What’s furry, fierce and likes to dine on porcupine? It’s the fisher, Pekania pennanti, a member of the weasel family that is seldom seen in the wild, but is an important part of British Columbia’s carnivore community. Despite its name, fishers do not fish and are dependent on forests for all their life history needs. The fisher is blue-listed (threatened) in BC, largely due to habitat loss. Female fishers require large diameter trees with cavities to birth and raise their young. They will only use cavities with entrance holes that are approximately 8 – 12 cm in diameter: large enough for them to squeeze into, but small enough to keep larger predators away from their kits. Den trees also need to have other trees and shrubs around them to allow the female approach her den unseen. These specific requirements (along with the fact that females usually require multiple cavities to accommodate the growing kits) make fisher populations extremely vulnerable to extirpation through loss of suitable denning habitat.

In the Bridge River Watershed, north of Lillooet, BC, fisher habitat has been impacted by the creation of two large hydro-electric reservoirs, large-scale fires, mountain pine beetle, and an ongoing history of forest harvesting that is dominated by clear-cut systems. Understandably, there is concern about the combination of these habitat impacts on local fisher populations.

The Habitat Conservation Trust Foundation and BC Hydro funded a three-year project that would provide an accurate population estimate for fishers in the Bridge River watershed, as well as estimate the distribution, abundance, and supply of potential reproductive dens. In-kind support for this research was provided by the Lillooet Tribal Council, BC Ministry of Environment, and the BC Trappers Association.

Estimating Fisher Density

Fisher expert Larry Davis and his research team determined fisher density estimates using a winter hair snag survey. Davis explains: “We used sticky mousetrap paper to pull a sample of hairs from fishers that were attracted to traps baited with a chicken wing. Fishers trying to get the wing would press against the mousetrap paper and leave a hair sample behind for us to collect. We sent the samples to a laboratory specializing in wildlife genetics that identified the samples by species, sex, and individual identity.”

“Of course, we captured many other animals that went after the bait,” Davis continues. “We even had one wolverine chew the top half of the trap off.”

In the end, Davis and his team were able to identify 8 different fishers from the data, some of which were captured multiple times. The data was inputted into a computer program that used this information to estimate that there were 14 fishers in the 771-km² study area. This yields an estimate of 18 fishers per 1000 km²: relatively abundant when compared to estimates from elsewhere in BC.

“It’s important to note that this estimate is based on only one season of sampling and animal numbers can vary considerably between years,” clarifies Davis. “Also, only three of the 8 fishers sampled were females and some are likely to be young from last year’s litter or transient animals. Despite this caveat, Davis believes that “the Bridge River area supports a healthy population of fishers, and that a sustainable population can be maintained if important habitats, such as den sites, are retained in managed forests”

Estimating Available Denning Sites

To estimate the number of trees that would make suitable fisher den sites, Davis concentrated on areas where track transects had found fisher. Potential fisher den trees were identified as those meeting the following criteria:

• right species;
• large diameter stems; and
• the presence of a heart-rot decay cavity with an entrance hole 8 – 12 cm in size.

The “right species” criterion was based on previous research that found fishers using cottonwood, balsam poplar, trembling aspen, Douglas-fir, and lodgepole pine as den trees in BC. Common to these tree species is that they can have extensive heart-rot forming large internal cavities while the tree is still living. Other trees, such as spruce, also get heart-rot, but don’t maintain the hard exterior shell that preserves the standing tree and cavity for many years. The minimum tree diameter depends on the tree type, but is generally large for the particular tree species.

Davis and his team estimated the number of potential trees in the landscape by counting the number found in 1 hectare transects distributed across the study area.

“It turns out that trees meeting all our criteria are rare in the landscape,” says Davis. “Even in the ‘best’ habitat, there was less than 1 tree in 2 ha, and most forest types had much lower densities of potential den trees.” As Larry explains, the actual densities may be even lower still: “There is one additional criterion a fisher would have that we couldn’t easily check – the size of internal cavities. Cavities large enough for a female fisher and her kits are estimated at 25 – 30 cm in diameter, based on the size of an average female and internal measurements we have taken at fisher dens. Given this, fisher reproductive dens are likely to be much scarcer than we think, but our estimate provides a starting place for making recommendations to forest companies on targets for protecting fisher den trees.”

