From the Jasper Fitzhugh, December 23, 2010 –
It was the ravens that alerted us. We had been tracking a coyote that crossed our path not long ago with a small hare in its mouth, when we noticed a few ravens hovering several meters away. They made low gravelly squawks at one another like they were sharing a secret.
Their secret: Wolves killed an elk here several days ago. They likely used the large slope above us to run the elk downhill to its demise. Like a forensics specialist, my friend and tracker Jen Wasylyk pieced together clues to the past week’s events. The evidence was spread out over a circular area several metres across, but the flesh of the animal was long gone. What remained was blood-soaked earth, coarse grey-brown hair, and a rumen pile where the stomach was ripped open.
We found the kill site at the back of Whistler’s campground last winter. It may have been the handiwork of the Cavell or Signal wolf pack. We know this because Parks Canada has collected movement data on wolves for several years. Most recently, biologists Layla Neufeld and Mark Bradley have been studying wolf activity in the Cavell area as part of a trial seasonal closure of the Cavell Road. They aim to understand whether roads and trails are allowing wolves to access caribou habitat that was previously more difficult to get to when wolves had to work harder to move through deep snow and forested terrain. The results of their study became public last month.
Wolves are top predators in Jasper National Park, and generally hunt deer, moose, elk, and small mammals to survive. These animals are easy for wolves to hunt because they share habitat in the valley bottoms, kind of like living close to the grocery store. Caribou, on the other hand, tend to select habitats that are harder for predators to access. While this strategy means they are less likely to run into a wolf, the quality of food available in these areas is marginal, and probably contributes to caribou having fewer calves, less often.
“Caribou do best when they are isolated from other prey, and isolated from wolves” says Neufeld. “All caribou isolate themselves somehow – you can see examples across the country. Boreal caribou live in bogs and mountain caribou use deep snow. They try to keep themselves away from other wolf prey.”
However, caribou become a more reasonable food choice for wolves when they are easier to access. Think of how big box stores become worth the drive when you have a four-lane highway with no traffic lights leading you right to them. The biologists are concerned this may be occurring when people pack down snow-covered winter roads and trails that lead up to the alpine. The idea of the closure is to reduce the risk to caribou, although in a natural system risk cannot be removed altogether.
Jasper’s two caribou herds have been in steady decline since the 1960s. Currently the northern herd is estimated to have around 150 animals, while the southern herd is down to around 79 animals spread through the Maligne, Brazeau and Tonquin Valleys. Caribou are considered a threatened species in the mountain national parks and across Canada, and have been altogether lost in some areas. Banff National Park’s population winked out two years ago when the last five animals were killed in an avalanche.
In order to evaluate whether or not wolves are obtaining access to alpine areas using roads and trails, wolves from each pack were equipped with a GPS collar. Location data from the collars were recorded at regular intervals, telling the biologists how fast the wolves were traveling, and on what terrain. Results showed that overall, wolves preferred to travel on packed roads and trails compared with any other terrain. They traveled significantly faster on roads and trails than they did elsewhere. The study also looked specifically at how wolves used the Cavell Road before and after the snow on the road was packed. When the road was packed, wolves were over one and a half times more likely to select the road for travel than when it was not packed. The advantage wolves gain from the increase in speed and ease of travel may increase their predation risk to caribou.
Neufeld and Bradley are quick to point to the value of long-term studies. Factors like snow pack can change wolf behaviour from year to year. In addition, wolf pack dynamics are incredibly variable. For example, last year the Cavell pack consisted of three individuals, two of which were collared for the study. Since then, the uncollared wolf has disappeared, and one of the collared wolves was killed by other wolves. The second collared wolf, “Wolf 120”, appears to be ranging far and wide on her own although she has not completely abandoned her former range. She has traveled as far west as Kinbasket Lake in B.C., and up into the north part of Jasper National Park.
“She appears to have become a loner,” as Bradley puts it.
“Wolves regularly kill each other, die and re-order socially,” Neufeld adds. Both biologists agree that because there are so many factors that can change between years, conducting the study over a number of years is necessary to pick up trends.
Predator access is not the only threat Jasper caribou may be facing. Changing habitat, vehicle collisions, and small population sizes may be having an impact as well. Parks Canada will continue to monitor caribou and wolves to further identify threats and look for ways to take the pressure off what’s left of dwindling herd sizes.
Now that the Cavell pack has disbanded, Bradley wonders if it will be the Sunwapta or Signal pack that takes over their territory. On the Friday before this article was published, Neufeld detected the Sunwapta and Signal wolves all within five kilometers of each other. Wolf 120 was also there.
“Who knows what might have been happening down by Buffalo Prairie today!” says Neufeld. Perhaps the snarling re-structuring of packs, a small turf war, shifting allegiances. It sounds like a mafia movie, except that collars on individuals of both packs might let us all in on the new order of things. Stay tuned.