information programs.

In March 2000, the first whooping crane born in the wild in the United States in 60 years was born in Kissimmee, Florida. However, in May, the chick was killed by a predator—possibly a bobcat.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P. O. Box 1306
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P. O. Box 25486
Denver Federal Center
Denver, Colorado 80225
http://www.r6.fws.gov/

References

  • Allen, R. P. 1952, 1956. The Whooping Crane. Research Report Number 3, (and supplement) National Audubon Society, New York.
  • The Associated Press. "First Whooping Crane Born in U. S. Wild in 60 Years Dies." CNN.com May 29, 2000. http://cnn.com/2000/NATURE/05/29/whooping crane.ap/ Date Accessed: July 21, 2000.
  • McNulty, F. 1966. The Whooping Crane. Dutton, New York.
  • U. S. Fish and Wildlife Service. 1986. "Whooping Crane Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.
  • U. S. Fish and Wildlife Service. 1994. "Whooping Crane Recovery Plan: Technical/Agency Draft Revision." U. S. Fish and Wildlife Service, Albuquerque.

Source: Beacham's Guide to the Endangered Species of North America, Gale. 2001.

Whooping Crane images from Grzimeks Animal Life Encyclopedia.

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