Grizzlies and Environmental Health: A Keystone Species Helps Assure Biodiversity

June, 20 2016  |  by kevin Back »

Where a Grizzly Can Walk, the Earth is Healthy and Whole


By Lisa Densmore Ballard

Within the alpine and subalpine woodlands of the northern Rocky Mountains and the great coastal forests of the Pacific Northwest, grizzly bears are opportunistic feeders. They eat what’s available depending on the season. In the early spring after hibernation, they graze on newly emerging grasses and scavenge winter-kill carcasses. In late spring, they mostly eat sprouting grasses and sedges, flowering glacier lilies and spring beauties, while a few learn to prey on newborn elk, moose and other immature ungulates. In summer, they dine on a variety of plants, roots, insects and rodents. Some learn to feast on spawning trout and salmon from streams, and on berries and white bark pine nuts. In the fall, in preparation for hibernation, they gorge on as much high-calorie food as they can find, gaining three to six pounds per day! These large omnivores certainly have a presence in their wild neighborhoods. As a result, they are often called a “keystone species.”

A Keystone Species

Grizzly bears are often viewed as a barometer of an ecosystem’s health. Photo by Lisa Densmore Ballard.

Grizzly bears are often viewed as a barometer of an ecosystem’s health. Photo by Lisa Densmore Ballard.

The term “keystone species” is named for the keystone at the top of an arch. If you remove that stone, the arch collapses. A keystone species plays the same role in an ecosystem. Extirpate the animal, and the ecosystem changes dramatically. The phrase was coined in 1966 by Robert Paine, a biologist studying intertidal zones in the Pacific Northwest, to describe the Pisaster starfish, an aggressive hunter that eats barnacles, freeing up critical space on rocks. Paine found when the starfish were present and active, there was a wider array of sea life present.

Grizzly bears might or might not be considered a keystone species depending on whether you take an ecological or a conservation point of view.

“The term keystone species is thrown around a lot,” says Chris Servheen, Adjunct Research Associate Professor of Wildlife Conservation at the University of Montana’s College of Forestry and Conservation, “It applies to grizzly bears in a conservation context because, if you manage for this species, it carries others with it. If you protect grizzlies, you protect other animals. However, if you mean fundamental to an ecosystem, it doesn’t exactly apply. If you remove grizzly bears, there won’t be massive change, like removing zooplankton from the ocean.”

An Umbrella Species

Perhaps “umbrella species” is a more accurate term. According to Servheen, if grizzly bears have an adequately large home range which is safely connected to other large tracts of wild land, other species flourish along with the bears.

Doug Chadwick, a wildlife biologist and one of Vital Ground’s founding board members agrees. “A grizzly bear doesn’t have a specific role as, say, wolves in Yellowstone, the dominant carnivore there, because bears are generalist omnivores.” Chadwick likens bears to heavy-weight gardeners.

“A grizzly bear is the primary earth mover in the high country,” he says, “It digs for bulbs, ground squirrels, voles and marmots. Its long claws rake and turn over huge areas. Over the years, large areas are furrowed, pitted and worked by bears which brings up nutrients from lower levels of soil and creates more diverse, more productive wildflowers.”

Alpine Bluebell by Lisa Densmore Ballard.

Alpine Bluebell by Lisa Densmore Ballard.

Through their feces, bears also distribute tens of thousands of seeds from huckleberries, chokecherries, currants, mountain ash and pine nuts. And grizzlies that scavenge carcasses and those that learn to fish for trout or salmon spread around natural fertilizers.

“Bears enrich and increase the variety of the ecosystem,” Chadwick says. “Remove them and everything else becomes less vital.”

Like Servheen, Chadwick also uses the term “umbrella species” to describe the role of a grizzly bear in the area where it lives. “It’s a charismatic animal, like Orcas in the ocean, that draws attention to its environment,” he says, “A bear’s range is big, and it uses every elevation from the valleys to the mountaintops. If you take care of grizzly bears, you protect the swans and glacier lilies, too.”

Grizzly Bears Need Secure, Secluded Space

However, the size of a grizzly’s range also a major challenge in conserving it. To thrive, bears need space away from humans, yet both bear and human populations are growing in bear country, sometimes encroaching on each other.

“Habitat security is mainly affected by motorized routes,” says Servheen, “Bears avoid motor vehicles which eliminates habitat. Vehicular routes also increase mortality risk because they increase poaching and hunting. If you lower motorized access to land, there’s better bull-cow ratios among elk because you’re not selecting out the biggest, strongest bulls. Grizzly bears have a direct conservation umbrella effect on elk. It applies to moose and deer, too.”

Servheen also emphasizes the importance of keeping bears out of the front country at campgrounds and around livestock, and in the backcountry at tent sites. “When you electrify a chicken coop or hang your food while camping, you do it for the grizzlies, but it carries over to coyotes, black bears and raccoons,” he says, “The key to success is letting people know how to live with bears through education and outreach rather than dealing with the situation after a bear gets into trouble. Once a bear gets conditioned to humans, you can’t remove it far enough.”

Trumpeter swans by by Lisa Densmore Ballard.

Trumpeter Swans by Lisa Densmore Ballard.

Servheen also points to improving connectivity between tracts of bear-friendly habitat with crossing structures along highways and through private easements and land acquisitions, a key part of Vital Ground’s mission.

“It’s not about whether you like grizzly bears or not,” says Chadwick, “If a place is big enough and wild enough for grizzlies, the water is clean. You can camp without thousands of people around. You can see wildflowers, bird watch, hunt elk, fish…These are values we hold dear when we are in wild places.”

An award-winning professional photographer and writer based in Red Lodge, Montana, Lisa Densmore Ballard contributes regularly to over 30 regional and national magazines. To learn more about Lisa, go to

Where the Grizzly Can Walk, the Earth is Healthy and Whole

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