So how are these findings being used to inform fisher management? These results, combined with the findings of more than 20 years of fisher research in BC, have been used to create management recommendations and targets for fisher habitat. Davis and his colleagues have created a website summarizing this information at www.bcfisherhabitat.ca . For foresters and government, the website supplies targets on the amount of area and number of structures fishers need for breeding, resting, foraging, and movement habitats. This means tenure holders, such as trappers, can use this information to ask foresters how they are meeting fisher targets for logging operations on their trap lines.

“Fishers are a blue-listed species in BC, and forest professionals are legally required to manage landscapes to help maintain this species,” says Davis. “The website allows the BC Fisher Working Group an opportunity to continue working with trappers, government, the forest industry, and others to update and refine management strategies for fisher in a timely fashion.” Davis and his team have also created resources to encourage private landowners to preserve suitable den trees on their land (view). “Preserving these types of trees not only help fishers, it also benefits around many other native species reliant on them for their continued survival.”

Many thanks to Larry Davis for supplying much of the information and images for this article. In recognition of the fact that studies like this one indicate suitable fisher denning habitats are becoming increasingly rare, HCTF is currently funding a project to determine if artificial den boxes will be used by reproductive fishers, and the extent to which these devices might mitigate the loss of natural denning habitat. Check back here for future updates on this project.

View updates about this project>>

In the frozen wilderness of North-central BC, a small, furry head pops out from under the snow. Its fox-like profile stands out against a creamy orange bib of fur. In a flash, the animal’s long, lithe body and bushy tail spring from the powder. It is an American Marten (Martes americana), a medium-sized mustelid known for its tree-top acrobatics and cat-like curiousity. She boldly lopes across the snow towards a tasty morsel, conspicuously placed to entice her into a cage trap disguised with branches and straw. Marten are commonly trapped for their pelts, but this cage won’t spell her demise. Instead, she will become part of a ground-breaking study examining marten’s movements, and how they might be affected by forestry practices.

Shannon Crowley, a researcher with the John Prince Research Forest (co-managed by UNBC and T’laz’ten Nation), and his colleagues check the study traps daily: if they’re lucky enough to get a marten, they fit it with the latest in GPS collars before releasing it safely back into the forest.

“They’re tough little critters,” confides Crowley. “Based on our experiences capturing them, they’re not fearful at all. We’ve had marten in cage traps that we’ve released, only to have them come back moments later to steal a piece of bait sitting right next to us.”

Crowley and his colleagues are working on their second year of an HCTF-funded project to determine how marten populations are affected by salvage logging of Mountain Pine Beetle-ravaged stands. They are comparing the species’ use of logged and unlogged areas by remotely tracking the movements of their collared subjects.

“We’re working with very new technology,” explains Crowley. “Really, this study is pioneering the use of GPS collars light enough to go on an animal this size. To my knowledge, we and a group in Scotland are the only ones to have tried them on marten.”

The general rule of thumb for tracking collars is that they shouldn’t exceed 5% of an animal’s body weight. The collars used by Crowley and his team are below that threshold, sitting at around 3%.

“The marten really don’t seem to be bothered by them,” says Crowley. “We happened to get a video of one of the collared animals at one of our remote camera sites, and he was heading up into the trees, behaving very much like a typical marten.”

Above: Video showing typical marten behaviour. These curious creatures often travel under the snowpack, but are equally adept at climbing trees. See more videos of marten and other mesocarnivores filmed in the John Prince Research Forest at the end of this post.

Crowley says the location data from the new GPS collars is a significant improvement over what they could previously obtain using radio units.

“We’re pretty impressed: we’re getting the kind of movement data that we could have never gotten in the past,” says Crowley. “Getting a location used to be very labour intensive, especially in harsh winter conditions. We would typically get about three locations a week. Now, we’re averaging between six and twelve locations a day.”

The increased amounts of data allow Crowley and his team to examine how marten are moving across the landscape at a much finer scale. “Previously, we could see where they were, but we couldn’t see how they got there. Now, we have a clearer picture of how they’re using different habitat types.”

