The whooping crane, once one of North America's most endangered species, has now become a success story for environmentalists. Cooperation between the Canadian and United States governments have made it possible for the birds to fly between the two countries and remain protected along their migration routes. Also, the work of biologists to create a captive population in recent years has lead to the release of these birds back into the wild.

In the 1800's, the breeding grounds for the whooping crane extended from central Illinois through northern Iowa, western Minnesota, northeast North Dakota, and into southern Manitoba, Saskatchewan, and Alberta, Canada. By 1941 however, the population of whooping cranes had declined to less than 15 birds. Scientists discovered that the reason for the decline in population were due to the destruction of habitat, human disturbance, and pesticide use. The whooping crane habitat consists mainly of wetlands and prairies; however, as more settlers moved west in the 1800's, the wetlands were drained and prairies were converted into farms for hay and grain production. Other factors leading to the decline included: collisions with power lines, illegal shooting (for meat & sport), avian tuberculosis, avian cholera, and lead poisoning. Another reason for their decline was that the pesticides used by farmers, caused the whooping crane eggs to become brittle. Early efforts to save this species have helped enormously.

In 1918, the Migratory Bird Treaty Act was passed in the United States which protected the whooping crane and other bird species from the threat of hunting. In 1922, Canada's Wood Buffalo Park, originally set up to help the declining buffalo population in the west, became a safe haven for whooping cranes. Currently, the cranes breed in this park during the spring and summer, then migrate to Aransas National Wildlife Refuge in Texas, which was set up specifically for the migrating whooping crane population in 1932. Biologists have helped out this species by practicing captive breeding methods. One of the biggest centers for captive breeding of the whooping crane is the Patuxent Wildlife Refuge in Maryland. Here, biologists allow the whooping cranes to mate, establish their territory and lay eggs, but once the cranes lay their eggs, biologists will remove the "extra" egg (whooping cranes traditionally lay two eggs, but only raise one chick). By removing this egg, biologists can increase production of eggs by three or four times.

What happens to the remaining eggs once the biologists remove them is that they are carried in a rigid suitcase (redesigned to be a portable incubator) to the propagation building. On the way there, the eggs must be handled as gently as possible because jostling and temperature extremes can kill the embryo. Once the eggs reach the propagation building, they are measured, weighed, and examined to make sure they are not cracked.

At this time, each egg is given an id number based on the parent's pen number and the order in which they were laid. After this is done, the egg is brought back to the crane pens and placed under a sandhill crane for incubation for ten days. After ten days have passed, biologists will remove the eggs, take it back to the propagation building and examine it again to see if the egg is fertile. If the egg is found to be fertile and healthy, the flock manager at Patuxent will check the charts to decide which pair of sandhills will incubate the egg for the next ten days. After the next ten days, the eggs are checked again to make sure they are developing normally and at 20 days, the eggs are placed in a mechanical incubator for the rest of the incubation time. Previously scientists used to take the "extra" egg from the whooping crane nests and transfer them to the nests of sandhill cranes who would act as surrogate parents to the young whoopers. Unfortunately, it was found in 1975 that the whooping cranes bred in this method were less likely to mate with other whooping cranes as they had gotten too used to their sandhill counterparts. So now, sandhill cranes are only used for a short period of the incubation of whooping crane eggs, and the young are given back to the parent whoopers to raise.

The future looks promising for the whooping crane. Now that their breeding grounds in Canada and their wintering grounds in Texas are on protected lands, they no longer have to fear hunters. Unfortunately, there are still many whoopers dying from collisions with power lines on their migration route. Scientists are stationed along the migration route to try and save these birds as they travel. Hopefully, as more power lines are moved underground and more research is done into the breeding of whooping cranes, the population will never be as low as it was in the early 1900's again.