Dangerous yet delicate: Grizzly bears are a key indicator of BC's ecological health

January 10, 2014 - Kim Westad

Though polar bears have become symbolic as a species put at risk by climate change, UVic research shows why the grizzly bear may be a better indicator of BC’s ecological health.

They inspire awe, fear, and are viewed as an international symbol of the Canadian wilderness. But who’d have thought that grizzly bears, those great lumbering creatures with the teddy bear faces and claws as long as human fingers, might also be the modern day version of the canary in the coalmine?

For all their size—it’s not unusual for a male grizzly to weigh 800 pounds or rise to eight feet when standing on its hind legs —grizzlies are among the most sensitive animals in the world. They are more sensitive to changes in their environment, such as food, development or human encroachment, than many other much smaller species.

Their numbers have been decimated over the last century. At one time, you could have walked grizzly bear trails from coastal Alaska down to northern Mexico, stopping at hundreds of salmon streams along the way. These days, explains UVic researcher and geography professor Chris Darimont, the bear trails stop in Howe sound, north of Vancouver, and the salmon runs have become mere ghosts of their former selves in Oregon and California.

A species at risk

More than half of Canada’s grizzly bears live in BC—about 15,000. Alberta has an estimated 750. The rest—about 10,000—are in the Yukon, Northwest Territories and Nunavut. Grizzlies are listed by both the provincial and federal governments as being of special concern.

Their numbers are threatened by a variety of factors, most caused by humans, say researchers. Unsustainable hunting, poaching, recreational and industrial development, fisheries management policies that reduce the number of salmon available for grizzlies as a food source—all affect grizzly bear populations.

Reducing impacts requires a change in priorities in environmental management, says Darimont, and a shift away from viewing grizzlies as big game trophies to seeing them as an essential part of the environmental landscape. If grizzlies are healthy, the environment is healthy, researchers say.

The reverse, unfortunately, is also true.

A trophy species, but for whom?

Minnesota Wild player Clayton Stoner ended up with more publicity for his grizzly bear hunting than his hockey playing this fall.

A photo of the NHL defenceman holding a severed grizzly head went viral, focusing public attention on the contentious issue of trophy hunting. The grizzly, known to locals as Cheeky, was shot in the Great Bear Rainforest, on BC’s north central coast. Stoner had one of the limited-entry licenses given out by the province each year to hunters who can then kill bears in designated areas. Hunters can use high-powered rifles equipped with powerful scopes. They usually want the heads, coat and paws of the animal, and leave the meat and carcasses behind.

Province-wide, tourism revenues from the hunting, guiding and charter aircraft involved are estimated at $300-million a year. The province says that the number of hunts allowed is based on sustainable limits, as determined by an independent panel of grizzly bear scientists. Harvest levels vary throughout the province, depending on the number of bears in each area, the estimated productivity of the bears and the known number of mortalities.

But joint research from UVic, Simon Fraser University and the University of British Columbia published this fall in the scientific journal PLoS ONE found that grizzlies were over-hunted in half the areas where the province permitted hunting, with large discrepancies between the upper limit to kills set by the provincial government and the number of bears actually killed. Almost all were associated with trophy hunting, says Darimont, the study’s co-author and the Raincoast Conservation Foundation science director. The study was based on a 10-year audit of the province’s own numbers.

Of particular concern was the finding that of the 3,500 grizzlies killed during the study period, more than 1,200 were females—the “reproductive powerhouses of populations,” says Darimont.

A delicate reproductive cycle

Hunters are not required to target males, but are encouraged to because of the challenges in grizzly reproduction.

Female grizzly bears don’t produce their first litter until they are about five or six years old. Delayed sexual maturity, together with a three-or-more-year interval between litters, results in a low reproductive rate. Bears usually live between 25 to 30 years.

Research has also found that adequate food sources for grizzlies play a large role in reproduction.

When a female grizzly becomes pregnant, the development of the embryo temporarily stops for several months, a process called “delayed implantation.”

