Coming Home

The spectacular grace of a Peregrine Falcon as it plunges from a cliff ledge to snatch a gull out of mid-air; the lonely call of a Swift Fox searching for a mate on a cold prairie night. Many sights and sounds that almost disappeared from our wilderness are now more common, thanks to complex reintroduction efforts aimed at conserving biodiversity and restoring balance to human-affected ecosystems.

Not since dinosaurs became extinct 65 million years ago has earth experienced such ongoing biodiversity loss as it has in recent years. Although many factors are involved, the loss, deterioration and fragmentation of habitat due to human development tops the list. While putting programs in place to conserve wild populations is the first proactive line of defence against extinction, in many cases numbers are so low scientists have no choice but to initiate recoveries by moving survivors to better locations, or taking them into zoos and other facilities for captive breeding. Stock from these captive populations can then be used to try to re-establish a viable, free-ranging population in the wild.

Although the World Conservation Union lists 200 reintroduction projects currently under way around the world, re-establishing animals in their original habitat is more than a matter of simply setting them loose and hoping they will go forth and multiply. It is a complex, long-term effort that poses a raft of difficult economic, social, and environmental challenges.

To prevent disease spread, social disruption and the introduction of alien genes, most reintroductions take place in areas where no remnant population exists. Where possible, reintroduction candidates are of the same subspecies or race as the original, since they are more likely to possess genetic traits adapted to the habitat. If sufficient wild stock exists, and studies show that moving some will not be detrimental to the existing population, it is easier and less expensive to catch and relocate animals than to captive breed them, since they already have the skills needed to survive in the wild.

Where numbers are insufficient, however, captive breeding may be the only option. One downside of this method is that, if few breeding pairs exist, the offspring produced will be from a very narrow gene pool—and may run the risk of magnified deficiencies. Fortunately, no such problems have been detected in captive-bred birds. Another is that captive breeding is costly. In addition to food, shelter and veterinary expenses, some species require artificial insemination or surrogate-type technologies to reproduce. Also, because most species of birds and mammals rely heavily on individual experience and learning as juveniles, they must be trained in essential skills. Success is more likely with captive-bred birds than mammals because avian behaviour tends to be more ingrained. At the same time, care must be taken not to get the animals too used to people, or they may invade human areas. Some degree of post-release care—including monitoring, supplementary feeding, veterinary care or predator control—may also be necessary, even over the long term.

Biologists with Environment Canada's Canadian Wildlife Service (CWS) are involved in several reintroduction efforts as members of multi-stakeholder recovery teams for species at risk. Their research contributes to an understanding of the causes behind a species' decline, the dynamics of its ecosystem, and its critical needs—including its required habitat, social behaviour, group composition, range size, shelter and food needs, and foraging and feeding behaviour. This kind of information is critical, because needs must be met, factors behind the decline minimized or removed, and the species protected over the long term across its entire range in order for the reintroduction to succeed.

When needs can't be met, such projects may have to be put on hold—as is the case with the Black-footed Ferret, a weasel-like mammal that was once common in the southwestern prairies and is no longer found in Canada. Although the ferrets have been captive bred in Canada using American stock, they can't be reintroduced here because there aren't sufficient populations of Black-tailed Prairie Dogs—the ferrets' main source of food—to support them.

A similar roadblock faces the Loggerhead Shrike, an endangered bird species whose population has dropped so dramatically in the last 25 years that an eastern subspecies now numbers 44 breeding pairs in the wild in Ontario and Manitoba. Although the loss of early successional grassland habitat is believed to be a major factor in the decline, information about other negative influences, including impacts along its yet-unknown migration routes and wintering grounds, is lacking. Therefore, first-generation birds from the existing captive breeding population won't be released into the wild until sufficient information is available and habitat recovery efforts have been initiated.

One of the greatest challenges in reintroducing Whooping Cranes to the wild is teaching them to migrate—a skill they would normally learn in the wild from their parents.

