Photo: FWS/ Steve Hillebrand
(Grus americana )
DESCRIPTION: At about 1.5 m tall, whooping cranes are the tallest bird in North America. Adults are white with black primaries and a bare red face and crown. The bill is an olive-gray, eyes are yellow, and legs and feet are gray-black. Whooping cranes live an average of 25 years. They are often confused with sandhill cranes, snow geese and white pelicans.
STATUS: Whooping cranes were recognized as endangered in 1967 (Federal Register, March 11, 1967).
REASONS FOR CURRENT STATUS: The whooping crane population, estimated at 500 to 700 individuals in 1870 had declined to only 16 individuals in the migratory population by 1941 as a consequence of hunting and specimen collection, human disturbance, and conversion of the primary nesting habitat to hay, pastureland, and grain production. The main threat to whooping cranes is the potential of a hurricane or contaminant spill destroying their wintering habitat on the Texas coast. Collisions with power lines and fences are known hazards to wild whooping cranes. Cranes are susceptible to disease including avian tuberculosis, avian cholera, and lead poisoning.
REPRODUCTION AND DEVELOPMENT: Mate selection occurs on the wintering grounds or during migration. Whooping cranes are monogamous and normally pair for life; they will re-mate following the death of a mate. Each pair returns to the previous year's breeding territory but constructs a new nest. Whooping cranes generally arrive on the breeding grounds during late April. The southward migration begins anywhere from mid-September to mid-October and normally all cranes are on their wintering grounds by mid-November. Occasional stragglers may arrive in late December. Whooping cranes become sexually mature between four and six years of age. Whooping cranes generally lay two eggs, two days apart, in late April or early May. Both sexes incubate. Incubation period is between 29 and 34 days.
Whooping cranes fledge between 78 and 90 days. Young whooping cranes are fed by both parents for an extended time during their first fall and winter of life and are not independent until they are gradually abandoned by their parents the following spring. Usually only one chick survives.
Whooping cranes are omnivorous feeders. Some of the more common food items taken are crabs, clams, shrimp, snails, frogs, snakes, grasshoppers, larval and nymph forms of flies, beetles, water bugs, birds and small mammals. They eat over 58 species of fish.
RANGE: Historically, the primary breeding range of whooping cranes ranged from Alberta to Manitoba and south to Illinois. Whooping cranes were extirpated from north-central United States by 1890's and from Saskatchewan by 1929. Whooping cranes are believed to have wintered along the Atlantic coast, the southern United States, and down into central Mexico. Currently there are three wild populations of whooping cranes. One nests in the Northwest Territories of Canada and winters at Aransas National Wildlife Refuge in Texas. The second summers along the Rocky Mountains and winters in New Mexico. The third is a nonmigratory population in Florida. In the fall of 2001, an attempt was made to establish a fourth population that would migrate from Wisconsin to Florida. Seven fledgling whooping cranes were led to Florida using an ultralight aircraft.
POPULATION LEVEL: Currently, the only self-sustaining population is the migratory group that winters at Aransas National Wildlife Refuge. In 1995, the Aransas population reached approximately 130 individuals. It is hoped that the Aransas population will reach 500 individuals by 2018.
HABITAT: Whooping cranes breed and nest along lake margins or among rushes and sedges in marshes and meadows. The water in these wetlands is anywhere from 8 to 10 inches (20-25 cm) to as much as 18 inches (46 cm) deep. Many of the ponds have border growths of bulrushes and cattails, which occasionally cover entire bays and arms of the larger lakes. Nesting has also been reported on muskrat houses and on damp prairie sites. Whooping cranes prefer sites with minimal human disturbance. Wetlands provide the whooping crane with protection from terrestrial predators.
Whooping cranes winter on estuarine marshes, shallow bays, and tidal salt flats. The salt flats vary under differing tidal conditions from dry sandy flats to pools of salt water up to three feet (1 m) deep. Whooping cranes stop on wetlands, river bottoms, and agricultural lands along their migration route.
Potential predators of the whooping crane include the black bear (Ursus americanus), wolverine (Gulo luscus), gray wolf (Canis lupus), red fox (Vulpes fulva), lynx (Lynx canadensis), and raven (Corvus corax).
MANAGEMENT CONSIDERATIONS: Whooping cranes can tolerate very little human disturbance, especially during nesting, brood rearing, and during flightless molt (May to mid-August). Slight human disturbance is often sufficient to cause adults to desert nests. On wintering grounds, whooping cranes will tolerate human disturbance if it is not associated with obvious threats.
Some activities that disturb cranes include: draining wetlands, fencing, and plowing. In the winter, tour boats, waterfowl hunting, clamming, and angling cand disturb cranes.
Potential hazards to whooping cranes increase as human use of crane habitat increases. Barges carrying chemicals occupy the Gulf Intracoastal Waterway through the whooping cranes' wintering habitat every day. A spill or leak of these chemicals could contaminate the cranes' food supply, or poison or injure the cranes directly. Additionally, numerous oil and gas wells and connecting pipelines are located in the bays surrounding the cranes' habitat. Commercial fishing activities with nets is another potential hazard to whooping cranes.
Some causes of whooping crane mortality are illegal shooting, powerline collisions, collisions or entanglement in barbed wire fences, and diseases, especially avian tuberculosis and coccidia. Fecal accumulations and concentrations of coccidia oocysts at breeding sites on the nesting grounds may infect whooping crane chicks. When planning new powerline construction, wetlands and immediate adjacent areas frequented by whooping cranes should be avoided.
USFWS Whooping Crane Species Profile page
Information summarized from:
Lewis, J. C. 1995. Whooping Crane (Grus americana). In The Birds of North America, No. 153 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.