Wolves preying on boreal woodland caribou are a key reason why this caribou population is listed as threatened under Canada’s Species At Risk Act (SARA). Wolves have much easier access to caribou than they historically have because of linear features, such as abandoned industry seismic lines, that allow the predators to travel more quickly. The ultimate goal is to slow down wolves, and thus protect caribou, by restoring vegetation on the seismic lines. And a recent study shows that revegetation of 50 cm in height or more — some of it naturally occurring — actually starts that restoration process, and slows down wolf movement. This finding will help inform restoration strategies that are increasingly targeted and cost-effective.
The study was funded by the Regional Industry Caribou Collaboration (RICC), which is led by Devon Canada and includes fellow COSIA members Canadian Natural, Cenovus, Imperial, Nexen and Suncor, as well as non-COSIA members Alberta-Pacific Forest Industries, Athabasca Oil Corporation and MEG Energy. For the study, University of Alberta researcher Melanie Dickie captured and fitted about 20 wolves with radio collars. Over a two-year period, these radio collars sent GPS location signals every five minutes, allowing Melanie to closely track the wolves’ locations, movements and speeds.
The wolf-tracking research was complemented by Devon’s advanced 3D LiDAR and vegetation mapping.
“LiDAR gave us really high-resolution imaging of the boreal landscape,” says Amit Saxena, senior technical lead, Wildlife, Biodiversity & Land Stewardship at Devon, and RICC Chair. “Through a detailed vegetation mapping process using the LiDAR, we were able to get a three-dimensional understanding of the vegetation conditions and height, both on the seismic lines and in the adjacent forest.”
The legacy seismic lines under study date back as far as the 1960s and up to the early 2000s. They were cut at that time to allow for conventional resource development and were typically straight and broad — up to eight metres in width. This makes them readily accessible to not only industry and recreational users, but to wolves as well.
By contrast, low-impact seismic lines, which have been the standard since the mid-2000s, are no more than 2.5 metres wide, leave standing trees in place, do not compact the soil, and are sinuous rather than straight. Due to these characteristics, these lines recover naturally by the following growing season in most ecosystems, and wildlife (and human) traffic on them is much less than we see on the legacy lines.
Melanie’s RICC study found wolves travel two-to-three times faster on legacy seismic lines, compared to the natural forest. The distance travelled by wolves increased by up to 54% every hour they spent on these linear features. This would appear to increase their travel efficiency, hunting efficiency and ultimately result in higher kill rates of caribou.
But the study also found that, once vegetation levels on these legacy seismic lines reach as little as 50 cm in height, wolf travel speeds are reduced significantly. The higher the vegetation grows beyond 50 cm, the more wolves slow down, but the critical height that has the greatest impact is 50 cm.
This finding is important for a couple of reasons, explains Amit. First, tree-planting, which remains the most common technique for restoring legacy seismic lines, usually results in vegetation that reaches the critical 50 cm height in as little as two growing seasons if it’s done right and if the right growing conditions exist. Just as significantly, he adds, many of these seismic lines are naturally re-vegetating on their own, to vegetation heights of 50 cm or more. And we are not currently measuring which seismic lines have already achieved this level of vegetation re-growth. On lines where vegetation growth is already naturally occurring, additional tree-planting (which is expensive and time-consuming) may not be immediately required, and restoration efforts can instead be focused in areas where vegetation regrowth is stagnant or not occurring on its own. This approach should have the most impact on reducing wolf travel and movement efficiency.
This is no small discovery. There are over 100,000 km of seismic lines in caribou habitat in Alberta’s Oil Sands Area. With an average estimated restoration cost of $10,000 per km, the question is: where can restoration efforts be most impactful and have the most bang-for-the-buck?
“This study shows that a little vegetation goes a long way,” says Amit. “Going forward, it will allow us to make more informed and strategic decisions. We certainly don’t need to be replanting all legacy seismic lines. We need to target the ones where we can have the most immediate functional impact. That includes lines that are not re-vegetating on their own, either because of natural conditions or due to repeated human use of these lines.”
Informed by this study, RICC has focused on prioritizing restoration areas, conducting trials and monitoring restoration success, both in terms of vegetation re-establishment and wildlife use. This has led to the implementation of restoration treatments on more than 1,000 km of legacy seismic lines by RICC companies in the Cold Lake and ESAR caribou ranges. Continued wildlife-tracking has shown a decrease in wildlife use of treated linear features compared to untreated linear features by most species, including wolves.
Ultimately the study could also point the way towards a new way of defining when, and how, disturbed caribou habitat is considered as recovered. Currently the Federal Recovery Strategy defines disturbed caribou habitat as any human-caused change that is visible using Landsat satellite imagery. Seismic lines fall into this category and, because trees grow slowly, the lines remain visible from space for decades.
However, given the study findings, it may be worth considering when lines revegetate enough to slow wolf movement on them. For example, in the Devon LiDAR study area, 13% of the lines had already reached the 50-cm height threshold, but are still considered “disturbed” using the federal caribou recovery strategy definition.
In the meantime, RICC will continue the important work of determining which lines to restore and how to do so in the most effective way possible.
“What’s important about this collaboration is that so many companies are working together, allowing us to take on township-size restoration projects,” says Amit. “At the end of the day, what caribou need are large areas of undisturbed habitat. We have to find the best ways of providing that while maintaining a viable industry.”