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Bear biologist sees human management as major challenge
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Bear biologist sees human management as major challenge

From the Grizzlies and Us: Explore the uneasy coexistence of bears and humans series
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When Kerry Gunther goes backpacking, he likes to visit the desert Southwest.

There’s two reasons the lead bear biologist in Yellowstone National Park cites for his penchant to travel south. One is that he has more time off in the winter, when bears are hibernating, and the weather in the Southwest in winter is fairly mild and free of tourists. The other reason is that he doesn’t have to worry about grizzly bears when he pitches his tent.

“You don’t have to have that in the back of your mind,” he said.

The rest of the year, when bears are roaming the landscape, black bears and grizzlies are always top of mind for Gunther, who has spent 39 of his 62 years working with bruins in the nation’s first national park.

“There are so many ways they can come into conflict with people, usually at the fault of people, and we get called to deal with them,” Gunther said.

Bear Highway.jpg

A grizzly bear cruises down a road in Yellowstone National Park in 2015 along Swan Lake Flat. For the most part, grizzlies tend to avoid developed areas in the park.

Bear abode

Thanks to the protection provided by the creation of Yellowstone National Park, Gunther works in one of the few places grizzly bears have survived the onslaught of Euro-American settlement of the lower 48 states. While the big bruins were hunted and trapped to extinction elsewhere, grizzlies were able to hide out in the more than 28,000 square miles of the Greater Yellowstone Ecosystem.

Even with that protection, however, grizzly numbers in the GYE dropped to an estimated low of only 136 animals in the mid-1970s, although verifying that figure for a species that occupies remote terrain is difficult. Due to the low bear populations, in 1975 the species was protected by the U.S. Fish and Wildlife Service under the Endangered Species Act.

Dan Wenk noted in the book “Yellowstone Grizzly Bears: Ecology and Conservation of an Icon of Wildness” that grizzlies were scarce when he first worked in the park from 1979 to 1984. He saw only five in that entire period. When Wenk returned to Yellowstone in 2011 as superintendent, he noticed a distinct shift. In one day on a drive through the park he counted 10 grizzlies.

Kerry Gunther.jpg

Yellowstone National Park bear biologist Kerry Gunther has seen a lot of changes in 39 years, including a rebound in grizzly bears and the continuing growth of tourism.

“It was abundantly clear that this was a different park than the one I left more than 25 years earlier,” he wrote.

Thanks to recovery efforts, the GYE’s grizzly population is now estimated by wildlife officials at 690 bears with an asterisk. Bear populations could be underestimated by 40% to 50% agency scientists claim.

“We probably reached ecological carrying capacity in the mid- to late-‘90s,” Gunther said. “The population is now pretty stable.”

Those figures have been challenged by grizzly advocates outside of federal and state agencies. Environmental groups have repeatedly and successfully fought to keep grizzlies on the endangered species list because of the many threats to traditional food sources. These include a 70% loss of whitebark pine trees, whose seeds are a high in protein, and dramatic declines in Yellowstone cutthroat trout and elk populations inside Yellowstone.

Bears have also weathered the 1988 fires in Yellowstone, which burned more than 800,000 acres, and the reintroduction of wolves which started in 1995.

Despite the loss of traditional foods, grizzly biologists note that Yellowstone’s bear population has grown due to the animal’s ability to adapt and its omnivorous nature. By collecting and analyzing scat, researchers identified more than 260 items on the grizzly bear’s menu, led by 20 to 30 most-consumed. What’s more, scientists noted through capture studies that, despite the decline in some food sources, grizzly bears have maintained healthy body condition.

“They can survive just about anything as long as we don’t kill them,” Gunther said.

However, loss of food sources can lead to bears seeking new home ranges outside of Yellowstone since competition for food can push less dominant bears out as males seek places to avoid confrontation, Gunther noted.

“They wander as far as they need to to eat,” he said.

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A grizzly bear crosses the road in Yellowstone National Park in 2014 near LeHardy Rapids. Populations of the big bruins seems to have peaked, with numbers estimated at more than 690 animals.


Wandering bears are the main reason for people management, Gunther noted. By bear-proofing dumpsters, homes and campsites, those bears don't receive food rewards that could make them associate humans with a meal.

“What’s fortunate for us is that almost all the (human) visitation occurs in developed areas,” Gunther said.

So the backcountry, where bears want to be, is mostly free of human encroachment. Visitor studies have shown the majority of the park’s 4 million annual visitors don’t get more than two to three miles away from boardwalks. Although there are 300 designated backcountry campsites, they are rarely filled every night.

