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Yukon Bison Management Plan
Yukon Wood Bison
Herd Size and Range
The first bison coming from Elk Island National Park arrived at the Nisling enclosure in March 1986. By 1992, four additional shipments had been received, making a total of 142 bison, with an even sex ratio.
The first release of bison from the enclosure took place in March 1988 and the last bison left the enclosure in the summer of 1992. In total, 170 bison were set free.
The wild herd has been growing at a rate of 15 to 20% per year, but in 1992/93, 36 bison had to be recaptured and moved to a game farm since they were causing problems along the Alaska Highway. In addition, eight bison were killed in collisions with vehicles and five were disposed of as "problem" wildlife. In all, the Alaska Highway situation set back growth of the wild herd by about two years due to the removal of 49 bison.
The herd has now recovered from this temporary setback and is currently (winter 1997/98) estimated at about 320. To fulfil the Yukon's commitment to the recovery plan, the herd must attain a viable population size of about 500. This makes annual monitoring of herd size critical. In addition to assessing the herd's size, its distribution must also be documented. Bison will not be tolerated in the vicinity of the Alaska Highway, and a bison-free buffer zone will have to be maintained to prevent the Yukon's Wood bison from mixing with introduced Plains bison of northern British Columbia or Alaska.
Herd monitoring is done by aerial census. Radio-collared animals have to be maintained in each subherd to make monitoring cost-effective. It is estimated that for a herd of 500 bison, at least 20 bison will have to have radio-collars. These collars must be replaced on an ongoing basis when they cease to function.
Genetics
The Wood bison is a recognized subspecies of the North American bison, closely resembling the Plains bison, but having some distinct morphological differences, such as larger size, longer horns and longer hair on the head, neck and shoulders. More important is its adaptation to the subarctic where the flora, fauna and weather differ from the environment the Prairie bison has evolved in. Mixing of these 2 subspecies is therefore undesirable, not only from the point of maintaining biodiversity, but also in the context of preserving a gene pool best suited for northern conditions.
As stated previously, Yukon's Wood bison are of Elk Island Park origin. This captive herd grew from the 24 bison originally transferred from Wood Buffalo National Park. Their identity as morphologically representative of Wood bison had been established (Banfield and Novakowski, 1960). While these bison are genetically pure, their genetic variability is very limited, being the offspring of 24 or fewer ancestors.
The 18 bison, which were relocated to the area north of Great Slave Lake, later called the Mackenzie Bison Sanctuary, showed phenomenal growth for many years. The herd is now estimated in excess of 1,300 bison. Its founder animals are different from those of Elk Island Park stock, and the herd has been exposed to a different selection pressure for over 30 years in an environment very similar to the Yukon with comparable winter conditions and predator pressure.
Every effort should be made to maintain the genetic purity of Yukon Wood bison and, if possible, enhance their genetic repertoire by the addition of Mackenzie herd genes.
Disease
Being social animals that live in herds, bison are more susceptible to certain transmittable diseases than solitary animals like moose. The following three highly contagious diseases are found in bison from Wood Buffalo Park. Their presence there has been a major obstacle in Canada's Wood Bison Recovery Program.
- Tuberculosis caused by Mycobacterium bovis
- Brucellosis caused by Brucella aborts
- Anthrax caused by Bacillus anthracis
Wood bison transplanted to the Yukon were disease-free. The animals received tests for tuberculosis and brucellosis as well as general inoculations for parasites prior to shipment. Additional testing has been carried out by Agriculture Canada on captive bison held in Yukon game farms, as well as on road kills and animals disposed of as "problem bison."
Every possible effort should be made to maintain the disease-free status of the Yukon's bison herd.
Habitat Protection
The Canadian Wildlife Service (CWS) studies selected the Nisling River watershed as the best bison habitat in the Yukon. However, after release from their enclosure, the bison only used the upper Nisling watershed and dispersed primarily southward into the Aishihik/Selkumun area, as well as the Hutshi Lake drainages. Currently, they occupy an area of about 4,000 square kilometres, but only a portion of this, perhaps 25%, is key habitat. The remainder consists of water, spruce forests, and alpine regions, which are used very little or not at all. Extrapolating from CWS's Nisling range assessment, the area currently used should support about 1,000 bison.
