Save the bison --Herd faces disease

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The world's largest herd of endangered wood bison, in the Northwest Territories (NWT), could be destroyed if infected by diseased animals roaming in the Wood Buffalo National Park, 212 km to the south.

The healthy buffalo are situated within the Mackenzie Wood Bison sanctuary near Fort Providence. The herd has grown to more than 2,000 animals from a mere 18 in 1963 and is continuing to expand. It is now feared the animals will soon spread out and come in contact with the infected group of buffalo.

Cormack Gates, bison ecologist for the NWT government, estimates young "pioneering" bulls from the Mackenzie herd have already ranged within 100 km of the diseased animals.

Wood Buffalo National Park contains 4,500 plains/wood buffalo, half of which are infected with either tuberculosis, or brucellosis, or both. Bob Redhead, an authority on bison at the national park, suspects the animals have been diseased since 1925. Around that time more than 6,000 plains bison from Wainwright were introduced to the 1,500 pure wood bison in Wood Buffalo National Park, 45,000 square km of wetland straddling the Alberta-NWT border.

"It's suspected they (the Wainwright bison) had the diseases when they came up here," says Redhead. "A herd of cattle probably passed the infection on to them while they grazed together.

Redhead is a member of the government task force which has come up with a 400 page report discussing the effect of tuberculosis and brucellosis on wildlife. Options to ensure the healthy bison remain unaffected are presented ? one solution involves corraling the diseased buffalo within 100 square km of fencing and allowing the disease to eliminate the infected animals. Once this process is complete the healthy buffalo would be released to roam.

Another option involves building a double fence around the perimeter of the Wood Buffalo National Park so the disease doesn't spread into the sanctuary. This solution would allow the Mackenzie bison to continue multiplying at a fast rate. Two fences built adjacent to each other are required in this situation so infected and healthy animals don't rub noses and pass along diseases.

Also, the Peace River would have to be fenced because animals can cross it in the water or swim in the summer. It's a federal law that waterways can't be blocked," Redhead adds. He points out that trappers and hunters would likely damage the fence and even if they don't "we have an average of 40 forest fires around here that would probably destroy it."

The last solution involves partial fencing in areas where the infected buffalo are known to congregate. But, similar problems are found with partial fencing as with complete fencing.

Redhead is uncertain as to what will be done. He feels it's likely the opinion of the status quo is to do nothing. Meanwhile, animals in the Wood Buffalo National Park will continue to die. The herd has been decreasing, but the disease is not to blame for all the deaths. "In 1974, 1,700 buffalo drowned in the Peace Athabasca Delta River and about 1,500 died the following winter of starvation."

"The flood that caused the drownings buried the bisons' food supply under the ice," according to Redhead. He points out it is difficult to assess the effect of the diseases on the herd. A death caused by a wolf attack may at first look as though it is unrelated to the disease, but since tuberculosis weakens animals gradually, it's possible those that have it have become too weak to defend themselves.

Brucellosis, on the other hand, is a genital tract infection. "It causes females to lose their calf in the first year . . . males become sterile in severe cases."

Redhead hopes action will soon be taken because the risk of connection between the healthy and diseased herds grows daily. However, the task force report is still in the draft stage and won't be released for another six months to a year.