A Canadian Park Grizzly Study Underscores the Need to Minimize Human-Caused Mortality in Highway-Served Peripheral Areas

Grizzly sow and cubs in Yellowstone National Park. Minimizing human-caused mortality of reproductive age females is an especially important goal. NPS photo.

Grizzly bears inhabiting national parks commonly wander outside the parks into human-modified peripheral areas, run afoul of various lethal hazards, and end up dead. A recently-published study of grizzlies in a Canadian park shows that empirical habitat modeling can be a highly useful tool for bear management and provides additional support for the argument that minimizing the direct mortality loss of out-of-park bears is vital to the long-term success of bear management programs.

Grizzlies are very sensitive to the impacts of human activities, especially human-caused mortality, because they are large predators that range over large areas, occur at low population densities, reach breeding age slowly, and produce small numbers of young that require lengthy maternal care. No national park with resident grizzlies is sufficiently large to keep all of the bears inside the park boundaries all of the time. Dispersers -- commonly two-year olds driven away by their mothers -- and mature bears seeking food, mates, and other needs may roam and forage in peripheral areas for days, weeks, or longer before returning to the park or moving into other protected areas.

Many grizzlies do not return at all, but instead fall victim to the perils awaiting them on their out-of-park treks. Some die in bear-vehicle collisions on the highway. Others are shot by hunters or poachers, killed for livestock predation, or dispatched for threatening (or appearing to threaten) livestock, pets, or people. For these and related reasons, out-of-park bears are at serious risk of what wildlife biologists refer to as human-caused direct mortality.

Wildlife biologists know that you can't have effective bear conservation without understanding the dynamics of bear mortality. That's a job for researchers. If you are rooting for the grizzlies in America's national parks, you should be grateful that there are scientists in the U.S. and Canada working very hard to monitor grizzly populations, understand their habitat needs, and learn just how much grizzly mortality occurs where, when, why, and with what consequences. They are accumulating invaluable knowledge that bear managers can put into practice.

Field studies employing scientifically rigorous methods are of vital importance because they help to unlock the remaining mysteries and provide empirical evidence needed to put bear management on a scientific footing. Without this empirical evidence you just have varying degrees of guesswork.

Against this background, a Canadian study merits attention. An article entitled Bears and Humans: How Canadian Park Managers Are Dealing with Grizzly Bear Populations in a Northern Landscape recently published in ParkScience (Vol. 27[2], Fall 2010) reported the salient results of a years-long research project by bear biologist Ramona Maraj that was centered on grizzlies inhabiting Canada's Kluane National Park and Reserve (Kluane).

Kluane is a huge park (8,500 square miles) situated in southwestern Yukon Territory where it adjoins another Canadian park (British Columbia's Tatshenshini-Alsek Park) and two American national parks (Alaska's Glacier Bay National Park & Preserve and Wrangell–St. Elias National Park & Preserve) to form the world's largest international protected area. This protected area is renowned as one of North America's last remaining strongholds for grizzly bear populations. Kluane is known to function as an important "source population" for surrounding areas.

In the precisely stilted language of scientific discourse that ParkScience uses, Maraj's research:

examined the efficacy of ecological models designed to identify potential conflicts among people and grizzly bears with the goal of enhancing management and survival of this apex predator in and around Kluana National Park and Reserve, Canada.

In other words, Maraj investigated the role of habitat alteration and related activities in grizzly-human conflicts, hoping that the knowledge gained could be used to help Kluane's grizzlies survive. The study employed, among other data, nearly 4,000 aerial VHF telemetry relocations for 69 bears collared during 1989 to 2004.

If you want to read the entire report, you'll find it at this site..

The gist of it is this:

• To manage Kluane's grizzlies effectively, you must know which landscape features are inherently attractive to the bears and how that attraction is modified by human land-use and presence. Some biologists have argued that empirical habitat models can do a better job of explaining these crucial factors than expert-opinion models currently in use, but solid proof has been lacking. This study shows that, at least in the case of the Kluane bears, empirical habitat modeling using collared-bear telemetry relocation data and foraging information yields better results than expert-opinion modeling.

• Peripheral locations adjacent to highways are attractive to Kluane bears, but inflict such high rates of human-caused mortality (around half of it due to management kills of nuisance bears) that they function as "attractive sinks." Left unchecked, the losses occurring in these hazard-laden peripheral areas -- especially the loss of reproductive-age females -- can seriously undermine other managerial efforts to sustain the Kluane grizzly bear population.

• To conserve grizzly bears in Kluane, it will be necessary to reduce human-caused mortality on the park periphery and develop a transboundary management strategy.

• In the final analysis, it is people management, not bear management, that matters most. "The difficulty of coexisting with grizzlies and other large carnivores is less about the carnivores than about societal values and perceptions." Thus, insuring the grizzly's future requires convincing people that they should cooperate in ways that reduce the human-caused death of bears.

These are certainly not startling revelations. Nevertheless, the conclusions of this study are noteworthy for the great care that was taken in acquiring and analyzing the information on which they are based. That's the way science works. You don't just say that something is obviously true and leave it at that. You prove it's true, develop a nuanced understanding of it, and try to put the knowledge to work in ways that matter. The results of this particular study should have implications for the management of grizzlies in Yellowstone National Park, Glacier National Park, and the many Alaskan NPS units with grizzlies (including, of course, Kluane neighbors Wrangell-St. Elias and Glacier Bay).

Postscript: In the Acknowledgements section at the end of the article, Maraj thanks the numerous agencies and organizations that provided funding and other support for her dissertation research. The final sentence is one that you just have to love: " I am especially grateful," she says, "to the many bears that wore collars during this study."