Abstract
There are fifteen species of cranes in the world. Some of them are migratory, some are not. Most cranes are found north of the equator, but a few spectacular species are found in the southern hemisphere. More importantly, seven of the fifteen species of cranes are in extreme danger of extinction. The most endangered of all cranes is a bird found on our North American continent - the Whooping crane, Grus americana.
The Whooping crane is the tallest bird in North America. Adult birds reach a height of five feet and may have a wingspan of nearly eight feet from tip to tip, yet compared to the monumental struggle to save it from extinction, the Whooping crane's stature is diminutive.
From its beginning the Whooping crane has never been abundant. Some authorities have estimated the maximum population at less than two thousand birds. The former range is reported as from California to Kentucky and from northern Canada into Mexico. In order to comprehend the decline of today's population, we must first try to understand the complexities of the population in recent history.
In the mid 1800's, the Whooping crane was considered a favorite game fowl on the prairies of central Texas. This does not mean the bird was common; in fact, as early as 1850 it was recorded as a rare visitor except on the wintering grounds of southern Texas. In 1858 Spencer Fullerton Baird, considered an authority in his day, announced that not one skin of the Whooping crane reposed in a public museum of the United States. Many people consider this statement the beginning of the story. Ornithologists began to study its life history with fervor, museum personnel clamored for study skins, nests, and eggs, and the American scientific community began to realize how little was
known about this bird. Despite the increasing interest, the discovery of their primary nesting ground was a century away.
During those 100 years, the bird disappeared from its range at an alarming rate. The only known nesting grounds were abandoned for more secure areas to the North. In Iowa, the last nest was recorded in 1883; in Minnesota, 1889; Manitoba, 1900; North Dakota, 1907; Saskatchewan, 1922. The main cause of the decline seems to be human disturbance in the form of wetland drainage for development and agricultural production.
As a result of the shrinking range, the population began a steady decline that seemed irreversible. Then in 1937, when only a handful of Whoopers remained, the United States government declared the last wintering grounds a refuge to protect these birds 'during the critical non-breeding season. This winter feeding ground on the gulf coast of Texas, still used by the whooper today, is called the Aransas National Wildlife Refuge. This land had served as a private wildlife sanctuary since 1921 under the direction of Leroy Denman, a devoted conservationist, without whose foresight the Whooper may have vanished.
The Aransas reserve covers forty-seven thousand acres, but of that land, only five thousand acres is suitable Whooping crane feeding ground. Consider the possible consequences of a natural or man-caused disaster in this small area.
The swamps of Louisiana supported, at one time, the only known non-migratory flock of Whooping cranes. The rich waters teemed with life and were able to support a flock of these birds the entire year. Although their numbers were dwindling, their habitat was relatively safe and they may have been able to make a comeback. In 1939 there were thirteen birds, two more
than the year before, but in 1940, disaster struck. A hurricane ripped through the swamps leaving seven of the thirteen Whoopers dead. This was a blow from which the flock never recovered. The population decreased by one bird every year until only a single bird survived in 1947. This bird was finally captured in 1950 thus adding Louisiana to the growing list with the ominous heading "Former Range".
Now all concentration was focused on the Whooping crane population which had dipped to a low of 15 in 1942. It became more important to find the breeding ground. Every year planes were sent up to scan the vast Canadian wilderness and every year the planes came
back, full of disappointed conservationists. Then, on June 30, 1954, a helicopter was dispatched from Fort Smith to survey a fire that had broken out in Wood Buffalo Park in Northwest Territories, Canada. On the return trip the pilot, Don Landells, flew low over a marshy area near the Sass River. There he and Mr. G.M. Wilson, Superintendent of Forestry, saw below them a pair of Whooping cranes with a small, rustybrown chick. Thus, purely by accident, these two men made one of the greatest discoveries of the century. They had found the breeding ground of the Whooping crane.
Suddenly, several programs were initiated and the commitment to save the
Whooping crane gained momentum that has been building every since.
One of the programs, captive propagation, is based on theories that are controversial even today. The idea is to take Whooping crane eggs from the wild and raise the chicks in captivity under optimum conditions that afford the birds maximum security. These birds, in turn, will be persuaded to breed and, through techniques like artificial insemination and the manipulation of light cycles, produce offspring to be returned to the wild to bolster declining populations.
Dr. Ray C. Erickson has been a leader
of that philosophy and is now in charge of the captive flock of Whoopers at Patuxent Research Center. Dr. Erickson proposed to take one egg from every nest with two eggs in it at Wood Buffalo Park. This would not hurt the population, he argued, since usually only one chick is raised each year by a pair of whoopers. The chance that a pair will raise both chicks is slight at best.
Still, many people opposed the idea.
The thought of taking even one precious egg from the fragile wild population seemed to be the height of recklessness. It was, indeed, a gamble but to do nothing, it
was argued, was even more of a gamble.
In 1967, the Canadian government consented to Dr. Erickson's proposal and 6 eggs were airlifted from Wood Buffalo Park to the incubators at Patuxent Research Center. The operation must be considered a success. In each year that eggs were collected, instead of declining, the wild population actually increased and the chicks raised in captivity were a bonus.
These chicks, now adults, are forming pairs and beginning to breed in captivity. Their eggs are destined to be part of a bold experiment. The fertile eggs from this captive population as well as from Wood Buffalo Park, are being put into Sandhill crane nests at Grey's Lake in Idaho. The Sandhills raise the chicks, protect them, and teach them their migratory route to the Rio Grande River on the border of New Mexico and Mexico. This stable population of Sandhills has been the ideal foster-parent group for the valuable Whoopers. The major concern of authorities was whether the young Whoopers would imprint on sandhills or whether they would recognize each other as the same species.
The young Whoopers passed the test remarkably well. Whoopers are beginning to court other Whoopers. They call with each other and the chances that they will reproduce are very good. If they do, there will be two migratory populations of Whooping cranes for the first time in our lives.
Behind the scenes are many dedicated conservationists acting independently and as members of several organizations. Annual meetings are held by officers of the United States and Canadian wildlife services to set new policies. The Whooping Crane Advisory Group meets occasionally, as does the Whooping Crane Conservation Association, the Captive Crane Research Board, and the World Working Group on Cranes. In addition, many institutions have helped encourage the welfare of the Whooping crane. Among them are the San Antonio Zoo, the Audubon Park Zoo in New Orleans, Patuxent Research Center in Maryland and the International Crane Foundation in Baraboo, Wisconsin.
A five-foot tall bird with an eight-foot wingspan had done more than promote its own survival; it has awakened a conservation consciousness in the American public that has overflowed to many other species. To see a large, majestic white bird with great black-tipped wings flying north with neck and legs outstretched is indeed a thrill. For those people who do not find this an exhilarating sight, no explanation of its appeal is possible. For those of us who do, no explanation is necessary.