The ongoing contraction of grizzly bear range in North America began about 300 years ago, when European fur traders, explorers and settlers began exploring what would become the Canadian and American West.
Before Europeans first settled North America, an estimated 50,000 to 100,000 grizzly bears (Ursus arctos horribilis) inhabited the continent. Highly adaptable, grizzlies thrived in many habitats, from the Great Plains to the Arctic.
First Nations revered the grizzly; many believed it was a close relative. Many Aboriginal cultures referred to it as “Real Bear,” to differentiate it from the more diminutive black bear (Ursus americanus). It was also considered to be the “supreme physician of the woods.” To relieve a cold, the Cheyenne drank tea made from yarrow, which they knew grizzlies ate when they could. The Haida in B.C. still refer to the Great Bear as “Elder Kinsman.”
(Photo Credit: Nathan DeBruyn)
In contrast, the relationship between grizzlies and the descendants of Europeans evolved into a kind of warfare, as cattle herding expanded westward across the Prairies. Thanks to ranchers’ and hunters’ traps and rifles, by 1920, grizzly bears were gone from 53 per cent of their original range.
Grizzly populations were fragmented into small, isolated subpopulations occupying mountainous and inaccessible places – islands of grizzly bear habitat surrounded by a sea of agricultural, urban and industrial development. This “islandization” caused human-bear conflicts and prevented bears from moving around and spreading their genes. Over time, more bears died every year than were born or could immigrate.
In the U.S., grizzly populations plummeted through the 20th century, until only 1,000 animals remained on two per cent of their historic range.
The history of contraction and elimination in Canada is less well-known, but the process was the same, eliminating grizzly bears from the Great Plains and parklands east of the Rocky Mountains. And it continues to this day; only small, isolated and/or highly threatened populations exist in western Alberta and most of southern BC, one of which may have disappeared altogether
. Unless these island populations are allowed to grow and/or connect to larger populations nearby, their “slow extinction is all but ensured” (COSEWIC 2002).
Most biologists believe that grizzly bears are an essential part of healthy, fully functioning ecosystems in western North America
. This makes the grizzly bear an indicator species, indicative of both ecosystem health and sustainable development. In other words, where grizzlies thrive, ecosystems are relatively healthy.
Grizzlies are also “ecosystem engineers” that help regulate prey species such as elk and deer. They help maintain plant and forest health by dispersing plant seeds and aerating the soil as they dig for roots and ground squirrels.
Their large home ranges and significant habitat needs makes grizzlies an “umbrella” species; where they thrive, you’ll find healthy fish populations and aquatic ecosystems, and clean and abundant supplies of water for downstream users.
However, history has proven that grizzlies can’t survive where humans are plentiful. Because they have low reproductive rates and are slow at dispersing, they are highly susceptible to population decline. Even small numbers of human-caused grizzly bear mortalities can have big effects on a population.
Likewise, at-risk grizzly bear populations take a long time to recover even after they have been protected. Even under the best conditions, the natural growth rate of grizzly bear populations rarely exceeds eight per cent per year, and it’s usually much lower. Minimizing human-caused mortality, especially of females, is the key to grizzly bear management and recovery.
Human-caused mortality is the greatest source of mortality for grizzly bears and the primary factor limiting grizzly bear populations. Research indicates that 77 to 85 per cent of radio-collared grizzlies die at the hands of humans
[pdf], and between 17 and 54 per cent of human-caused mortalities go unreported.
Sustainable levels of human-caused mortality range from 2.8 per cent to 4.9 per cent. This means grizzly bear populations in productive habitat and/or with high reproductive rates can withstand 4.9 per cent annual human-caused mortality. Populations in moderate habitat and/or with low reproductive rates, however, can only withstand human-caused mortality rates of 2.8 per cent or less. Mortality rates of females, the reproductive engines of any population, should not account for more than 30 per cent of all mortalities.
Fortunately, populations plagued by human-caused mortality can rebound. For instance, populations have increased substantially in the Yellowstone and Northern Continental Divide recovery areas of the U.S. thanks to policies that reduced motorized access to grizzly habitat.
The loss and fragmentation of habitat is a primary cause of species decline worldwide. Habitat fragmentation occurs when parts of a landscape are transformed or destroyed. This can lead to smaller and more isolated populations that become more vulnerable to local extinction due to extreme events such as fire, disease, and human-induced mortality, and to the negative effects of inbreeding depression. The more fragmented the habitat, the more likely species will be negatively impacted.
(Photo Credit: Nathan DeBruyn)
Habitat alteration and fragmentation result primarily from human activities, including resource extraction, agriculture, energy generation and transmission, recreational activities, and settlement. Even inside national and provincial parks, undisturbed habitat is shrinking and grizzly bears are displaced by interactions with humans and development.
Roads and trails can reduce the movement of bears to the point that it influences the genetic composition within and among grizzly bear populations. Grizzly bears, especially adult females, are reluctant to cross highways, which can reduce gene flow and immigration and result in population isolation and decline.
In the short term, habitat loss and fragmentation can lead to poorer nutrition, lower reproductive rates, and higher levels of human-bear conflict and human-caused mortalities. In the long term, habitat loss and fragmentation lead to decreased population health, population decline and, eventually, extinction.
On top of fragmenting habitat, roads and trails in grizzly territory can result in bear deaths caused by poaching, self-defence, and wildlife-vehicle collisions. Increased access can also displace grizzly bears from high-quality habitat, decreasing their ability to find adequate food.
