Sharing the Land with Grizzly Bears
Sow grizzly with her cub© Terry Willis
As protected areas, the mountain national parks make a significant contribution to grizzly bear conservation in the Rocky Mountain ecosystem. But the mountain parks alone cannot sustain grizzly bears. Instead they help anchor conservation efforts in the broader landscape by providing a core area where ecological integrity has priority for land use planning.
Because the Bow Valley watershed is one of the most developed la ndscapes in North America where grizzly bears still persist, this area could be a tipping point for the regional population. Populations that once ranged well across the plains and down to Mexico are long gone. The species is vulnerable to further loss for a number of reasons.
Bears and the mountain parks
Grizzly bears reproduce slowly, require large home ranges and are thinly dispersed across the landscape. This makes the species particularly sensitive to human activities or natural events. From 1996-2001, Alberta’s human population rose just over 10 percent. The Calgary - Edmonton corridor is now one of four major urban centres in Canada. This means human activity is rapidly increasing along the eastern edge of the grizzly bear’s current range. It’s becoming harder for grizzlies to avoid people. Yet to survive, they need to be able to do just this.
Canada’s mountain national parks can contribute refuge in the greater landscape. But this requires special considerations for how we share this landscape with bears. Hosting three million visitors annually, and supporting two communities, Banff National Park exemplifies the challenges ahead.
Approximately 60 grizzly bears live in the park. About 16 of these are adult females. Along with the middle Spray Valley and an area known as Flint’s Park, the Lake Louise area supports a concentration of reproductive female bears. These females and their offspring represent the birth side of the population equation. To balance deaths and sustain the local population, adult females must successfully raise cubs that will also survive and reproduce.
This takes time. Female grizzly bears in the Bow River watershed have the lowest reproductive rate of any studied grizzly bear population in North America. On average, they don’t reproduce until seven years of age, and then have only one to two cubs every four to five years. This means the population has low resilience to “bounce back” from an increase in mortality or a decrease in the birth rate.
Concentrations of Female Grizzlies in Banff National Park© Parks CanadaClick here to view a larger version of this map (94 KB).(This image is larger than 450 pixels)Printable Version (PDF, 97 KB)
Until the early 1980s, grizzly bears suffered high human-caused mortality in the mountain national parks largely due to poor garbage management practices. In the Lake Louise area, a particularly high number were destroyed or relocated. Recently the local population has begun to rebound from this high mortality; but this population growth is slow and vulnerable to changes in birth and death rates. In light of this and the fact that the Lake Louise area hosts approximately 1.4 million visitors a year, management must continue to err on the side of caution.
Based on recommendations from the Banff-Bow Valley Study, the 1997 Banff Management Plan set targets to improve effective habitat (safe access to quality habitat) and to reduce annual human-caused grizzly bear mortality to one percent or less of the park population; this translates to less than one bear per year. Due to road and rail mortalities we currently exceed this target.
What Bears Need
Like all species, bears need habitat that provides for their daily and seasonal needs. Within their home ranges, grizzly bears seek out seasonal foods, mates, den sites, travel routes, and nurture and raise cubs; they make choices to survive. These choices have become complicated by how we use the landscape they rely upon.
Lake Louise townsite area© Parks Canada/W. Tucker
Suitable and secure habitat is patchy and of medium to low quality for bears in the park’s mountainous landscape. The rugged terrain naturally fragments habitat and dictates how bears can travel through it from one habitat patch to another. The best, most continuous habitat for bears and other wildlife is along major valley floors like the Bow.
In the Lake Louise area, bears have run low on options to avoid people. As they seek their life requirements, bears must cope with the busy Trans-Canada Highway, the Canadian Pacific rail line, the hamlet of Lake Louise, the Bow Valley Parkway, the Icefield Parkway, busy trails and backcountry campgrounds, summer use on the ski hill, and several outlying commercial accommodations. Together, these developments fragment the habitat into patches of varying sizes, exposing bears to encounters with human activity.
How we affect bears
Human activity can affect grizzly bears in three ways:
- Bears are displaced from important habitat
- Bears begin to tolerate people or become habituated
- Bears have an increased chance of being killed on the highway or railway
Generally grizzly bears are wary and try to avoid people. Near a busy trail in good habitat, they may do this by feeding early or late in the day. With constant human disturbance, they may be forced to rely on poorer quality habitat, causing them to expend more energy to find food - energy they need to conserve and store as fat to successfully hibernate and reproduce.
Alternatively with repeated exposure to the sights, sounds and smells of people, some bears lose their wariness of people. They become habituated. Young bears, being at the bottom of the social ladder and on a learning curve, are willing to take risks. They may learn to tolerate people to access natural foods growing in and around developments. Sows with cubs may also choose habitat close to people as a way to avoid adult male bears that may pose a risk to their cubs.
Such bears are more likely to enter townsites and campgrounds where they may get into carelessly stored garbage or food. Bears that associate people, vehicles or facilities with food are usually destroyed. Since habituated bears spend more time near the railway and roads, they are also more likely to be struck and killed on them. Research in Yellowstone National Park indicates that habituated bears are three times more likely to die a human-caused death.
Mortality on roads and rails
In the Lake Louise area, traffic volume has increased 40% on the Trans-Canada Highway in the last ten years. It is expected to increase at a rate of two percent per year. Nearby, the CP mainline carries up to 37 freight trains daily through Banff and Yoho National Parks.
Though wary bears typically avoid busy developments, at times they must attempt to cross roads and the railway to seek out seasonal foods or mates. Paradoxically, some bears regularly travel the railway to forage on an artificial attractant - grain leaked from faulty grain cars. While some bears may not even attempt to cross the high volume highway, those that do are more likely to be struck and killed on it or the rail line.
Together, incremental mortality and barriers to movement may result in wildlife populations that become smaller and isolated over time. Such populations are at greater risk of local extinction due to in-breeding and an inability to recover from disease, changes in habitat, or direct mortality.
Sharing the land
To live long lives, grizzly bears need to be able to access habitat without constantly bumping into people. Wary bear behaviour can best be maintained and passed on to cubs by ensuring female grizzly bears have secure areas. Secure areas give bears enough space to forage in their home ranges on a daily basis without being disturbed by people.
Grizzly bears also need quality habitat. Past fire suppression practices have resulted in older, dense forests with limited bear foods replacing open forest and meadow habitats. This build-up of woody fuel has also increased the risk of uncontrollable wildfire to park facilities and communities. Fire is being reintroduced in the park. This will provide grizzly bears with more habitat options in the future.
Finally, to meet their basic needs, bears must also be able to safely move through the landscape. Secure wildlife habitat linkages or movement corridors between areas within and beyond a bear’s home range need to be maintained. Male grizzly bears typically travel greater distances, and establish larger home ranges than females. Such movement helps ‘mix up’ the gene pool to prevent in-breeding.
Wildlife movement corridors in the Lake Louise area need to tie into regional and even continental movement corridors. Most of the park’s estimated 60 grizzlies have home ranges that cross into other land management jurisdictions. For this reason, Parks Canada is working with neighboring land use managers to coordinate conservation efforts.
We have the ability and responsibility to consider the effects of our actions on other species. Based on the best information available, a number of bear related management actions are underway in Banff and other national parks. Our goal is to increase both human and bear safety, and thus ensure bears continue to enrich our community of life, as well as our imagination.
Wildlife Corridors in the Lake Louise area© Parks CanadaClick here to view a larger version of this map (121 KB).
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More information on bear management
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