Another important element of any reintroduction is to ensure that the project is accepted and supported by the public, and by property owners and other stakeholders in particular. Since the support of landowners is essential to ensuring the long-term protection of habitat, endangered species management strategies must be understood and must incorporate other compatible land uses, where possible. If the species being introduced could pose a risk to property, these risks should be minimized and adequate provision made for compensation.

In Canada, support from ranchers has been integral to the successful reintroduction of the Swift Fox—North America's smallest wild dog—because uncultivated ranch land is the species' historic natural habitat. Once common in the dry grasslands between the southern Canadian prairies and Texas, the Swift Fox disappeared from the Canadian wilderness by the 1930s due to drought, loss of habitat, hunting, trapping, and the ingestion of poisons used for coyotes and rodents. In 1972, an Alberta couple began captive-breeding the animals from American stock, and over the next 30 years more than 900 foxes were released into southern Alberta and Saskatchewan. Despite heavy predation by Coyotes and Golden Eagles, a steady supplement of new foxes, some translocated from the United States, enabled the species to become established. Today, the wild population in Canada numbers around 300 animals, 80 per cent of which were born in the wild.

In Canada, support from ranchers has been integral to the successful reintroduction of the Swift Fox—North America's smallest wild dog—because uncultivated ranch land is the species' historic natural habitat. Once common in the dry grasslands between the southern Canadian prairies and Texas, the Swift Fox disappeared from the Canadian wilderness by the 1930s due to drought, loss of habitat, hunting, trapping, and the ingestion of poisons used for coyotes and rodents. In 1972, an Alberta couple began captive-breeding the animals from American stock, and over the next 30 years more than 900 foxes were released into southern Alberta and Saskatchewan. Despite heavy predation by coyotes and Golden Eagles, a steady supplement of new foxes, some translocated from the United States, enabled the species to become established. Today, the wild population in Canada numbers around 300 animals, 80 per cent of which were born in the wild.

An unusual situation exists with the endangered Vancouver Island Marmot, a small mammal that looks like a chocolate-brown groundhog. Although its ideal habitat still exists, the species has disappeared from two-thirds of its historic range over the past five decades, and now numbers fewer than two dozen animals in the wild because young marmots have taken to colonizing clearcuts instead of subalpine meadows. Clearcuts not only become unsuitable habitat as the forest regenerates, but also concentrate the marmot population, thereby making it more susceptible to predation.

While the birth of eight marmot pups in a zoo early this summer proved that the species will breed in an artificial environment, captive-bred marmots require a more natural setting to learn normal behaviours such as hibernation and fear of predators. To meet this need, a special breeding facility is being constructed on a mountain on Vancouver Island using funding from the provincial government, the forest industry and other private sources. The million-dollar facility will be operational by year's end, and the first marmots will be released in approximately three years. It is expected that the wild population will have to be supplemented with new members annually for 15 to 20 years.

Teaching wild behaviours to animals in captivity has been a focus of efforts to restore populations of endangered Whooping Cranes, which were down to only 16 birds in 1941—all part of a wild flock that breeds in the Northwest Territories at Wood Buffalo National Park and winters on the Gulf of Mexico in Texas. In 1967, biologists began collecting eggs and establishing captive breeding populations, so that all of the nearly 400 Whooping Cranes that now exist are descended from three females in the original flock. To equip these captive-bred cranes with foraging skills—and to exercise their long, injury-prone legs—young birds are regularly walked through wetlands as they grow up. Even so, newly released whoopers are provided with supplementary food for their first few weeks in the wild. Juveniles are raised in pens beside adult whoopers, so they will follow the examples set by the older birds during nesting season, and handled by caretakers wearing crane puppets, so they won't imprint on humans.

In the past few years, 175 captive-bred cranes have been introduced to Florida to establish a new, non-migrating wild population. This flock, which now numbers about 73 birds, is still 25-per-cent shy of its target size—largely because captive-bred cranes are naïve and vulnerable to predation by Bobcats. The flock has since been moved to more open ranchland, where there is less cover for the Bobcats, and young captive-bred cranes are being taught to favour short grass and to roost on water.

