Whooping Cranes
Last Update/Review: June 17, 2002
Status | Description | Habits | Reproduction | Food | Limiting Factors | Management and Outlook
Status
Whooping cranes are perhaps the best known endangered species in North America. They have become the symbol of our efforts to protect and restore wildlife species that are threatened with immediate extinction. whooping cranes are classified as endangered throughout Canada and the United States. The Alberta Wildlife Act lists them as endangered animals in Alberta.
Historically, whooping cranes were found throughout much of central and western North America. Breeding populations used the area from central Illinois northwestward to the Arctic coast in the Mackenzie River area. The birds wintered along the coast of the Gulf of Mexico from Florida to central Mexico. Although widely distributed, whooping cranes were never numerous. In the late 1800s (when accurate numbers are first available), the population was approximately 1500 birds and most of the breeding population was concentrated in the aspen parkland and prairie regions of western Canada and the United States.
The species declined markedly as human settlement and development spread westward. By 1941 a total of 21 whooping cranes remained of which only eight or ten were in breeding pairs. Fifteen of these birds migrated to a then-unknown breeding area in northern Canada while the remaining six birds stayed in Louisiana year-round. In 1954 the breeding area was found in Wood Buffalo National Park (WBNP).
Tremendous conservation effort since 1938 has resulted in a slow increase in the whooping crane population. The increase was not steady and there were setbacks. However, by March 1990, the total population had climbed to 217 birds: 146 (including at least 32 breeding pairs) migrated annually between Wood Buffalo National Park and Texas,13 migrated between Idaho and New Mexico, and 58 were in captivity. Unfortunately, the small population in Louisiana was destroyed in a hurricane in 1949.
The current breeding distribution of wild whooping cranes is restricted to a small area in the northern part of WBNP, near Fort Smith, N.W.T. The population is migratory and winters in and around Aransas National Wildlife Refuge on the Gulf coast of southern Texas. The experimental population in Idaho has not bred successfully and its numbers are decreasing (see Management and Outlook).
Description
Adult
whooping cranes are indeed an impressive sight. At 1.3 m, they are
the tallest birds in North America. Whooping cranes are large, snowy
white with black wingtips, and have a wingspan that may reach 2.5 m.
They have a long neck, long dark pointed bill, and long thin black
legs. There is a bare patch of red skin on the head that extends backward
from the bill. The area below the bright yellow eye has short fine
black feathers and looks like a long dark moustache. There is also
a small patch of black feathers at the back of the head.
Shape is probably the best field identification feature of whooping cranes in Alberta. They are the only species of very large white bird (the black wingtips are hidden when the bird is standing) that has a long neck and walks or stands on long thin legs. The long bill also is distinctive and easy to see. Similarly whooping cranes are the only large white bird with black wingtips that flies with the neck straight out in front and the legs trailing far behind. These features separate them from trumpeter swans (all white, short legs), American white pelicans (short legs, flys with neck folded against shoulders), and snow geese (short legs, short bill).
Immature whooping cranes are rusty or cinnamon brown. As they get older, the brown gradually is replaced by white. Migrating young usually have a brown head and neck and a mixture of brown and white on the body. The wing feathers are white with brown tips. Young birds moult to the white and black plumage at 1 1/2 years. Only then do they have the bare red patches on the face.
Habits
Whooping cranes are found in Alberta between spring thaw and fall freeze-up. They arrive in the Wood Buffalo area in late April and leave in late September and October. Breeding pairs often are the first to arrive and the last to leave as there is just enough time in the short northern summer for the young to learn to fly (fledge) before the weather turns cold.
The 4000 km migration route generally cuts across northeastern Alberta and southwestern Saskatchewan into the United States and southward to Texas. It may take four to six weeks to cover the total distance as the birds stopover in staging areas along the way. These areas often are in wildlife sanctuaries. The best opportunity to see whooping cranes in Canada is in southern and central Saskatchewan during migration.
Whooping cranes are quite habitual in their behaviours. They migrate in pairs, family groups, or small flocks. Young birds stay with the adults through fall migration and winter but separate from the breeding pair during spring migration. Most whooping cranes do not breed successfully until five years old but may live up to 24 years in the wild. Nonbreeding birds spend the summer in pairs or small groups of three to five birds. They migrate north in the spring and spend the summer close to the breeding pairs but not within the nesting territories. During migration, the cranes make good use of thermal updrafts. They glide effortlessly and conserve energy as they rise and fall on the wind currents. When winds are favorable, they can stay aloft for up to 10 hours and cover as much as 750 km. Other than during migration, whooping cranes fly as little as possible, usually only far enough to reach new feeding areas.
