Six to eight wolves will be trapped in Minnesota and Michigan, then flown to Isle Royale this fall, as part of a grand natural experiment in returning the top predator to the wilderness island in Lake Superior.

Four of the animals will be trapped at the Grand Portage Band of Chippewa reservation in northeast Minnesota and two others will come from Michigan, officials from the National Park Service said Friday as they detailed the first phase of an effort to re-establish wolves as a means to control the rising number of moose on the island. Eventually, they hope to establish a population of 20 to 30 wolves.

It's the first time the National Park Service has tried to pre-empt natural dynamics in order to reset the ecological equilibrium in a wilderness area, which by federal designation is to be left largely untouched by human hands. But after years of review and debate — and a decade of declining wolf numbers — Park Service officials said intervention was the better choice to prevent overpopulation and eventual starvation of the island's moose.

If the effort succeeds, it will open a new chapter in the long and fascinating saga of wolves and moose on Isle Royale, a story that's been documented for decades by research scientists from Michigan Technological University.

Now the wolves' largely secret lives will be much more visible to the world, thanks to GPS collars that each animal will wear once released. More than ever, they will become the focus of biologists observing their activities in a closed ecosystem: How fast they pair up, form packs, interact and kill their first moose.

"There is a great deal we can learn," said David Mech, a wolf researcher with the U.S. Geological Survey and an adjunct professor at the University of Minnesota.

Rolf Peterson, the Michigan Tech scientist who's been studying Isle Royale's wolf-moose dynamic, said in an e-mail Friday that he heartily approves of the reintroduction plan and hopes to expand the scope of research that's been underway for decades.

The first pair of wolves arrived on the island in the 1950s, most likely via an ice bridge that had formed from the mainland. They became the founding pair for a population that eventually peaked in the late 1970s at about 50. But inbreeding, disease and accidents have gradually reduced their number to the two that are left today — a father and daughter who share the same mother.

The number of moose, however, has risen steadily, to about 1,500, and they are overeating firs and aquatic vegetation which is their main diet. Eventually, they could starve, creating a boom and bust population cycle that is typical of island ecosystems.

A healthy wolf population would stop that.

"We look forward to witnessing this unfold, following along as the wolves make the island their new home," said Lynn McClure, regional director for the National Parks Conservation Association, a nonprofit park advocacy group.

Park Service wildlife officials said they plan to capture wolves over the next six weeks, using leg-hold traps and expert trappers from the Grand Portage band and the federal wildlife service of the U.S. Department of Agriculture.

They are seeking an equal number of young, healthy adult male and female animals to maximize the chances that they will mate and produce pups.

"We want to ensure we put a population of wolves on the island that is not only genetically variable but also has the right experience" in hunting large prey like moose, said Mark Romanski, chief of natural resources for Isle Royale National Park.

Once captured, the wolves will be sedated and screened for parasites and diseases. Weather permitting, healthy ones will be flown to the island on an amphibious plane within 24 hours of capture and immediately released.

The wolves will be distributed to different parts of the island to minimize conflicts with each other and with the two that are already there. Nonetheless, conflict is inevitable, said Seth Moore, natural resources director for the Grand Portage Band.

"I would not expect to see a high rate of survival," Moore said. His research on the moose and wolves that live around the Grand Portage reservation, some of which are collared, shows that the average life span of a wolf is one to three years.

It will take repeated efforts to bring more wolves to the island in coming years to ensure success, he said.

The band is eager to participate in part because the project extends its interest in wildlife management to the island, which was at one time part of its tribal territory, he said.

Phyllis Green, park superintendent, said officials also hope to get permission from the government of the province of Ontario to capture two more wolves this winter, somewhere on the northern shore of Lake Superior. That will increase the genetic diversity of the new population as well.

The entire plan, she said, depends on capturing healthy wolves and on the notoriously wild weather on Lake Superior this time of year. The project will resume next fall, she said.

The capture process also holds some risks for the wolves.

Romanski said other similar efforts show that, on average, 3 to 5 percent of wolves can die during capture from hazards such as anesthesia or injury.

Two captured wolves died during their transfer to Yellowstone National Park in the mid-1990s, one when the anesthesia dart entered its heart, and the second months later when it was illegally shot outside the park.

Mech said that previous relocation projects have shown that adults who are mated or members of packs have powerful homing instincts, often making it a futile effort unless they are moved at least 80 miles.

"They have a compass," he said.

It's even possible that wolves transferred to the island could initially attempt to swim back to the mainland, putting them at risk, he said.

But if they stay put, he said, he gives the experiment a good chance of success. Once settled into their new home, he said, the wolves will do what wolves do — mate, have puppies, and kill moose.

Josephine Marcotty • 612-673-7394