On the map of Riding Mountain National Park’s three TB-management zones, lies a black amoeba-shaped blob.
Straight south of Grandview, the irregular-shaped area in the Western Control Zone was created by drawing circles with a six-kilometre radius based on the known home ranges of radio-collared elk that have tested postive for bovine TB under the Parks Canada program between 2005 and 2009.
“That’s what we are calling the core area of disease. That is based solely on recent TB positives,” said Ken Kingdon, wildlife health program project co-ordinator at RMNP, during a tour organized for local media.
Research shows that a cow elk seldom travels outside of the 78-square-kilometre zone where it was born. Bulls range slightly further, about 126 sq km, and white-tail deer, about 15 sq km.
Also inside the blob is a pink circle which indicates a TB-positive case found in domestic cattle just outside the park’s northern boundary.
A single black circle can be found in the buffer zone outside RMNP’s extreme eastern tip south of Kelwood in the Rural Municipality of Rosedale. That’s where TB turned up in the whitetail deer surveillance program last fall.
“This has implications for the CFIA, as well as us,” said Kingdon. “Our assumption up until this date was based on the fact that we had not found any TB-positive animals outside of this Western Control Zone since about 2001.”
But in 2003, a small cattle farm with about eight head was found to have a single TB-positive cow right where the two-year-old deer was later found.
“Prior to that, we had thought that the east side was at a low risk for disease. This animal changes that a little bit,” he said.
Dr. Bob Keffen, a CFIA vet, said that immediately after the deer was found, all the cattle
“It’s a disease that you can’t just chew away at. You have to go in there and get the job done.”
– DR. BOB KEFFEN
within a one-mile radius were tested and all came up negative for TB.
Because the infected deer and cattle shared the same quarter section, TB may be endemic in deer in that area but at a very low level, said Kingdon.
“There’s very few elk down there, so again, the question is whether this is a deer issue rather than an elk issue and what does that mean?” he added. “We are kind of feeling our way through it.”
In the meantime, various strategies are being discussed. Since deer are Manitoba Conservation’s jurisdiction, more hunters may be encouraged to submit carcass samples. Parks Canada, for its part, may begin blood testing elk there. The CFIA may step up testing of cattle in the area.
Looking back over previous decades, TB-positive cases have ranged far and wide. For example, positives have been found in elk and deer in the R. M. of Rossburn, two elk south of Onanole, two wolves near Whitewater Lake in 1978, and an elk near Lake Audy.
“Since 2002-03, we haven’t found it outside of the core area – except for this one last fall despite the fact that our surveillance and sampling has actually increased,” said Kingdon.
So why didn’t Parks Canada go in and eradicate the 300 elk and an undetermined number of deer in the so-called TB hot zone a decade ago, especially now that an apparent “burning ember” that may indicate leakage from the containment area has been spotted on the eastern edge of the park?
“Ten years ago we thought the problem was much worse. Ten years ago we had a distribution of disease all the way up to (Duck Mountain Provincial Park) as well,” he said.
Kingdon said that the fact that the disease has been more or less confined to one area shows that combined strategies based on the “shared feed” theory for limiting TB contagion between and among species, such as hay barriers and a ban on baiting and feeding, have been successful in halting the spread by limiting interactions between elk, deer and cattle.
Also, since elk are herd animals, unlike moose, which are mainly solitary, overpopulation may have been behind the spread of TB in earlier decades.
The elk population was slashed by over half since the peak of 5,000 animals a decade ago down to roughly 2,000 in the entire park at present, mainly by doubled hunter tag limits since then and ongoing capture, testing and culling under the Parks Canada program.
In 2001, some 800 animals were taken out by licensed hunters after a hard winter drove many animals out of the park. Hunting currently accounts for about 50 to 100 elk per year.
“It may explain why we saw the disease spread widely in 2000, and now it’s confined to that core area,” said Kingdon. “I don’t want to say it is, because we have no evidence, but it might be one of the keys.”
If the lifespan of an elk is 19 to 20 years for cows, and about 10 years for bulls, some older animals left over from the population peak may be the ones continuing to harbour the disease, and possibly spreading it to deer.
“Is it now time to begin discussing full eradication of wildlife? If we are serious about getting rid of the disease, because it’s so slow growing and insidious, and we don’t have the tools to separate TB-positive and non-positive animals, the safest and most economical way would be to just go in and kill those 300 to 350 animals,” said Kingdon. “Do it quickly, get it over with and then let the system rebuild.”
In Keffen’s personal opinion, as a vet with experience dealing with disease in African wildlife, the best solution would be to go in “hard and fast” with a cull of all the animals in the problem area.
“It’s a disease that you can’t just chew away at. You have to go in there and get the job done,” said Keffen.
But Kingdon said the problem may already be going away. He noted that there have been no recorded cases of TB-positive elk that were born after 2003. In his view, continuing with an accelerated capture and testing program would be best, but he noted that it would be more costly – at roughly $800 per helicopter capture – than a quick cull.
“If we are right, and it’s only old animals, the issue will take care of itself,” he said, noting that radio-collared elk have never moved across Hwy. 10 to the east side of the park. Three collared white-tail deer, however, have been recorded crossing the [email protected]