Whooping cranes are territorial throughout the year. They are very aggressive in the breeding area and actively defend their nesting territory against other cranes. Adjacent nests are usually at least 1 km apart, and each territory (7 km² on average) contains a variety of marshes, ponds, and creeks with enough food for the pair and their young. During the winter, each family or pair defends a small territory (approximately 1.7 km²) that includes tidal salt marshes and flats, freshwater ponds, and some dry upland areas. These areas are good feeding and roosting sites.
The loud whooping or bugling, for which these birds were named, is usually heard early in the morning, during the spring courtship, and when birds are defending their nesting territories. Most cranes whoop when they are alarmed or upset. These deep, sonorous trumpeting noises are probably produced by forcing air through the great length of convoluted windpipe that lies coiled within the breastbone.
Reproduction
Each
year whooping cranes return to the same nesting area. In fact, some
pairs have been observed nesting in the same areas for 19 consecutive
years. One pair of cranes has nested in Alberta each year since 1977;
and three pairs nested in this province in 1990. The rest of the flock
are close by in the Northwest Territories. The nesting area in WBNP
is a large area of marshes and soft-bottomed potholes intertwined with
low-lying islands and spits covered with spruce and willow. The area
is very remote and undisturbed by humans.
Whooping cranes nest among dense stands of bullrushes in relatively shallow water. The nest is a large mound of dried bullrushes and, occasionally, sedges. It is approximately 1.2 m wide with a flat-topped central mound up to 13 cm above the water. Individual nests are often used for 3 or 4 years.
Adult whooping cranes mate for life but may accept a new mate if one of the pair dies. In early spring, dancing, which is part of the courtship performance, becomes noticeable and intensifies with the advent of spring migration. At the nesting ground, the adults carry out an elaborate courtship display, bobbing, weaving, jumping, and calling with their mates.
Soon afterwards, the female lays two, large light brown or buffy olive eggs that are heavily marked with dark brown or purple blotches, especially at the large end. Each egg is approximately 10 cm long, 6 cm wide, and weighs about 200 g.
Both adults are involved in incubating the eggs for 29 to 30 days. This gives each partner a chance to feed away from the nest. The eggs hatch in late May and early June. Within each nest, the eggs hatch at different times and the second egg or chick often is pushed out of the nest or starved. Newly hatched chicks can swim and the adults and young soon leave the nest, but stay within the nesting territory for the next two months. Young birds are able to fly 80 to 90 days after they hatch, but rarely take to the air before migration.
Food
Whooping cranes are fairly opportunistic (i.e., they take what they can get) and eat a variety of aquatic and terrestrial animals. During the summer, they eat snails, larval insects, leeches, frogs, minnows, and small rodents such as voles, lemmings, or shrews. In addition, they can take larger food such as blackbirds and ducklings and occasionally they eat berries or scavenge dead ducks, marsh birds, or muskrats. Some of the smaller food items are fed to the young birds as they flap their wings and beg until they are fed.
During migration, cranes often stop to eat aquatic animals, roots of plants, and waste grain in stubble fields. Once they arrive in Texas, whooping cranes eat crabs, clams, crayfish, small fish, snakes, acorns, and wild fruit.
Whooping cranes feed along the edge of shallow ponds, marshes, and creeks during the summer and in tidal marshes and sandflats during the winter. The strong thick bill is used to catch and kill food as the bird slowly wades through the water. Some adventurous cranes have been seen stalking prey on the ground or in the bullrushes.
Limiting Factors
The reasons for the initial decline in the whooping crane population are poorly understood. They probably involved a combination of habitat loss (draining and clearing marshlands) and human disturbance in the breeding areas. In addition, some birds were shot for their feathers and some eggs were taken by collectors. The results were disastrous for a species with a small population to begin with!
There
are also many natural factors limiting the number of whooping cranes.
Although young whoopers have high survival rates for their first 7
years (84% to 100%), they do not breed for at least 4-5 years, and
in many cases, for longer. Even then, a pair usually produces only
two eggs and raises one chick, so even healthy populations grow very
slowly.
Most deaths, other than those of chicks, occur during migration. Although these large birds are graceful fliers, they cannot execute quick maneuvers and collisions with powerlines are the number one cause of death of fledged whooping cranes. The frequent stopovers, necessary during migration, become more and more difficult to make as more land is developed for agriculture, industry, or settlement, and fewer suitable resting sites remain.
Whooping cranes are sensitive to repeated human disturbance in the nesting area. The only remaining breeding area in the wild is remote and inaccessible to most people. However, there appears (to the human eye) to be many such areas in the Mackenzie region of northern Canada. There probably is enough suitable habitat remaining in WBNP to support a much larger population of cranes, in an area where human activity can be regulated.
