Island Serves as Lab for Wolf, Moose Study Isle Royale National Park

Peter Rebhahn / Green Bay Press-Gazette / July 4, 2004


ISLE ROYALE, Mich. - It was the wildness that attracted Rolf Peterson to this Lake Superior island 34 years ago.

He stayed for the science.

"When you realize what goes on here in terms of the predator-prey relationship - there's no other place like it," Peterson said.

What goes on outside the door of Rolf and Candy Peterson's cabin that doesn't and can't elsewhere is intimate study of the dance of predator and prey in a natural laboratory nearly as perfect as any designed by humans.

Wolves are the predators and moose are their prey. The laboratory is Isle Royale National Park just 185 miles north of Green Bay, one of the most remote and least-visited of the nation's national parks.

It's not easy to get to Isle Royale because it's separated from the nearest mainland - it's closer to Canada than the United States - by 15 miles of frigid Lake Superior water.

Because of its isolation, the island is home to just a third of the mammal species that live on the nearby mainland.

Isle Royale's isolation makes it ideal for the study of animal populations because it's almost impossible for animals to come and go. Genetic study has confirmed that the wolves and moose on Isle Royale are all descended from the first immigrants, Peterson said.

Because it's a national park, no animals are hunted.

Biologists believe wolves walked across lake ice to Isle Royale around 1950, Peterson said. Moose are thought to have arrived earlier, probably around 1900, by swimming from the Canadian mainland.

There are only two eyewitness accounts of moose swimming in Lake Superior between Isle Royale and Canada. It's a trip that would kill any human who tried it without a wet suit. Few other mammals could withstand the cold water.

Why would a moose risk it?

The answer - a mixture of science, philosophy and humor - is typical of Peterson, who's nothing like the stereotype of the lab-coated scientist.

"Only people ask questions like that - moose don't," Peterson said. "There's a small percentage of any animal population that will do crazy things like that. It's like bungee jumping."

The research project Rolf Peterson now leads is in its 45th year - the longest continuous study of either wolves or moose anywhere.

About 750 moose live on Isle Royale today, down from 1,100 two years ago. "Right now the moose are going down and the wolves are going up," Peterson said.

Moose populations since Isle Royale research began have ranged from a high of 2,000 to fewer than 500. There are 29 wolves living in three packs on the island today.

Much of what researchers have learned about moose on Isle Royale has come from the study of bones. The research team finds about one-third of all dead moose within two years of death.

Study of the bones has yielded much information. In bad winters as many as 30 percent of all the island's moose die. Half die at age 10 or younger. Nearly all older moose suffer from arthritis, some severe enough to cripple.

Peterson, 55 years old and a professor of wildlife ecology at Michigan Tech University in Houghton, has been part of the Isle Royale study for 34 years, spending summers on the island and returning to Houghton during the academic year.

He's assisted by a team of researchers that includes volunteers and Candy, his wife of 33 years.

Candy Peterson relishes her self-assigned role as hostess to the students, reporters and curious tourists who discover the tiny and primitive 1926 cabin the Peterson's call home in the summer months.

"We have people every year that just wander in," Candy Peterson said.

Visitors are likely to be offered coffee, cinnamon bread and conversation. Candy Peterson, a self-described child of the '60s, graduated from Wellesley College with a degree in economics.

But she'd rather talk about nature than interest rates.

"If you leave Isle Royale and you haven't had your faith in yourself and your fellow man restored, you need to come again, because that's the message of this place," she said.

Candy Peterson said she misses the community life she leaves behind in Houghton each spring. Leaving behind the comforts of civilization gives her a twinge she said it takes her 15 minutes to forget.

"Who needs indoor plumbing?" she said.

The Isle Royale research has two major themes besides the effects of wolf predation on moose populations: wolf genetics and the wolf-moose-vegetation interaction. "They're more inbred than any other wolf population we know of," Peterson said.

How the wolves continue to thrive despite their lack of genetic variability isn't clearly understood. But the effects of the moose on the island's vegetation are easily spotted.

Moose prefer to eat deciduous plants, but there's not a lot of them on the island. Mountain ash, a favorite food, almost has disappeared from the island.

"They're doing the best they can on really meager food resources," Peterson said. "If April doesn't bring spring, these moose are in dire trouble, and the most vulnerable ones won't survive."

Rolf Peterson said he knows the day will come when age and the rigors of working in a wilderness will overtake him. But he doesn't plan to stop anytime soon. The science is just too tempting.

"This is the first time when we have the chance to see what happens when people keep their mitts off," Peterson said.