Whooping crane

Appearance

An adult whooping crane is white with a red crown and a long, dark, pointed bill. However, immature whooping cranes are cinnamon brown. While in flight, their long necks are kept straight and their long dark legs trail behind. Adult whooping cranes' black wing tips are visible during flight.

On average, the whooping crane is the fifth-largest extant species of crane in the world. Whooping cranes are the tallest bird native to North America and are anywhere from the third to the fifth heaviest species on the continent, depending on which figures are used. The species can reportedly stand anywhere from 1.24 to 1.6 m in height. Wingspan, at least typically, is from 2 to 2.3 m. Widely reported averages put males at a mean mass of 7.3 kg, while females weigh 6.2 kg on average. However, one small sample of unsexed whooping cranes weighed 5.82 kg on average. Typical weights of adults seem to be between 4.5 and 8.5 kg. The body length, from the tip of the bill to the end of the tail, averages about 132 cm. The standard linear measurements of the whooping cranes are a wing chord length of 53–63 cm, an exposed culmen length of 11.7–16 cm and a tarsus of 26–31 cm. 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; the great white heron, which is a morph of the great blue heron in Florida; and the wood stork. All three other birds are at least 30% smaller than the whooping crane. Herons and storks are also quite different in structure from the crane. Larger individuals of sandhill crane can overlap in size with adult whooping cranes but are obviously distinct at once for their gray rather than white color.

Their calls are loud and can carry several kilometers. They express "guard calls", apparently to warn their partner about any potential danger. A crane pair jointly calls rhythmically after waking in the early morning, after courtship, and when defending their territory. The first unison call ever recorded in the wild was taken in the whooping cranes' wintering area of the Aransas National Wildlife Refuge during December 1999.

Distribution

At one time, the range for the whooping crane extended throughout midwestern North America as well as southward to Mexico. By the mid-20th century, the muskeg of the taiga in Wood Buffalo National Park, Alberta and Northwest Territories, Canada, and the surrounding area had become the last remnant of the former nesting habitat of the Whooping Crane Summer Range. However, with the recent Whooping Crane Eastern Partnership Reintroduction Project, whooping cranes nested naturally for the first time in 100 years in the Necedah National Wildlife Refuge in central Wisconsin, United States, and these have subsequently expanded their summer range in Wisconsin and surrounding states, while reintroduced experimental non-migratory populations have nested in Florida and Louisiana.

Reproduction

Whooping cranes nest on the ground, usually on a raised area in a marsh. The female lays 1 or 2 eggs, usually in late-April to mid-May. The blotchy, olive-coloured eggs average 2½ inches in breadth and 4 inches in length, and weigh about 6.7 ounces. The incubation period is 29–31 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 Gulf coast of Texas, United States, near Rockport on the Aransas National Wildlife Refuge and along Sunset Lake in Portland, Matagorda Island, Isla San Jose, and portions of the Lamar Peninsula and Welder Point, which is on the east side of San Antonio Bay.

The Salt Plains National Wildlife Refuge in Oklahoma is a major migratory stopover for the crane population, hosting over 75% of the species annually.

As many as nine whooping cranes were observed at various times on Granger Lake in Central Texas in the 2011/2012 winter season. Drought conditions in 2011 exposed much of the lake bed, creating ample feeding grounds for these cranes just as they were taking their autumn migration through Texas.

Food

These birds forage while walking in shallow water or in fields, sometimes probing with their bills. They are omnivorous but tend to be more inclined to animal material than most other cranes. Only the red-crowned crane may have a more carnivorous diet among living cranes. In their Texas wintering grounds, this species feeds on various crustaceans, mollusks, fish, small reptiles and aquatic plants. Potential foods of breeding birds in summer include frogs, small rodents, small birds, fish, aquatic insects, crayfish, clams, snails, aquatic tubers, and berries. Six studies from 1946 to 2005 have reported that blue crabs are a significant food source for whooping cranes wintering at Aransas National Wildlife Refuge, constituting up to 90 percent of their energy intake in two winters; 1992–93 and 1993–94.

Waste grain, including wheat, barley, and corn, is an important food for migrating whooping cranes, but whooping cranes don't swallow gizzard stones and digest grains less efficiently than sandhill cranes.

Predators

Their many potential nest and brood predators include American black bear, wolverine, gray wolf, cougar, red fox, Canada lynx, bald eagle, and common raven. Golden eagles have killed some young whooping cranes and fledglings. Due to their large size, adult birds in the wild have few predators. However, American alligators have taken a few whooping cranes in Florida, and the bobcat has killed many captive-raised whooping cranes in Florida and Texas. In Florida, bobcats have caused the great majority of natural mortalities among whooping cranes, including several ambushed adults and the first chick documented to be born in the wild in 60 years. Adult cranes can usually deter or avoid attacks by medium-sized predators such as coyotes when aware of a predator's presence, but the captive-raised cranes haven't learned to roost in deep water, which makes them vulnerable to ambush. As they are less experienced, juvenile cranes may be notably more vulnerable to ambushes by bobcats. Patuxent Wildlife Research Center scientists believe that this is due to an overpopulation of bobcats caused by the absence or decrease in larger predators that formerly preyed on bobcats. At least 12 bobcats have been trapped and relocated in an attempt to save the cranes.

Cultural

In the season one King of the Hill episode Straight as an Arrow, Bobby Hill incapacitates an endangered Whooping Crane, one of five left in the world. They mistake it for being dead, and spend the episode trying to get it out of the nature preserve to bury it.

In the book Even Cowgirls Get The Blues by Tom Robbins, the Whooping Cranes and their migration habits play a significant role leading to the climax of the story.