Whooping Crane
Grus americana
Summary 2
The whooping crane (Grus americana), the tallest North American bird, is an endangered crane species named for its whooping sound. Along with the sandhill crane, it is one of only two crane species found in North America. The whooping crane's lifespan is estimated to be 22 to 24 years in the wild. After being pushed to the brink of extinction by unregulated hunting and loss of habitat to just 21 wild and two captive whooping cranes by 1941, conservation efforts have led to a limited recovery.[2] The total number of cranes in the surviving migratory population, plus three reintroduced flocks and in captivity, now exceeds 800 birds.
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.
The whooping crane is roughly the fifth largest extant species of crane in the world, on average.[3] Whooping cranes are the tallest bird native to North America and are anywhere from the third to the fifth heaviest species there, depending on which figures are used. The species can reportedly stand anywhere from 1.24 to 1.6 m (4 ft 1 in to 5 ft 3 in) in height.[4][5] Wingspan, at least typically, is from 2 to 2.3 m (6 ft 7 in to 7 ft 7 in).[4] Widely reported averages put males at a mean mass of 7.3 kg (16 lb), while females weigh 6.2 kg (14 lb) on average (Erickson, 1976).[6] However, one small sample of unsexed whooping cranes weighed 5.82 kg (12.8 lb) on average.[7] Typical weights of adults seem to be between 4.5 and 8.5 kg (9.9 and 18.7 lb).[3][4] The body length, from the tip of the bill to the end of the tail, averages about 132 cm (4 ft 4 in).[8] The standard linear measurements of the whooping cranes are a wing chord length of 53–63 cm (21–25 in), an exposed culmen length of 11.7–16 cm (4.6–6.3 in) and a tarsus of 26–31 cm (10–12 in).[3][9] The only other very large, long-legged white birds in North America are: the great egret, which is over a foot (30 cm) 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 (especially males of the larger races) of sandhill crane can overlap in size with adult whooping cranes but are obviously distinct at once for their gray rather than white color.[10][11]
Their calls are loud and can carry several kilometers. They express "guard calls", apparently to warn their partner about any potential danger. The crane pair will jointly call rhythmically ("unison call") 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 and is documented here [12]
The muskeg of the taiga in Wood Buffalo National Park, Alberta, Canada, and the surrounding area was 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. They 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 (60 by 100 mm), and weigh about 6.7 ounces (190 g). 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.[13]
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.[14]
The Salt Plains National Wildlife Refuge in Oklahoma is a major migratory stopover for the crane population hosting over 75% of the species annually.[15][16]
As many as nine whooping cranes were observed at various times on Granger Lake in Central TX 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.[17]
The whooping crane is endangered mainly as a result of habitat loss, but are also illegally shot in spite of potential substantial financial penalties and possible prison time.[18][19][20]
At one time, the range for these birds extended throughout midwestern North America. In 1941, the wild population consisted of 21 birds. Conservation efforts have led to a population increase; as of July 2010 there were about 383 whooping cranes living in the wild, and another 152 living in captivity. The whooping crane is still one of the rarest birds in North America. The United States Fish and Wildlife Service estimated the population at 505 whooping cranes in 2017.[21]
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.[31] In their Texas wintering grounds, this species feeds on various crustaceans, mollusks, fish (such as eel), 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[32] 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,[10] but whooping cranes don't swallow gizzard stones and digest grains less efficiently than sandhill cranes.
Sources and Credits
- (c) Sasata, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Grus_americana_Sasata.jpg
- Adapted by calgaryzoo from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Grus_americana
