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Saving One Island's Wolves

Saving One Island's Wolves

Population crisis tests National Park Service's policy to avoid human intervention.


Image credits:

John and Leah Vucetich

Thursday, June 5, 2014 - 21:00

Joel Shurkin, Contributor

(Inside Science) -- The wolves of Isle Royale are dying.

One of North America's unique communities of gray wolves is disappearing, the result of inbreeding, human bureaucracy, and climate change. If the wolves go, a unique forest ecosystem could go with them.

It's a classic story of what happens when the leading predators of an ecosystem are removed. While the problem is easy to solve, the whole story also is wrapped in a major philosophical dispute over if and when humans should intervene in natural processes.

Isle Royale is the largest island in Lake Superior, part of the multi-island Isle Royale National Park. The island, 45 miles long and 7 miles wide, technically is in Michigan, although it is closer to the Canadian province of Ontario, separated from the mainland by 15 miles. It has no permanent human population.

Some 17,000 visitors journey to the island by ferry or sea plane when the park is open, from mid-April to mid-October. They backpack into the boreal forest, or kayak or canoe in the clear cold lake.

That the island has any large animals at all is because Lake Superior sometimes freezes in the winter. When it does, an ice bridge forms connecting the island to the mainland. Sometime at the turn of the 20th century, moose crossed the ice bridge and set up a growing population, peaking at 2,499 in 1995.

In 1949, a pair of wolves arrived and set up a pack that preyed on the moose, eventually driving the population of the moose down to about 500. If left alone, the wolves and moose would have reached an equilibrium.

Fifty-six years ago, the Michigan Technological University, in Houghton, set up a study of the relationship between the two species. It is still one of the longest, and most respected wolf surveys in the world. In the report published this spring in the journal Conservation Genetics, the scientists reported the number of wolves now was down to nine in two packs, and, without predators, the number of moose had doubled to 1,050.

Counting the wolves is fairly easy, according to John Vucetich, associate professor at Michigan Tech, who along with his colleague Rolf Peterson, runs the survey. A few wolves have radio collars and can be tracked from the air. Since wolves collect in packs, spotting one wolf means there are sure to be others nearby. The researchers also collect feces, enabling them to do DNA testing.

The problem appears to be that climate change has greatly decreased the occurrence of ice bridges, cutting the island wolves off from others. Only two bridges have formed in the last 17 years. One formed last winter but the only wolf to cross it went from the island to the mainland, where it was shot and killed by someone with a pellet gun.

The result is inbreeding.

In 1997, a lone male crossed from Ontario. Named the Old Gray Guy by scientists, he mated with two island females. He died in 2000. Every wolf left on Isle Royale descended from him.

In 2012, and for the first time in their history, the Isle Royale wolves failed to produce a single pup.

Now, one of the packs doesn't produce pups at all. The other pack produced three pups last year and none this year, according to Vucetich.

It could be that the island wolves refuse to mate because they are too closely related. Perhaps they do mate, but are infertile, or produce pups that die off before they can reach maturity and be counted, Vucetich said. No one knows for sure.

However, "there is very, very little doubt that the wolves are doing poorly and that inbreeding is a very important part of that," Vucetich said.

While the wolves have languished, the moose population has exploded, endangering the island's forest of fir and birch trees. The moose are eating the balsam fir on the island before it can grow into the forest canopy.  After a time, that will destroy much of the forest, he said.

It's a climate change issue, Vucetich said, and a question of whether to intervene in protected areas.

The U.S. Park Service, which controls the island, has so far refused to intervene by flying in a few wolves from outside the islands to refresh the gene pool, which Vucetich said can probably be done for less than $20,000. Even bringing in one wolf would make a great difference, as Old Gray Guy proved.

But the Park Service is reluctant to intervene in what should be a natural process.

"The decision is not to intervene as long as there is a breeding population," said Isle Royale National Park Superintendent Phyllis Green in a statement. The service has begun a study that could take three years, Vucetich said. But the wolves may not last that long.

While most biologists are generally comfortable with non-intervention, the Isle Royale wolves may be an exception.

Marc Bekoff, a retired professor of ecology and environmental biology at the University of Colorado Boulder, and a leading opponent of interventions in natural systems, said the Isle Royale case has made him rethink his position.

While climate change is affecting many animal populations, the island wolves are unique because of their isolation.

"I'm coming down on the side that rescue is pretty needed ... I'm thinking this may be one of those situations we need to do something," Bekoff said.


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Author Bio & Story Archive

Joel Shurkin, photo by Abigail Dunlap

Joel Shurkin is a freelance writer in Baltimore who has also taught journalism and science writing.