It's the only place in the continental U.S. where mountain lions, gray wolves and grizzly bears share habitat - along with black bears, coyotes, lynx, wolverines, whitetail and mule deer, elk, moose, a smattering of cattle and a growing population of humans.
"No other ecologic complex exists like it," says Maurice Hornocker, director of Hornocker Wildlife Research Institute at Moscow, Idaho.
Glacier Park and its wide-open habitat occupy the east bank of the North Fork. Only about 3 percent of the land along the river is privately owned. No amenities and a rough road buffer the region from the developmental Sturm und Drang roiling the nearby Flathead Valley.
But that remote character is changing. Extensive logging has bared vast expanses where wildlife once could travel covertly. The hillsides are scarred by new roads.
"Big trees are hard to find," says John Frederick, owner of a hostel in the area and head of the North Fork Preservation Association. A sweeping 1988 forest fire wiped out many trees, he says, and "logging didn't help any."
Estimates show only some 200 to 250 people inhabit the North Fork, most of them summer or weekend visitors, but new vacation homes go up each year. They dot landscapes grizzlies historically used to travel from Glacier Park to the Whitefish Range and back again.
How much development can the area's grizzlies take? That's what a U.S. Fish and Wildlife study is trying to determine.
"It doesn't take a rocket scientist to say development affects bears," says Chris Servheen, leader of the study. "What we want to understand is how bears respond and how their mortality is affected - and what to do about it."
Servheen and his research team are tracking the movements of 15 grizzlies, both inside and outside Glacier Park. The scientists hope to chart the areas in the valley bottom grizzlies prefer for travel between mountain ranges. The scientists then will plot maps to show precisely what areas grizzlies are frequenting - the "linkage zones' - and which they are avoiding.
Ultimately, Servheen will work with private landowners, the U.S. Forest Service and Park Service, and the state Department of Fish, Wildlife and Parks to write a management plan for the North Fork with grizzlies in mind.
Meanwhile, wolves and mountain lions are making a difference for the North Fork's bears. Wolves have ganged up on grizzlies at least once. On an Oct. 25, 1993, radio-tracking helicopter flight, U.S. Fish and Wildlife Service researcher Nancy Kehoe got what she called a "special wildlife observation." She saw a pack of 17 to 18 wolves attacking a grizzly sow and her young cub.
The pack separated mother and cub, alternating its pursuit from one to the other. Kehoe and her pilot watched the attack for about five minutes, until the bears apparently scrambled up trees and out of harm's way. Later the researchers looked for signs that the grizzlies had been killed, but found none, Kehoe says.
More often, grizzlies benefit from sharing the land with wolves, as well as with lions. Bears sometimes snatch kills from lions, says Hornocker, and they feed off carcasses left by both lions and wolves. At least one North Fork grizzly didn't hibernate in 1992-93, preferring to spend his days reaping the rewards of his competitors' winter kills.
During a two-month study last year, wolves stole 18 fresh carcasses from 10 lions - more than one-quarter of the felines' 65 kills.
How all this competition for food affects prey is the question doctoral candidate Kyran Kunkel is asking. Working from a private cabin about 10 miles from Canada, Kunkel is the latest in a string of University of Montana biologists studying wolves since the first pack, known as the "Magic Pack," migrated south across the border some dozen years ago.
Kunkel is in the second year of a three-year look at the effects of gray wolves on ungulates - the deer, elk and moose they feed upon. He tracks several wolves from each of four study packs north and south of the U.S.-Canada border.
Along the North Fork, whitetail deer appear to be hardest hit. Wolves, lions, bears and humans are killing more deer than the herd can sustain, Kunkel says.
Elk numbers are declining or stabilizing in the North Fork Valley, although mountain lions may be more to blame than wolves, Kunkel thinks.
Meanwhile, wolf populations appear to be reaching a balance. Two packs totaling 32 wolves now live along the North Fork. Kunkel also monitors two packs north of the U.S.-Canada border, numbering 10 and five wolves. Five pups have been discovered in one Canadian pack.
When his work is finished, Kunkel hopes to have some solid information on how wolves affect deer, moose and elk populations, so public agencies can better decide management actions. The idea, he says, is to maintain healthy populations of both predators and prey.
While wolves compete with lions for prey, lions may actually be food for the wolves, says Hornocker.
Since 1992, Hornocker's teams have used dogs to track, tree and collar lions both outside and inside Glacier National Park - the first time the park allowed dogs inside its borders.
Wolves followed lion tracks at least six times last year, Hornocker says, and treed lions as many times.
Hornocker hopes to spend at least three more years in the area studying lion-wolf dynamics. Although public agencies have turned down his requests for funding, Hornocker says he'll make his results available to anyone. That includes wolf recovery experts at Yellowstone National Park.
* Sherry Jones
Sherry Jones writes in Kalispell, Montana.