Unfortunately, suitable habitat in the wintering area is not so abundant. Aransas National Wildlife Refuge is surrounded by industrial, urban, and recreational developments and is estimated to have a capacity of 200 whooping cranes. That level could be reached in the next 10-15 years. There also are dangers in the wintering territory and 3-4 Whoopers are usually lost there each year. The disappearance of 9-11 whooping cranes in the winter of 1990-91 was especially alarming as only 13 young were produced the previous summer.
Management and Outlook
Whooping cranes are protected internationally in Canada, the United States, and Mexico under the Migratory Birds Convention Treaty. In Alberta, they are classified as Endangered Animals under the Wildlife Act, and it is unlawful for anyone to interfere with these birds or their nests at any time of year.
Current wintering habitats are protected within the Aransas National Wildlife Refuge in Texas and the last breeding area is within Wood Buffalo National Park. Both of these areas are managed, in part to promote and protect whooping cranes. For example, public access to the breeding area is strictly prohibited.
Public awareness and concern for whooping cranes has provided tremendous support for management efforts to increase the crane population. This concern has brought financial and political support as well as public participation in many projects.
Since 1954, when the breeding population of whooping cranes in WBNP was first located, there have been annual surveys of the number and location of breeding pairs and nonbreeding birds throughout the area. Surveys of wintering birds also are conducted annually in Texas. Public sightings along the migration route have also provided valuable information about the status of the wild population. People are encouraged to report any sightings of whooping cranes as quickly as possible to the local Natural Resources Service office or the Canadian Wildlife Service. Canada and the United States work closely together on all management actions affecting either the summer or winter grounds of the whooping crane.
An attempt to increase the survival rate of chicks began in 1967 when surplus eggs from Wood Buffalo National Park were removed to be incubated and the chicks reared in captivity. Eggs were tested for viability at the nest so that a live egg could always be left for the parents to rear. There are now two breeding populations of whooping cranes in captivity — one at the Patuxent Wildlife Research Centre in Maryland and one at the International Crane Foundation in Wisconsin. Facilities for a third colony began in 1991 at the Calgary Zoo in Alberta. The zoo hopes to receive its first whooping crane chicks and/or eggs in 1992 and to have birds producing eggs by 1996.
As long as whooping cranes use only one breeding area and one wintering area, there is a high potential for the loss of this species in the wild. The U.S. Whooping Crane Recovery Plan recommends establishment of two wild populations of at least 25 breeding pairs each in addition to the Wood Buffalo/Aransas population before this species can be downlisted from endangered to threatened status. Goals of the Canadian Whooping Crane Recovery Plan included an increase in the existing flock to 40 breeding pairs by the year 2000 and the establishment of a second flock of at least 5 breeding pairs in Canada, by the year 2010.
In 1975, a cross-fostering program began in which whooping crane eggs from Wood Buffalo National Park and Patuxent were placed in the nests of wild greater sandhill cranes at Grays Lake National Wildlife Refuge in Idaho. These foster parents hatched and raised their adopted whooping crane chicks. The young whoopers then migrated with their adopted parents and wintered in New Mexico. Initial results were promising, but the program has proved unsuccessful in the long term. The young female whoopers scatter widely and do not return to the breeding site where they were reared, nor do they form pair bonds with males when given the opportunity. The apparent lack of normal breeding behaviour is thought to stem from abnormal early learning (imprinting) in whooping cranes that are reared by sandhill cranes.
Several new programs for establishing new wild populations of whooping cranes are being considered. One would attempt to introduce captive-reared birds directly into the wild. Hand-rearing is a less expensive and more successful way to raise chicks from eggs, but young cranes with excessive exposure to humans do not survive when they are released. Fortunately, experiments with young sandhill cranes in Wisconsin may lead to a solution. These chicks have been hand-reared in "isolation" (with little or no exposure to humans) using crane puppets, mounted birds, live models and costumed humans, and they have had good survival rates following release.
There are also plans to release a small population of whooping cranes on the Kissimmee Prairie in Florida in the summer of 1991. Researchers believe that these birds will remain in Florida all year. Local predators such as bobcats and alligators could be a major limiting factor in this area, and only time will tell how whooping cranes fare in the Florida environment.
The outlook for the survival of whooping cranes is considerably brighter than it used to be. The population has slowly increased. Based on current management programs and information gained from previous efforts, the species should be able to continue to increase in number. However, they will continue to need complete protection and intensive management. The establishment of new populations is essential (so that all the whooping cranes eggs are not in one basket!). In addition, positive public support remains an essential ingredient in the efforts to restore whooping cranes and the variety of other species with declining or threatened populations.
