YELLOWSTONE PARK - The newly dug, foot-deep hole with vertical lines clawed into one side immediately catches Dave Mattson's eye.

He bends over to take a closer look and runs his fingers along the deep gouges. A wide smile breaks over his normally studious face as Mattson confirms his find - a snack hole for a grizzly bear.

The bear has been eating the dirt, probably to supply its body with phosphorous and sulfur, Mattson opines. He's quick to point out, however, that dirt is but a small part of the diet for Ursus horribilis. Meat, trout, pine cones and moths are what give the bruins their energy, and Mattson is worried that human interference is ruining those food sources.

Later, Mattson and other conservationists gather at a dude ranch tucked far up the Tom Miner Basin outside Yellowstone. They've been brought here by the National Resources Defense Council - a conservation group headquartered in New York City, with offices in Livingston, Washington, D.C., and California - to explain to a group of national and international journalists why, as one scientist put it, the grizzly bear as a species is not recovering and should not be taken off the federal list of endangered species.

The thrust of their discussion is focused on the grizzlies in what is known as the Greater Yellowstone Ecosystem, a mountainous range encompassing about 28,000 square miles in and around the national park in Wyoming, Montana and Idaho. The scientists and conservationists believe the four main energy food sources for the Yellowstone grizzlies are deteriorating, and that the bears need to be "connected" through "travel corridors" with small groups of other grizzlies in order for all not just to thrive, but even to survive.

"What it really comes down to is human activities and pathogens," Mattson says. "People can say bears will compensate by eating other foods, but the energy values of those other foods are a lot less. We almost certainly will see a decline of support from the ecosystem. So if we want the same number of bears, we have to spread them out over a much larger area.

"I think we will see the bear population declining by 5 percent per year … and it only takes 15 to 20 years to go from 600 to 200 bears. That's not a lot of time."

A few days later, from his office in Missoula, the man sometimes called the federal government's "grizzly bear czar" politely but firmly disputes the conservationists' belief that the grizzlies are not thriving.

"Anyone who lives in grizzly bear country knows that's not true," says Chris Servheen, a biologist with the U.S. Fish and Wildlife Service. "The fact is, the grizzly bear population is increasing 4 percent per year or more and has been for the past six years. To somehow say that would turn around, or they can predict that in the future, seems like somewhat of a stretch. If there were a decline, we would know that and could see it."

Servheen, a bear biologist with a Ph.D. from the University of Montana, counters that when he started monitoring grizzlies 23 years ago, only about 200 bears existed in the Yellowstone area. Now 500 to 600 grizzlies are spread out over 14,000 square miles, and they are expanding their range into places no one thought they could have. This year alone, researchers have already counted 100 cubs - and those are just the ones they saw.

"You would think that people would be celebrating this, that the population of the grizzly bear is robust and expanding. You would think this would be something people are happy about and proud of instead of providing forums where they say that all is lost," Servheen said. "I guess they can continue to try to engineer up a disaster - it just depends upon your level of imagination."

Corridors of life

Scientist Troy Merrill and others, including Servheen, believe an important part of a thriving grizzly population is a diverse genetic background. Servheen said Yellowstone bears have that; others aren't so sure.

But most scientists agree the best way to ensure a diverse gene pool is through "travel corridors" between the ecosystems where bears live.

Servheen's committee and numerous local and national environmental groups have been working with public and private landowners, as well as local governments, to try to keep and enhance what's left of viable travel corridors. They are trying to discourage subdivisions that break up open spaces. They are building a bridge for bears over I-90 near Bozeman Pass and working to prohibit logging or drilling on key state and federal properties.

They envision corridors west from Yellowstone to the Selway/Bitterroot region; from there north to the Cabinet/Yaak ecosystem, and possibly northwest to the Cascades. Another potential corridor runs north from Yellowstone to the Little Belts, Big Belts or Elkhorns, then on to the Rocky Mountain Front.

