Whooping Crane

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Whooping Cranes

Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Gruidae
Genus: Grus
Species: G. americana
Binomial name
Grus americana
Linnaeus, 1758

The Whooping Crane (Grus americana) is a very large and endangered crane. This species stands nearly 1.5 meters (5 feet) tall with a wingspan of 2.3 meters (7.5 feet). Males weigh on average 7.5 kg (16.5 lbs), while females weigh about 6.5 kg (14.3 lbs). It is the tallest North American bird and the only crane species found solely in North America.[1] This species' name comes from its whooping call.

Adults are white; they have a red crown and a long, dark, pointed bill while immature Whooping Cranes are pale brown. They have long dark legs which trail behind in flight and a long neck that is kept straight in flight. Black wing tips can be seen in flight on adult Whooping Cranes. The only other very large, long-legged white birds in North America are the Great Egret, which is over a foot shorter and one-seventh the weight of this crane, and the Wood Stork, which is about 30% smaller than the crane. Both are also very different in structure.

These birds forage while walking in shallow water or in fields, sometimes probing with their bills. They are omnivorous and slightly more inclinced to animal material than most other cranes. In their Texas wintering grounds, this species feeds on various crustaceans, molluscs, fish (such as eel), berries, snakes and aquatic plants. Potential foods of breeding birds in summer include frogs, mice, voles, flightless birds, fish, reptiles, dragonflies, damselflies, other aquatic insects, crayfish, clams, snails, aquatic tubers, berries, grasshoppers, and crickets. Waste grain is an important food for migratory birds.

The Whooping Crane is endangered mainly as a result of habitat loss. At one time, the range for these birds extended throughout midwestern North America. In 1941, the wild population consisted of 21 birds. Since then, the population has increased somewhat, largely due to conservation efforts. Recent estimates suggest that there are about 373 Whooping Cranes living in the wild, and another 145 living in captivity. The Whooping Crane is still one of the rarest birds in North America.

Their breeding habitat is the muskeg of the taiga; the only known remaining nesting location is Wood Buffalo National Park in Canada and the surrounding area. They nest on the ground, usually on a raised area in a marsh. The female lays 1 to 3 eggs, usually in late-April to mid-May. The blotchy, olive-colored eggs average 62.4 mm (2.5 inches) in breadth and 98.4 mm (4 inches) in length, and weigh about 189 grams (6.7 oz). The incubation period is 29-35 days. Both parents brood the young, although the female is more likely to directly tend to the young. Usually no more than one young bird survives in a season. The parents often feed the young for 6-8 months after birth and the terminus of the offspring-parent relationship occurs after about 1 year.

Breeding populations winter along the coast of Texas near Corpus Christi on the Aransas National Wildlife Refuge, Matagorda Island, Isla San Jose, and portions of the Lamar Peninsula and Welder Point, which is on the east side of San Antonio Bay.[2]

Among the many potential nest and brood predators include American Black Bear (Ursus americanus), Wolverine (Gulo luscus), Gray Wolf (Canis lupus), Red Fox (Vulpes fulva), Lynx (Lynx canadensis), Bald Eagle (Haliaeetus leucocephalus), and Common Raven (Corvus corax). Adults have very few predators, as even eagles are unlikely to be able to take one down. The Bobcat is the only natural predator known to be both powerful and stealthy enough to prey on adult Whooping Cranes away from their nesting grounds.

Attempts have been made to establish other breeding populations in the wild. One project by the United States Fish and Wildlife Service and the Canadian Wildlife Service was initiated in 1975 involved cross-fostering with Sandhill Cranes to establish a second self-sustaining flock. Although 85 chicks from the 289 Whooping Crane eggs transplanted into Sandhill Crane nests learned to migrate[3], the Whooping Cranes failed to mate and reproduce; the project was discontinued in 1989[4]. A second involved the establishment of a non-migratory population near Kissimmee, Florida by a cooperative effort led by the U.S. and Canadian Whooping Crane Recovery Team in 1993[5]. As of December 18, 2006, this population numbers about 53 birds[6]; while problems with high mortality and lack of reproduction are addressed no further birds will be added to the population.

A third attempt has involved the reintroduction of the Whooping Crane to a new flyway established east of the Mississippi river. This project uses isolation rearing of young Whooping Cranes and trains them to follow ultralight aircraft, a method of re-establishing migration routes pioneered by Bill Lishman when he led Canada Geese in migration from Ontario, Canada, to Virginia and South Carolina in 1993[7]. The cranes are costume reared from hatching, taught to follow an ultralight aircraft, fledged over their future breeding territory in Wisconsin, and led by ultralight on their first migration from Wisconsin to Florida; the birds learn the migratory route and then return, on their own, the following spring. This reintroduction began in fall 2001 and has added birds to the population in each subsequent year. As of January, 2007, there were 82 surviving Whooping Cranes in the Eastern Migratory Population (EMP), including 18 yearlings lead by ultralight aircraft in fall, 2006 and 4 yearlings released in Wisconsin and allowed to migrate on their own (Direct Autumn Release (DAR)). Fourteen of these birds had formed seven pairs; two of the pairs nested and produced eggs in spring 2005. The eggs were lost due to parental inexperience. In spring 2006 some of the same pairs have again nested and are incubating eggs. Two Whooping Crane chicks were hatched from one nest, on June 22, 2006. Their parents are both birds that were hatched and led by ultralight on their first migration in 2002. At just 4 years old these are young parents. The chicks are the first Whooping Cranes hatched in the wild, of migrating parents, east of the Mississippi, in over 100 years. One of these young chicks was unfortunately predated on the Necedah National Wildlife Refuge. The other young chick, a female, has successfully migrated with her parents to Florida. However, in early February, 2007, 17 yearlings in a group of 18 were killed by the 2007 Central Florida Tornados. All birds in that flock were believed to have died in the storms, but then a signal from one of the transmitter of "Number 15" indicated that it had survived. The bird was subsequently relocated in the company of some Sandhill Cranes.[8]

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