Crowley’s team has been working closely with local forest company Conifex to compare martens’ response to different logging practices. Eventually, their results could be used to inform forest management decisions so as to reduce the impact on marten, as well as other species.

“Marten have proven to be really good indicators of ecosystem health,” emphasizes Crowley. “They’re generally associated with mature forests with lots of structural complexity, which are also important for animals such as woodpeckers and mule deer.”

Though Crowley’s marten study is a short-term project, the data collected will become an important component of a long-term monitoring program focused on mesocarnivores, a group that also includes fishers, river otters, foxes and Canada lynx.

“The mesocarnivores encompass a diversity of species that require different habitat types,” explains Crowley. “Studying one species alone can tell you something, but when you look at a bunch of them together, by inventorying and surveying in different habitats, they can give you a much better idea of what’s happening on the landscape.”

This level of understanding is particularly important when considering the rapid rate of environmental change associated with salvage logging. Though marten populations as a whole are thought to be stable in BC, they have become endangered or even extirpated from other jurisdictions through habitat loss.

“Research like this is really about taking preventative action, so that marten don’t become endangered in BC as a result of land use practices.” Crowley states.

Despite the economic pressures to maximize timber harvest, Crowley remains optimistic about the potential for this research to make a positive difference for habitat conservation. “Within the forestry industry, I think there’s definitely an appetite for finding ways to reduce impacts. Wildlife and habitat have definitely become part of the conversation, though we still have a long way to go before wildlife values are incorporated as a standard practice.”

The John Prince Research Forest is the largest research forest in North America, more than 32 times the size of Vancouver’s Stanley Park. Situated 50 km north of Fort St. James, the JPRF lies between Lakes Chuzghun (Tezzeron) and Tesgha (Pinchi)in traditional Tl’azt’en territory and provides research opportunities for UNBC staff and students and education and employment opportunities for the local community. Check out some of the other amazing wildlife footage captured by remote cameras in the forest (submitted to us by Shannon Crowley):

American Marten:

Canada Lynx:

Wolverine:

Each spring, BC’s fire crews brace themselves for the intensity of the fire season ahead. At the time of writing, 2014 was on track to become a record year. Since the beginning of the season in April, more than 330,000 hectares had burned, only ~8,000 HA shy of the 30 year record. News coverage of evacuations and threats to human infrastructure have shaped our perception of forest fires. We think of them as catastrophic forces of destruction: unpredictable disasters to be suppressed or extinguished at all costs.

There is, however, another side to forest fires, one that would suggest this year’s increased fire activity – if kept away from human settlement and infrastructure – is actually beneficial. Ecologists have confirmed empirically what First Nations have known and practiced for centuries: fire is as much a force for renewal as it is of destruction.

After a forest fire, what appears as scorched wasteland is actually an ecosystem ready to begin anew. Under the charred earth, roots and seeds lie waiting to capitalize on the nutrients provided by the ashes of their predecessors. Sunlight, once scarce under the thick canopy of mature trees, now reaches the ground, allowing grasses and berry-producing shrubs to flourish. Burned trees still standing provide habitat for many species of insects and birds. Fire is nature’s own highly effective method of ecological restoration.

We live in a province shaped by fire; the plants and associated animals found in a particular location are a product of that area’s fire regime. Before the introduction of modern fire-suppression techniques, scientists estimate that around 500,000 hectares of forest burned in BC each year, a figure that dwarfs the sum of even the most prolific fire seasons of recent years. Just as fire shaped BC’s landscape, an absence of fire is shifting it again. In the many areas where the natural fire cycle has been interrupted, trees have invaded grasslands, forcing wildlife to look elsewhere for forage. Fuel, in the form of dead wood and debris, has built up on forest floors, creating the potential for more intense, more dangerous fire events than would have occurred under the natural fire regime. Perhaps one of the most graphic unintended consequences of fire suppression is the Mountain Pine Beetle epidemic. Historically, areas of pine forests would have burned down and regenerated roughly once every 100 years, resulting in multi-aged forests that were more resistant to insects and disease. Modern fire suppression has led to vast, interconnected stands of old pines- a favourite food of the beetle. Add to this increased temperatures that allow the beetle to survive through the winter, and you have the worst insect epidemic in BC’s history.