A study in the Alberta portion of the Central Rockies Ecosystem
found that 89 per cent of human-caused grizzly mortalities occurred within 500 metres of a road on provincial lands, and 100 per cent of human-caused mortalities occurred within 200 metres of a trail in national parks. On Alberta’s northern East Slopes, grizzly survival rates decreased as the density of roads increased. Because female grizzly bears spend more time close to roads than males, they are in greater danger of getting killed.
Even within protected areas such as national or provincial parks, roads and trails displace grizzly bears from their preferred habitats and increase grizzly bear habituation. This in turn increases in human-bear conflicts, which eventually end in bear deaths.
A simple way to decrease the numbers of human-caused bear deaths is to limit the number of roads and trails in grizzly habitat.
Habitat security (i.e. maintaining adequate levels of protected habitat) is key for grizzly conservation. It reduces the number of human-bear encounters and, in turn, human-caused bear mortalities.
Secure habitat must be located more than 500 metres from a well-used road or trail (though it can contain roads and trails no longer in use). It must also be at least 10 square kilometres in size
Grizzly bear populations must be large and well-distributed enough to withstand chance events, such as accelerated climate change, large-scale habitat changes like fires and floods, and disease. The greater the number of bears and the greater the extent of their geographic range, the lower the risk of decline and extirpation.
History has shown that grizzly bear populations of less than 250 individuals are prone to decline; a population of 40 – 125 individuals is critically low and vulnerable to extinction. Isolated populations of 50-90 bears have little chance for survival without dramatic intervention.
Some research suggests that grizzly bear population units should be at least 500-700 individuals to outlast the vagaries of catastrophic natural events, food availability and human behaviour and survive for hundreds of years. An “evolutionary robust population” (i.e. one that can maintain genetic diversity and population persistence over thousands of years) must be greater than 2,000 individuals.
The International Union for the Conservation of Nature (IUCN) guidelines recommends that, in general, wildlife populations maintain more than 1000 mature breeding adults to prevent unacceptable risk of decline (breeding adults make up only approximately 50 percent of any given grizzly bear population). The IUCN states that populations smaller than this 1000 should be listed and managed as “vulnerable” (“threatened” in B.C.), while populations with less than 250 mature breeding adults should be listed and managed as endangered.
Just over half of Canada’s grizzly bears live in B.C. (approximately 15,000) and Alberta (750). The rest (approximately 10,000) are found in the Yukon, Northwest Territories and Nunavut (although a few have wandered into northern Saskatchewan and Manitoba for the first time in over a century). Only about 11,500 of Canada’s grizzly bears are mature (i.e. breeding) individuals.
Estimates of grizzly bear population size and trends are uncertain in Canada, though. Although Alberta has undertaken DNA-based population research
[pdf], most of B.C.’s estimates are based on expert opinion or extrapolations from small study areas.
What we do know is that the healthiest subpopulations of bears in western Canada are found largely in northern B.C., where productive grizzly habitat is still relatively remote and inaccessible. In southern B.C., subpopulations have been isolated by urbanization, oil and gas development, mining, highways, and a vast network of backcountry roads. A similar situation exists in southern Alberta.
More than a decade ago, the BC government identified nine “threatened” Grizzly Bear Population Units (GBPUs, i.e. subpopulations) in southern B.C. These GBPUs are small, isolated and/or increasingly threatened by unsustainable levels of human activity. All but one are estimated to be well below 100 individuals, and four are smaller than 30 bears.
One GBPU was thought to have disappeared altogether, but one grizzly was recently spotted. The North Cascades GBPU is estimated to contain six grizzlies, though a verified sighting hasn’t occurred in many years. Even if there are a few individuals in these two subpopulations, they already are functionally extinct, and will disappear forever without intensive intervention.
Despite this, these threatened GBPUs are not listed as such under the BC Wildlife Act
. So while they cannot be hunted, they aren’t protected in any other ways.
(Photo Credit: Nathan DeBruyn)
Unlike their cousins in B.C., grizzly bears in Alberta are listed as a threatened species under Alberta’s Wildlife Act
. Like the grizzly bear population in BC, Alberta’s population has been fragmented into seven population units. Six are estimated to be smaller than 100 individuals, and four are highly threatened with decline and extirpation.
Several megaprojects threaten grizzly bear populations. These include:
- The proposed Site C Clean Energy Project is a massive hydroelectric generating station on the Peace River in northeast B.C. It will flood more than 100 kilometres of the Peace River Valley. This valley is a major corridor for grizzly bears, as well as migrating birds, caribou and other ungulates. In the Peace River Valley, there are resident grizzlies, which live there year-round, and transient grizzlies, which use the area as a corridor.
- The $1 billion Jumbo Glacier Alpine Resort, which was approved in early 2012, will be the country’s first year-round, glacier-based ski resort. Located near Invermere, B.C., it will encroach upon grizzly bear territory, specifically the Central Purcell Grizzly Bear population, which has only 176 surviving individuals. The development will put these last remaining bears at greater risk of mortality from poachers, hunters and vehicle accidents due to road construction that will carve up their territory and cut across corridors.
- Parks Canada last year approved the large-scale summer use of Banff’s Mt. Norquay ski area, key habitat for grizzly bears and other wildlife.
- The Northern Gateway Pipeline, proposed by Edmonton-based Enbridge Inc. to carry crude oil from the Alberta tar sands to the port of Kitimat, B.C., for loading onto supertankers, threatens grizzly bears and their habitat. The pipeline will traverse the Great Bear Rainforest, a sanctuary for B.C.’s grizzlies among many other kinds of wildlife. Experts consider a pipeline spill in this pristine wilderness to be inevitable, given Enbridge’s woeful record of pipeline maintenance.