However, Servheen's group recently released a report stating that "the obstacles to achieving this connectivity are substantial."

These corridors not only have growing cities nearby, but people also are continuing to move into the mountains around Yellowstone, Missoula, Helena and Kalispell. Ski resort owners eye new, untracked terrain. And roads, for a wide range of reasons, crisscross the countryside, further disrupting grizzly corridors.

Then there's the fact that even if these corridors are in place, people can't make a bear migrate. If it does, there's no guarantee it will use these corridors that look so promising on maps. If it does use a corridor, there's no way to ensure it won't venture out into residential areas along the way.

"Bears don't stay on a trail from point A to point B," Servheen said.

To make the corridors work, bears would have to reside inside the migration routes, Servheen said. Establishing these populations outside of Yellowstone and existing wilderness or roadless areas presents a challenge, not only in getting bears there but in making people comfortable being in closer proximity to them.

At this point, more than half of the bears that die do so because of conflicts with people. Those conflicts usually develop on the periphery of the bears' existing habitat.

Servheen added that connecting Yellowstone to the other areas is most problematic because of all the development surrounding the park. However, he also believes bear recovery in Yellowstone isn't dependent upon linking them to other populations.

"Based on genetic sampling, we know it will be at least 30 to 40 years before they're genetically challenged there," Servheen said.

The new report by Servheen's group states that only two migrating bears per generation are needed to maintain the current level of genetic diversity. If the grizzlies don't migrate into other areas by themselves, it's possible to trap and move them.

The bears probably won't start to roam into these corridors until their numbers become great enough, or the food sources become scarce enough, so that the existing ranges reach their carrying capacity. Servheen said he doesn't have any firm numbers for the capacity of an area since there are so many variables involved.

The road to delisting

In March, the new "final conservation strategy" report for the grizzly bear in the Yellowstone area was released, including statement management plans for Idaho, Montana and Wyoming. It's an integral step in the effort to take Yellowstone grizzly bears off the list of endangered species, but Servheen cautions that it will be a long process.

"Delisting is still several years away," Servheen said. "We haven't even started to consider it. Our objective right now is to get to the point where we could propose delisting.

"The Forest Service is putting habitat standards into their forest planning, and we'll be doing an evaluation of the status of the Yellowstone population for the next year or so."

He adds that even though the conservation strategy was adopted in March, it still needs to be signed off on by numerous state and federal agency representatives. Servheen expects that alone will take about a year.

"So we could look at delisting of the Yellowstone grizzly in the next two or three years, if everything falls together. But the other populations would remain listed," Servheen said. "And once the population is delisted, it's not like we just walk away. We have a system in place to monitor the number of bears, the number of females, the number of cubs, the number of mortalities, the number of human conflicts.

"If there was a decline in those values, those would be investigated and we could respond accordingly. We could even relist the bear in two weeks if we had to.

"But the objective is to get the Yellowstone bears to the point where they could be delisted."

Not everyone wants to see that happen soon, though.

Merrill notes that even though more grizzlies now exist in the lower 48 states than did 25 years ago, it's still nowhere near what their numbers were a few centuries ago. The deciding factor as to whether the bear survives, or thrives, is the rate that humans kill bears. That's why he believes they need to be protected, not just by being on the Endangered Species list, but also by having their habitat protected - without roads, homes or natural resource extraction.

"The thing that facilitates humans killing bears, primarily, is how many humans are in the landscape, and how much access they have into good bear habitat," Merrill said. "The bears are not recovering. They may have some expanding populations, but the grizzly bear as a species is not recovering."

What most people do agree upon, though, is that there is no one solution for the grizzly recovery effort.

"The solution isn't about a wilderness bill, oil and gas leasing, subdivisions or one stretch of road. It's a cumulative problem, and because of its nature there is no one solution. It's a combination of things that we need to do - on a local, county, municipal, state, federal, national and even international level - that can make the difference," said Louisa Willcox with the NRDC.