“So bears still have millions of acres with little human use,” he said. “In the best habitat in the park, use can only get so high,” since backcountry use is controlled by a permit system.

Scientists continue to expand their knowledge of Yellowstone grizzlies, including a current study examining a decade of data from GPS-collared bears showing how they are utilizing the landscape in Bear Management Areas, which are temporarily closed or restricted to human access to avoid conflicts.

BMAs were created in 1983 to reduce bear-human encounters in designated areas, like around Old Faithful in the spring. Bears will seek out winterkill, often bison carcasses, to feed on after awakening from hibernation. The BMAs were created based on recommendations from park staff. The new study, expected to be completed by next spring, will pinpoint what habitat bears are using.

“Anything that restricts recreation use is controversial, so this will be helpful,” Gunther said.

At those backcountry campsites, the Park Service has made it easier for campers to safely store their food by installing metal “bear boxes” or poles to hang food out of a bear’s reach.

“If you make food storage easy and convenient, people will use it,” he said. “We’re trying to make it easier for people to do the right thing, which keeps bears out of trouble.”

The efforts have been largely successful, with few human-bear conflicts despite increasing visitation. Yellowstone visitors have a 1 in 63.4 million chance of suffering an injury by a grizzly bear, which drops to 1 in 1.7 million for those who camp inside the park.


In his tenure in Yellowstone, Gunther has seen visitation double from about 2 million people a year to 4 million.

“The ecosystem used to be very remote and rural, and now there are a lot of people living in the ecosystem,” he said. “So the human-bear interface is becoming more of a challenge.”

Some of those people are building homes in what is now referred to as the wildland urban interface, or WUI, next to national forests and trout streams seen as amenities that increase a property’s value. Such development means fewer places for wildlife to avoid contact with humans.

In the Greater Yellowstone Ecosystem, which extends outside the park, more people visiting to hunt and hike has also increased the number of human-bear encounters. The leading cause of grizzly mortalities in the GYE is from hunters shooting bears in the fall, when bruins are actively seeking food before hibernating. Some elk hunters joke that a rifle shot in the fall is like ringing a dinner bell for a grizzly.

“Currently, the highest proportion (30%) of all reported grizzly bear mortalities is associated with shootings by ungulate hunters (mostly self-defense kills), followed by conflicts with humans in developed areas (25%) and livestock depredations (19%),” according to the book “Yellowstone Grizzly Bears.”

Key to reducing these bear fatalities is greater education. Many hunters and hikers do not carry bear spray, a proven bear deterrent when successfully deployed. Even in Yellowstone, fewer than 30% of backcountry visitors carried bear spray, a park study found.

Finding a way to reduce bear-human conflicts will help build more social tolerance for the big animals on the landscape, Gunther said. The difficult part is that there are always some folks who are ignorant about how to recreate in grizzly bear country.

“They just don’t behave very well,” he said.

He cited three instances this summer when backcountry campers freaked out after seeing bears and abandoned all of their food and gear.

“That could have been bad for the bear and for the next people who camped there,” he said. “Just because you see a bear, it’s not going to kill you.”

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Yellowstone National Park's Albright Visitor Center gives tourists an introduction to wildlife in the park, including this grizzly bear display.


Gunther said Yellowstone probably reached its ecological carrying capacity for grizzly bears in the mid to late 1990s. Since 2001, scientists have recorded slow growth, partly due to lower cub and yearling survival – two ages that are difficult for scientists to monitor.

Despite a relatively small population when the animals were listed as threatened, studies have shown Yellowstone grizzlies have maintained genetic diversity. One of the goals of bear managers, however, is to increase the animals’ genetic diversity to help it withstand future challenges that climate change may pose. To do that without human intervention, grizzlies from the Northern Continental Divide Ecosystem need to migrate as far south as Yellowstone, or vice-versa. So far, that hasn’t happened, but Gunther remains optimistic that it could occur someday soon. If not, bear managers have the option to capture and release animals from each ecosystem to manually attempt to increase genetic flow.

One of the main complications is for a bear to successfully navigate the landscape between Glacier and Yellowstone national parks requires crossing highways, rivers and human development without running into conflict.

“Right now our genetic diversity is not at risk, but eventually if they don’t connect it could be,” Gunther said. “In the next decade or two, it could happen.”

Suggestions by park critics that bears are abandoning Yellowstone because of critical food shortages are unfounded, he said. Instead, the increasing bear population is what motivates some animals to leave the protection of Yellowstone.

“Our counts are pretty stable," Gunther said. "Collared bears haven’t moved.”

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Kerry Gunther said grizzly bears are an adaptable species, able to survive many challenges except human's killing them.



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