When bison are ill
Diseased herd keeps park officials busy

Terry Halifax
Northern News Services

Yellowknife (Jan 24/00) - When nearly 7,000 diseased bison were introduced to Wood Buffalo National Park between 1925 and 1928, a problem was created that continues to confront biologists and park managers.

The bison, brought in from Wainwright, Alta., more than 70 years ago, were infected with tuberculosis and brucellosis. These diseases quickly spread to the resident herd.

Bison biologist Troy Ellsworth said the decision to move the diseased animals into the newly-founded reserve was made by politicians, without regard to the implications of mixing the diseased bison with the healthy.

"They knew they had brucellosis prior to shipping and that's where there is debate on ethics, and politics interfering in conservation," Ellsworth said.

There is no cure for TB and brucellosis, Ellsworth said, and any application would be impractical and far too expensive to administer.

"In short, there is no vaccination out there and even if there were, you'd still have to look at the feasibility of vaccinating a free-roaming herd," he said. "They have done some research in Yellowstone National Park on brucellosis, which is still on-going, but so far there is nothing that looks very promising."

The disease problem is also having an impact on the size of the herd in Wood Buffalo National Park.

"Last year we counted just over 2,200 and there is obviously more than that. Just how many is a little bit of a guess, but probably somewhere in the area of 2,500," said park warden Doug Bergeson.

"It's actually on a slow decline," he said. "We have a major study looking at why, but probably one of the reasons is having the diseases -- TB and brucellosis -- as well as a high wolf population."

"Weak animals will always result in a high wolf population," he added.

Along with the disease and natural predators, Bergeson said the bison also have to contend with man's changes to their range.

"Since the Bennett Dam was put on the Peace River (in the late 1960s), the habitat hasn't had the same cycle of wet and dry years," he said.

The wet and dry areas of the park are critical to survival of the bison during the seasonal extremes, Bergeson said.

"They typically have a winter range and a summer range," he said. "Often, the winter range will be in areas where the range will be wet in the summer and then when it freezes, they utilize all those areas where they can get in to the nice wet areas at the loose edge where they can get access to in the winter months.

"That way, they don't over-utilize one area for resources," he said.


The boundaries of the Bison Control Area (BCA) extend from Trout Lake in the west, north to Fort Providence, and east to the Fort Resolution-Fort Smith junction.

The BCA is monitored during the winter months by Resources, Wildlife and Economic Development, to ensure that diseased bison do not migrate into herds of healthy animals in the Mackenzie and Nahanni regions.

It's a real problem, said Michelle Tanguay, BCA technician for RWED in Fort Smith. During winter months, bison can move with greater ease over the frozen rivers and lakes.

"There are no physical barriers to keep the bison in the Slave River lowlands, so they could potentially move into that area," she said.

While the area is monitored from the air and ground by RWED, Tanguay encourages the public to report any sightings of bison in the area.

"If they see a bison within the control area they should definitely call us or the local RWED office," Tanguay said.

Hunters bagging and tagging a buffalo within the area should report the kill to a wildlife officer.

"If there is a bison killed within the control area we have to go out and perform a necropsy and take samples, but the meat would be utilized if possible."

Ellsworth said they perform the population survey every winter, because the animals are much easier to track in the snow.

"One of the problems is surveying bison in the summertime is ... they're hard to see," Ellsworth said.

The area is monitored from December through to the end of April, he said.

"In the winter time we can follow tracks. We conduct shoreline patrols every week," he said. "We've designed the survey to be carried out through the winter, which is giving you the best opportunity to pick up tracks, any sign or actual sightings of bison."

Expanding the range

Ellsworth said the herds are roaming further west and north as the bison seek new territory and forage.

"We've had reports of sightings at Mosquito Creek, which is 20 kilometres south of Edzo," he said. "That's the farthest Northern sighting we've had."

"They are there, and that represents a sighting, but whether or not that represents a range extension, remains to be seen," he said. "If those animals remain there all year-round with cows and calf groups, then that starts to indicate a whole range extension."

Bulls during the rut will often travel long distances away from the usual range land, he said, so isolated sightings may be nothing more than that.

The public is encouraged to call local wildlife officers or RWED at (867) 872-6439 if they encounter any sign of bison within the BCA.