Bison are grazing animals that prefer tall, coarse sedges and grasses which occur in wet and dry meadows at low elevation or interspersed in buck brush communities. Such preferred habitats are relatively rare in the area and should be located, mapped and, if possible, protected. Some of these sites are also important for other species, such as caribou and waterfowl, which makes protection even more important.
In comparison to neighbouring jurisdictions, the Yukon's bison habitat is of lower quality in respect to both size of meadows and forage production. Therefore, the Yukon's bison population will not live in large groups of several hundred, but will consist of widely dispersed smaller groups of perhaps 20 to 30 on average. There may be merging of several groups at certain times, such as during the rutting period or winter, but such congregations will be rare and temporary.
Ecosystem Impacts
The reintroduction of a large mammal to an area from which it was absent for several hundred years will have an impact on the ecosystem. This impact may affect the terrain, the vegetation and other animals and people living in the area.
Concerns have been expressed by local residents that bison may compete with caribou and moose for forage plants and critical ranges as well as physically displace them. Scientific studies in this field are scarce, particularly when it comes to caribou. Such studies are necessary to fill this information gap and if possible, to assess and mitigate long-term effects of the introduced bison herd.
Legal Status
Wood bison are declared an "endangered species" under Section 19(3) of the Yukon Act (federal legislation), and a "specially protected species" under Section 11(2) of the Wildlife Act (Yukon legislation).
As a "transplanted population" they are not wildlife under the Umbrella Final Agreement.
At the national level, Wood bison were designated as an "endangered species" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) until 1987, when this designation was downlisted to "threatened" in recognition of the recovery efforts achieved. The draft national Wood Bison Recovery Plan, soon to be released, lists four free-roaming, healthy, genetically pure, independent populations of Wood bison of more than 400 each, as a condition for delisting Wood bison altogether. The Yukon made the commitment to contribute one of these four populations.
Internationally, Wood bison are listed in Appendix 11 of the Convention on International Trade in Endangered Species (CITES) which regulates their import and export for commercial purposes.
They are also listed in the Red Data Book of the International Union for Conservation of Nature (IUCN) which is a global catalogue of species at risk.
Compensation Policy
In 1992, the Department of Renewable Resources developed a compensation policy to pay for damages caused by bison and elk along the Alaska Highway.
This policy contains detailed criteria which must be met for compensation claims to be acceptable.
These criteria include the immediate contacting of a Conservation Officer when problems arise so that the damage can be assessed and minimized, and the problem animal can be dealt with. The claimant is also responsible for fencing-in hay piles in order to reduce depredation, and for implementing other preventative measures.
Hunting
In the first management plan for Yukon Wood bison (1989), the Yukon government made a commitment to consider the possibility of special permit hunts once the free-roaming herd grew to over 200 animals. The herd is currently estimated at 300 and has been growing at a rate of 15 to 20% annually.
In the absence of effective predators, the commitment to establish a herd size of about 500 and maintain it at that level will require hunting as the principle means of population control. Hunting can also be used to remove bison from areas where they are not wanted, such as along the Alaska Highway and in buffer zones, to prevent their mixing with Plains bison of Alaska and B.C. As well, certain bison may cause damage to private property or pose a threat to local residents and thus may have to be selectively culled.
An initial harvest of 2%, limited to bulls only, is proposed for 1998. This harvest will increase as the herd grows, in order to maintain it at the level of approximately 500 head. The harvest strategy (see page 19), which specifies details of this hunt, is also tied into a Highway Contingency Plan.
Interpretive Programs
Bison are impressive social animals that live in herds. They are the largest land mammals in North America, reaching weights of over one ton (909 kilograms). They prefer open habitat and are relatively tolerant of humans and related activities. These characteristics make them an ideal species for wildlife viewing and as a tourist attraction.
Few locations exist in the Yukon where large animals can be observed with any degree of predictability. This applies particularly to the summer months when most tourists come to the Yukon. In spite of all the problems the bison along the Alaska Highway were causing some years back, they had become quite a tourist attraction and the department received many positive comments to this effect.