Jordy McAuley has witnessed first-hand the effects of fire suppression on lands where burning was once an integral part of the forest lifecycle. His outfitting territory in the Williston area of BC includes large stands of mature aspen and pine-beetle affected forest. The encroachment of trees on previously open areas, combined with flooding caused by the creation of the Williston reservoir, has severely reduced the amount of winter range available for ungulates such as moose. They have begun to travel beyond their traditional range to higher elevations. With them come the wolves, and that’s bad news for the caribou who overwinter there.

“The caribou are easy targets… they’re really struggling,” says McAuley. “If we can improve range conditions for moose and other ungulates at elevations lower than where the caribou are, it would hopefully lure the predators away and give them a chance.”

Since purchasing the territory nine years ago, McAuley has been keen to bring fire back to the landscape after witnessing the improvements to range conditions following prescribed burns in other regions.

“Once you burn, everything comes back new,” McAuley says. “The canopy opens up, and there’s this rejuvenation of forage for all kinds of wildlife. Moose do well, same with elk and goats. The berries come back, providing food for bears – even birds seem to benefit.”

McAuley’s observations are consistent with research showing increased species use of habitats after burning. Properly executed, prescribed burns create a mosaic of habitat types that can support an increased number of species, and provide the resources necessary to sustain their populations. Indeed, the broad scale restorative properties of prescribed burning make it an attractive land management tool, but conducting burns is expensive, and some of the Province’s burn programs are reliant on external funding. Using hunting licence surcharge revenue, the Habitat Conservation Trust Foundation (HCTF) has supported prescribed fire projects, such as the Peace-Liard Burns, for thirty years. In 2014-15, the Foundation invested over $350K in prescribed burning programs across BC, including McAuley’s moose habitat enhancement project.

With funding for his project secured, McAuley began working with a team of biologists on the burn planning and consultation process. In an era of multiple (and often competing) uses on the landscape, accommodating the perspectives of all stakeholders can be a difficult task. It’s a delicate balancing act between protecting everyone’s interests and still accomplishing an effective burn. Biologist and Wildlife Infometrics’ staff member Stephanie Rooke agrees that the burn approval process can be daunting.

“There are many, many factors to consider, and some real constraints on what we’re able to do,” says Rooke. “Often, the lands we’re working on are next to forestry plantations, and there are First Nations communities nearby… safety is always our number one concern. We can’t afford to lose a fire.”

Rooke says there are a number of precautions that are used to make sure that burns stay in control and away from human settlements. “The Wildfire Management Branch has indices that we use to determine when it is safe to burn: factors such as temperature, moisture, and relative humidity all have to line up before we’ll start a fire. But our biggest control mechanism for spring burns is high-elevation snow load: because we’re burning uphill, we try to have the edge of where we want burned bordered by snowpack.”

Despite challenges in the planning process and narrow windows for burns, the project team persevered and managed to get their first burn done this May. McAuley was on site for the big event, excited to finally see his idea become reality.

“It was such a big build up: in the beginning, it was like running into walls. I’d tell people what I wanted to do, but with all the merchantable timber up here, they’d say it can’t be done. But I just kept pecking away, and found some folks that knew the benefits of fire on the land,” recounts McAuley. “To see that helicopter show up, ready to go… well, it was pretty exciting to see that smoke start coming out of the bush”

Over the next few years, the project team will monitor this and other planned burn sites to determine what effect fire has had on forage availability and use by ungulates.

“Our hope is that the herbaceous plants and shrubs that recolonize burned areas really make a difference for moose populations in the area,” says Rooke. “Shrubs are particularly important in winter, when the deep snow makes it difficult for moose to access other forage.”

If the project proves a success, the team is hopeful they can share their experiences with others interested in using fire to enhance range conditions.

“There was a steep learning curve for everyone, but now that we’ve done it, I think there’s the potential for others to follow in our footsteps, and maybe initiate their own projects,” encourages McAuley. “I think getting fire back on the land, when done properly, has the potential to benefit everyone.”

In addition to HCTF funding, this project also received financial support from the Peace/Williston Fish and Wildlife Compensation Program. For more information on projects made possible by angling, hunting, guiding and trapping licence surcharges, click here.