Restoring species to the wild
Two of the continent's most impressive animals make their home in the Yukon. Peregrine Falcons, the world's fastest raptors, return north every spring to nest on crags and cliffs around the territory. Wood Bison, the continent's largest land mammals, live year-round in the southern Yukon.
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To save this species, peregrine chicks were raised in captivity and then placed in the nests of wild adult falcons.
(photo: Dave Mossop)
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A few decades ago both Peregrine Falcons and Wood Bison were on the verge of extinction. It took huge commitments of time, effort and money to bring these animals back to their natural habitat. Now the tide seems to have turned, and peregrines and bison stand out as endangered species' success stories.
Both animals were listed as endangered on the very first list put out by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1978. This independent committee meets every April to decide which species are considered to be at risk in Canada.
The committee reconsiders "at risk" species every decade or so. The status of Wood bison was changed from endangered to threatened in 1988, and Anatum Peregrine Falcons followed suit in April, 1999. (The Tundra Peregrine Falcon, which lives on the Yukon's North Slope, is listed as vulnerable, an even lower-risk category.)
Even before COSEWIC began its work, Peregrine Falcons were known to be in serious trouble around the world, and the culprit had also been identified. The pesticide DDT, sprayed on agricultural crops, was being passed up the food chain.
Peregrines, at the top of the chain, were getting a strong enough dose to cause thinning of their eggshells, and the eggs would crack before the chicks were ready to hatch.
In 1969 the use of DDT was banned in North America, but this move was not enough to save the species. In 1975 it was estimated that only 34 pairs of peregrines remained in Canada.
Dave Mossop has been closely involved with the work to save Peregrine Falcons. Now a biology instructor at Yukon College, Mossop began working with the Yukon government as an ornithologist in 1975. He is a member of the national peregrine falcon recovery team that was set up to find ways to save the species.
Mossop figures that the species bottomed out in the Yukon between 1975 and 1980. "We could find only one bird along the Yukon River. I though they would go to extinction at that point," he says.
The plan to save peregrine falcons was based on captive-breeding. In 1971 the Canadian Wildlife Service established a captive-breeding facility in Wainwright, Alberta. Chicks from these birds were then placed in the nests of breeding pairs of wild falcons, a technique called fostering.
In 1978, the first captive-raised peregrine chicks were placed in nests along the Yukon River. Mossop says that it was a homecoming event as many of the captive-bred birds that had produced the chicks were from the Yukon.
At the start, Mossop was not convinced that the plan would be successful. "I thought we were fostering the last remaining pair," he said. But peregrines have staged a spectacular recovery, and populations in the Yukon are considered to be healthy.
Every five years peregrine falcon populations are surveyed across North America. In the 1995 survey, 30 volunteers checked nest sites in the Peel River and Yukon River watersheds, locating about 200 pairs of peregrines in the territory.
The news was equally good in other regions, and in 1996 the captive-breeding facility in Alberta was closed. More than 1,500 young peregrines hatched there had been placed with nesting pairs of wild peregrines across Canada.
The anatum subspecies is still listed as threatened in Canada, meaning that "it is likely to become endangered if limiting factors are not reversed" because some populations in southern Canada have not fully recovered.
"It's been tremendously gratifying to be involved with the recovery," says Mossop. "Peregrines have really been a flagship species for the modern conservation movement." But he also thinks that the most significant step in the recovery of peregrines was the first one.
"While it would be nice to think that 'We did it,' the big thing was the ban on DDT," he says. Mossop also points out that DDT continues to be a threat as it is still used in countries like Mexico where the falcons spend their winters.
Saving endangered species can be expensive work. In 1988 a national committee titled RENEW (REcovery of Nationally Endangered Wildlife) was established to oversee the recovery of species at risk in Canada. More money has been spent on peregrines and wood bison than on any other species.
According to RENEW's estimates, between 1988 and 1998 almost three million dollars was spent on restoring Anatum Peregrine Falcons to the wild. During the same ten-year period, just over twice that amount was spent on Wood Bison.
Almost 70 percent of the money is provided by government agencies. Recovery of wood bison has been expensive because it costs a lot of money to transplant a 1,000 kilogram animal.
Wood bison evolved in the ice-free area known as Beringia that extended north and west from the central Yukon during the last Ice Age. They were still abundant in North America until the late 1800s when hunting and disease had reduced their numbers to a few hundred animals.
Wood Buffalo National Park was created to protect this species in 1922, but later 6,000 Plains bison were released into the park. It was thought that interbreeding with Plains bison had completely wiped out Wood bison as a separate subspecies, but in 1959 a small herd of pure, healthy Wood bison were discovered in a remote area of the park.
These animals were used to establish two new herds in Elk Island National Park in Alberta and in the area north of Great Slave Lake. In 1986, the first bison were transplanted from Elk Island to the Nisling River watershed in the Yukon.
A total of 170 bison were released in the Yukon. The Canadian Wildlife Service was involved with this recovery effort until the herd numbered 200 animals. Now the Yukon's Department of Renewable Resources manages the bison, which number more than 500 animals.
Manfred Hoefs, the department's chief of habitat management and endangered species, is also on the national wood bison recovery team. He explains that the current goal is to maintain the herd's present size. The herd is growing by about 15 to 20 percent every year, and is considered healthy enough that the department is now allowing a limited number of the animals to be hunted.
While Peregrine Falcons and Wood bison are high profile examples of species "at risk," efforts are now being made to help less prominent species recover as well. RENEW recovery teams are working to restore more than 30 different species. Most of the work has been on vertebrates, but recovery teams are now working on other biota and are also taking an ecosystem approach in some jurisdictions.
For more information on endangered species in the Yukon, contact the Yukon Department of Renewable Resources at (867) 667-5671. The Environment Canada web site is also a good source of information at www.ec.gc.ca.
