On July 14, 1993, a U.S. Fish and Wildlife Service crew trapped a 2-year-old female grizzly bear in British Columbia's Flathead Valley, a wild river-carved lowland just northwest of Glacier National Park. Officially, the 80-pound grizzly was designated Bear 286. Unofficially, the crew named her Irene.

The team fitted Irene with a radio-collar, packed her onto a truck and drove 150 miles through the night to the Cabinet Mountains, a rugged swath of snow-covered peaks and conifer forests tucked in Montana's northwest corner. The next morning, biologist Wayne Kasworm turned Irene loose near Lost Girl Creek.

Rarely had such great expectations been pinned on a single animal. Irene had been designated one of the involuntary saviors of the Cabinet-Yaak Ecosystem, a 2,600-square-mile region on the Montana-Idaho border abutting Canada. It's one of six designated recovery zones in the Lower 48 where the federal government aims to protect or boost threatened grizzlies. While some recovery zones, like the lands around Glacier and Yellowstone national parks, supported growing populations, bears in the Cabinet-Yaak were spiraling toward extinction. Kasworm estimated that only 15 bears roamed the Cabinets.

Kasworm believed the only way to save the population was to supplement it with more grizzlies. The strategy, called augmentation, made biological sense, but it was politically contentious. The same year Irene moved to the Cabinet Mountains, a biologist who hoped to transplant bears to Washington's North Cascades was spat on at a public meeting. "Nobody had ever moved bears to bolster a population before the Cabinet-Yaak program," Kasworm recalls. "Obviously, it was a controversial idea."

Today, though, the strategy appears to have paid off: According to a recent DNA study, around 45 grizzlies now reside in the Cabinet-Yaak. Once on the verge of vanishing, the population is nearly halfway to 100 – the threshold at which it would be deemed no longer at risk.

The bears' persistence gives scientists hope that the Cabinet-Yaak could someday serve as a node of connection for isolated pockets of grizzlies throughout the Rockies. Yet that optimism is tempered by serious challenges, none greater than keeping bears alive in a landscape shared with humans.

In 1987, when Kasworm first floated the idea of transplanting bears to the Cabinet Mountains, locals responded with suspicion. Previous recovery efforts had been blamed for the region's floundering timber economy and the closure of backcountry roads. "When I was a kid, people would drive up to our house excited because they'd seen a bear," says Bruce Vincent, a logger whose family has lived around Libby, a town of 2,700 that's the Cabinet-Yaak's largest population center, since 1904. "But attitudes changed. The bears became 'goddamned grizzly bears.' "

Vincent wasn't opposed to augmentation, but he and the USFWS agreed that locals deserved a voice in how it was implemented. He and other community leaders, including elected officials and timber and mining industry representatives, created a committee to guide the plan. Kasworm agreed to delay relocation to hold meetings and modify the program.

Finally, the committee consented to a conservative experiment: Starting in 1990, Fish and Wildlife would relocate four young females over a five-year period. If the bears stuck around and reproduced, the augmentation would proceed. If not, it would be years before the scientists got another shot. "That citizens committee was how we were able to pull this off," Kasworm says.

Initially, though, the bears didn't cooperate: The first shed her radio-collar and disappeared, and the second was found dead just a year after being released. Irene, however, survived and stayed out of trouble. Kasworm gave biweekly updates on her whereabouts on a local radio show.