If a female bear is unable to gain enough weight during the summer and fall before hibernation, she miscarries because of the lack of nutrients and caloric intake.

If the female finds enough food and is healthy enough to hibernate—grizzlies can gain two pounds a day and sometimes eat 90 pounds of food a day during the warmer months—she will give birth in the den in January or February to one to four cubs, usually two. These hairless, blind and toothless cubs weigh about one pound. The mother nurses her cubs in the den until they all come out in late April or May.

Food supply, particularly salmon, is therefore crucial for grizzly bear reproduction, one of the findings of another study published this fall in PLoS ONE, co-authored by UVic researchers, including Darimont.

Salmon: the centre of the food web

The fall salmon season provides the nutrient-rich food the bears need before hibernation. Grizzly bears with access to salmon have higher population density, body size and litter size, says the study.

The researchers from UVic, the University of Calgary and the Raincoast Conservation Foundation also found that grizzlies with reduced access to salmon were more stressed, which could have other negative long-term health effects. The findings came after examining stress hormones in hair samples of grizzlies from the 30,000-km2 Heiltsuk Territory on BC’s central coast. Researchers used hair strands from the huge animals to measure their cortisol, a stress hormone. Using molecular markers, they could also tell how rich in salmon a bear’s diet was and to which individual bear the hair belonged. The researchers tempted grizzlies to barbed-wire hair snags by dousing fermented fish oil in a pile surrounded by barbed wire. The bears stay only for a smell and are off, leaving a few tufts of hair behind.

The study shows the importance of resource management that keeps all users in the equation. The odds are stacked against grizzlies, says a growing body of work. Fisheries, primarily the commercial sector that target the salmon species favoured by bears, capture salmon en route to spawning grounds before they even become available to grizzlies.

Darimont’s previous work, published in PLoS Biology, showed how such intense competition by fisheries can suppress bear densities. The new hormone research reveals the probable mechanism: birth rates and litter sizes are likely reduced by the stress response from low salmon.

When salmon are plentiful, however, it’s more than the bears that benefit. UVic’s Tom Reimchen (Biology) first discovered how bears eat the nutrient-rich brains and eggs, casting aside the remainder of the fish to feed other animals and fertilize the forest.

Mapping the contact zone

Examining ways that grizzlies and human activities can co-exist is a big part of Trisalyn Nelson’s work. The UVic geography professor and her students recently worked with the Foothills Research Institute, publishing research in PLoS ONE about the impacts of habitat conditions and human disturbance on the long-term stress and health of grizzly bears in northern Alberta.

Researchers can’t ask a grizzly why it prefers one patch of berries over another, or how a bear adapts in former wilderness areas that are logged, mined or used for recreation.

But the animal’s travel patterns—collected via satellite collars—speak for them. For example, mapping found that female grizzlies spend more time than male bears near roads. That puts them at a higher risk of human-caused mortality, either from poaching or being struck by vehicles. And losing more females from the grizzly population is a serious conservation concern.

Another model: coexistence in nature

Where do researchers and society move from here? Darimont and others are strong advocates of changing how society views grizzlies. Rather than trophies for a few, they could provide education and a conservation economy for many. Among several First Nations partners, he works with the Kitasoo/Xai’xais Nation on BC’s central coast and their Spirit Bear Lodge and Spirit Bear Research Foundation to monitor the grizzly and white bears. Other partners include the Hakai Beach Institute, funded by the Tula Foundation, who support research programs that address the complex nature of conserving, managing and restoring the central coasts unique marine and terrestrial ecosystems.

“Collectively, we envision a near future in which the extractive industries that threaten bears in their territory—forestry, over-fishing, trophy hunting—are increasingly substituted with bear eco-tourism,” says Darimont.

Imagine, say researchers, a time when Cheeky, the five-year-old bear shot last year, would still be alive, providing education and benefit to the world for another 20 years.

“What we are doing to bears we are ultimately doing to ourselves,” Darimont says. “To think that humans will somehow evade the effects of ecological damage we bring to the world is to ignore reality.”