Caribou projects to help boost herds
Thursday, Oct 16, 2014 06:00 am
A series of projects focused on bolstering the dwindling number of woodland caribou in Alberta and B.C. appear to be providing both dramatic results and some optimism about the future of caribou in Western Canada.
Boreal woodland caribou are classified as threatened in Canada, as is the southern mountain caribou population that is found across the mountain national parks of Alberta and B.C.
Caribou numbers in both provinces are in rapid decline, primarily because of increased predation, which is a result of habitat fragmentation and human use in caribou habitat. Roads, logging and fires open new territory to deer, moose and elk and, as wolves follow their prey into these areas, they discover and prey upon caribou.
Two B.C. projects, one near Revelstoke and the other in northern B.C. near Fort St. John, are using maternity pens where pregnant female caribou can give birth and raise their calves without fear of predation from wolves and black bears.
The calves and their mothers are released in summer when the calves are more able to avoid predators.
South of Fort McMurray, meanwhile, an experimental caribou recovery project led by Nexen Energy on behalf of Canada’s Oil Sands Innovation Alliance is underway testing a predator exclosure: a large, fenced area designed to keep predators out.
“It’s an attempt to test different fencing designs and maybe, and I stress maybe, apply it on not just a five to 10 hectare scale, but on hundreds and hundreds of square kilometers and keep predators out of a big area,” Rob Serrouya, who leads the Alberta Biodiversity Monitoring Institute’s Caribou Monitoring Unit, which is advising all three projects.
“The difference is you don’t have to import caribou and you don’t have to keep exporting them, cows and calves, and handling them all the time. You just create a large area that is free of predators. The goal in both cases is you don’t have to do direct predator removals,” he said.
The 2.5-metre-high fence that encircles the one-hectare test site is a typical page-wire fence found along the Trans-Canada Highway throughout the Bow Valley region. The difference in the exclosure fence design is that smooth sheet metal has been attached along the top of the fence to keep black bears from climbing the fence. A metre-long skirt stretches out along the ground from the bottom of the fence to discourage predators from digging.
“We had to give predators some motivation for trying to get inside,” said Kris Geekie, vice-president, community consultation and regulatory affairs with Nexen, which is leading the project. “We’ve set a moose carcass within the enclosure, which is very attractive to wolves and bears, so they’ll try to get into the enclosure. If predators find a way to get inside, that will reveal a weakness in the fence design, which we can then improve.”
So far, the exclosure design is proving sound. Serrouya said a black bear has been the only predator to find a way into the baited pen by lifting the skirt, which has since been reinforced. Cameras have been mounted both outside and inside the exclosure.
The black bear was able to get out of the pen on its on, but Geekie noted that a gate in the test pen can be opened to release any animal that gets in, but cannot get out again.
The next step, once an effective fence design is achieved, is to decide how large an enclosure is needed and how many caribou the fenced-off area could sustain. The goal behind the exclosure fencing trial is to increase caribou survival rates by decreasing predation, providing a population of caribou some stability over the long term and in the process allow a herd’s numbers to increase.
The maternal pens, meanwhile, work along a similar line by giving calves time to get their legs under them and grow to a stage where they are no longer easy prey for bears and wolves.
Caribou calves born in the Revelstoke and the Klinse-Za maternal pens are already showing a higher than average survival rate, compared to wild-born calves.
The Revelstoke pen, which saw its first season of use this spring and summer, has seen a 100 per cent calf-survival rate; a number unheard of in the wild.
Nine pregnant cows from the Columbia North herd, located in the Mount Revelstoke-Glacier national parks region, were captured in March. The cows gave birth in the pen and the nine calves were fitted with radio collars. The mothers and their calves were released back into the wild on July 23.
“The survival of the animals, especially the calves that still have collars on them, is 100 per cent and they’re already three, four months old. That’s double what the wild calf survival would be. That is the main message: Out of these nine calves that we released, more than half of them would be dead already if it was a wild situation,” Serrouya said.
Before maternity pens can be used, however, he said a caribou population has to be stable and the only way to stabilize a herd and keep it from declining is to solve the larger issues, specifically habitat loss and predation control, which in effect the large-scale exclosure could provide by keeping predators and their preferred prey from a specific region.
In Revelstoke, stabilizing caribou herds first meant setting aside caribou habitat, closing those areas to vehicles, in this case snowmobiles, and reducing the number of predators in the region by reducing their primary food source: moose and deer.
“It follows on the backdrop of other major recovery efforts,” he said, “protecting over 100,000 acres of big, old growth forest of huge cedar trees that are 500 years old. It follows on the back of snowmobile closures and an attempt to reduce moose to indirectly put predator numbers back to historic levels, both moose and predators.
“That seems to have helped stabilize the biggest herd around Revelstoke and so the best thing we’ve achieved so far is stability. We’re hoping this approach, this maternal penning, can now help stimulate growth. From decline to stability and then reversing the trend.”
Currently, the Columbia North herd has about 130 caribou while the Columbia South herd, which stood at about 120 animals in the mid-1990s, stands at six.
“Of course, it would be no surprise if they get wiped out in one event like Banff did,” Serrouya said.
The Revelstoke maternal pen focuses on the Columbia North herd, as it is much larger and stable and, as Serrouya pointed out, it helps the herd that has a chance of surviving.
As the Columbia North herd grows, it is hoped caribou will disperse and join the southern herd.
“It’s very early on, but so far there’s a lot of reason for optimism,” he said.