Establishing a new migrating flock of Whooping Cranes is a bigger challenge, since the birds learn to migrate from their parents, and none of the captive-bred birds has the benefit of experience. Experiments using Sandhill Cranes from the American mid-west as surrogate parents met with some success, but resulted in a large number of birds being killed in powerline collisions. Imprinting on the Sandhill Cranes also disrupted the whoopers' courtship, so they didn't form pairs. Sights are now set on establishing a new wild migratory flock in the eastern United States—where it is not likely to come into contact with the original western flock—by using an ultralight aircraft to show them the way. Already used successfully with geese, the method will be tested this summer with Sandhill Cranes, and could be used for whoopers as early as next year. The privately funded effort will cost about US$750,000 per year for 10 years.

Lessons learned through centuries of falconry helped ensure the successful reintroduction of the Anatum Peregrine Falcon—a subspecies that had disappeared from most of eastern Canada, southern Alberta, Manitoba and the interior of British Columbia due to the widespread and intensive use of organochlorines, particularly the pesticide DDT. Over a 25-year period beginning in the early 1970s, Environment Canada produced 1 550 young falcons through captive breeding and sent them for release into wild and urban areas across the country. To prevent disease, the breeding facility was established at an isolated location in Alberta and raised its own quail as food for the young falcons. Although the captive-bred young learned on their own how to hunt and migrate, fresh meat was provided daily for up to two months after they were released. In several instances, persistent predators—such as Great Horned Owls and goshawks—were relocated to give the young falcons a chance to survive.

Today, anatum peregrines have been re-established in every geographic region of Canada that had them historically, except the Okanagan Valley of British Columbia, where a reintroduction effort is in its third year. With about 500 breeding pairs across the country, the species was downlisted in 1999 from nationally endangered to threatened. Captive-bred nestlings are still being added to some nests in Alberta and Ontario that have fewer than four young, to bolster the population.

Other factors have been a challenge in re-establishing Canada's largest living terrestrial mammal—the Wood Bison. Once more than 160 000 strong, Wood Bison roamed parts of British Columbia, Alberta, Saskatchewan, and the Northwest Territories before severe winters, wolf predation, hunting, and interbreeding with Plains Bison diminished their numbers. In 1957, a CWS biologist discovered a herd of 200 wood bison in a remote northwestern corner of Wood Buffalo National Park—the last of their kind. Disease hit the area, and in 1963 some members of the herd were transplanted to wild ranges in the Mackenzie Bison Sanctuary, Northwest Territories, and in 1965 others went to fenced ranges in Elk Island National Park, Alberta.

In 1969, the Wood Bison herd at Elk Island became infected with disease and had to be subjected to a severe test and slaughter program before it could be used to establish captive breeding herds in other locations. In 1975, biologists began transferring stock from the source herd at Elk Island for release in other areas to establish free-ranging populations in the wild. Their numbers grew so rapidly that, in 1987, the Wood Bison was downlisted from endangered to threatened, and captive breeding was discontinued three years later.

Today, recovery efforts have established six disease-free, free-ranging wild herds in Canada totalling 2 800 Wood Bison, and six disease-free captive herds totalling 700 more. Although Wood Bison are now found in all regions where they originally ranged, available historic habitat has been severely limited by the conversion of lands for agriculture and development, and the need to keep the Wood Bison geographically isolated from diseased herds and Plains Bison. To help achieve Canada's recovery goal of four geographically separate herds of 400 each, biologists are currently negotiating to expand their efforts into Alaska and parts of eastern Siberia.

While proactive ecosystem-based conservation is the best method of managing wildlife over the long term, reintroduction efforts remain a crucial way of pulling species at risk back from the brink of extinction. Lessons learned as a result of the challenges posed by these and other projects will help to ensure that many of the birds and animals disappearing from our wilderness will once again call it home.

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