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What should be done to save Isle Royale wolves? Maybe nothing, experts say

The appearance and disappearance of species — even those we come to see as signature species — are a part of natural order, especially in island environments.

The wolf population trend on Isle Royale for the last six years has been steadily downward.

About 100 people gathered last night to hear a panel of four experts discuss what should be done to bring Isle Royale’s wolves back from, quite possibly, the brink of extinction.

Many seemed surprised to hear three of the four presenters suggest that the best answer may be, nothing at all.

Phyllis Green, superintendent of Isle Royale National Park, framed their presentations by making clear that all options are up for debate — nonintervention, letting the wolves die out and then  reintroducing them, or attempting some form of “genetic rescue” (adding new wolves to a population whose inbreeding has created weaknesses, most notably a  spinal abnormality).

Green made clear that park managers’ discussions are in the earliest phase, with a formal decision-making process to begin towards fall. The park has already convened a panel of experts to talk about the genetics aspects of the issue, and expects to receive the work of another panel examining climate change impacts on the island park in about a month.

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But she may have indicated some of her own thinking by underscoring Isle Royale’s “spectacular isolation,” which has made it interesting to scientists in the same way that the Galapagos seized Charles Darwin. It’s a place, she said, where species are constantly disappearing (caribou and lynx in the early 1900s, for example, with a type of cisco about to follow them into history),  while others are appearing (a tricolor bat, certain tree frogs) and still others are becoming genetically distinct from populations elsewhere (pine marten, a blue garter snake).

Historical perspectives on species

Tim Cochrane, the superintendent at Grand Portage National Monument, opened the panel presentations by extending that line of thinking back through history. The reality, he said, is that even the species we care most about are continually appearing and disappearing from particular places, and the situation of Isle Royale  — where wolves suddenly appeared in 1948 or 1949, to prey on huge herds of moose that themselves were absent before 1910  — is not so unusual.

Woodland caribou and Canada lynx were plentiful on Isle Royale for long periods ending in the 1920s, he said; coyotes were resident until the 1940s. (The lynx population was so large in the early 1900s, Green told me after the talk, that trappers were taking 50 a year.)

Wolves are thought to have come to the island via an ice bridge from Lake Superior’s north shore; Cochrane pointed out that they also appeared in the Slate Islands of eastern Lake Superior in the 1990s, he said, presumably having crossed over the ice, but didn’t stay long.

Moose were not plentiful anywhere  in the region before intensive logging in the mid-1800s cleared the land of big white and red pines, opening up better brush-browsing opportunities for them. (The moose were also assisted by copper mining operations that simply burned away the forests to expose ore bodies at the surface.)

Cochrane mentioned, too, an old story suggesting that moose may have been brought to the island initially by people who wanted to hunt them there and suggested, in answer to a question, that the apex predator with the longest historical tenure on Isle Royale is not, in fact, the gray wolf but our own species, which used it as a hunting ground for caribou for 4,500 years.

“What is ‘natural’ on Isle Royale is a dicey question,” he said, and “whether wolves ‘belong’ on the island is an open question.”

Returning the island’s species balance to its longest running iteration, he said not quite seriously, would require letting the wolves disappear, assigning hunters to take out the moose, then reintroducing woodland caribou and lynx.

Can they recover on their own?

David Mech, a biologist with the U.S. Geological Survey who began his half-century of wolf study on Isle Royale, assigned himself the role of critiquing the notion that Isle Royale’s wolves are in any particular danger of disappearing, and argued that any action in their behalf is premature.

The eight wolves counted in this past winter’s survey is not necessarily a number that signals the brink of extinction, he said. After all, only two are needed to reproduce, and the island’s wolves have already shown their ability to recover from a previous low point of 12, back in the 1980s, a decline brought on by canine parvovirus brought to the island in a pet dog.

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If anything, he argued, the recent drop in wolf numbers is the expected consequence of an earlier drop in the moose population.

As for disease factors, Mech said that mainland wolves cope well with canine parvovirus (which seems to be on the rise again in Isle Royale wolves) until the infection rate goes far higher than what’s been seen on the island. And he suggested that the lumbar-sacral spinal abnormality seen in Isle Royale wolves, known as LSTV, also occurs in about the same proportion in mainland wolves.

 (Rolf Peterson, the longest-serving director of the wolf-moose studies on Isle Royale, said later that while the 60-year prevalence of LSTV  may be about the same in Isle Royale and mainland wolves, all wolves born on the island since 1994 have had it.)

As for climate change, Mech said that while warming temperatures may be making ice bridges a rare occurrence, it’s also possible that shifts toward weather extremes could, over time, create more ice bridges. In which case, wolves from Minnesota’s recovered population stand ready to make the trip.

“We have cried wolf for 25 years” about their disappearance from Isle Royale, Mech said. “Let’s just wait and see what happens!”

Sanctity of wilderness

Kevin Proescholdt, a lifelong advocate for the Boundary Waters canoe wilderness now working for Wilderness Watch, argued against any intervention.

The wilderness designation that covers 98 percent of the park’s land mass, he said, is the highest and most protective status available for federal lands and is rooted in a philosophy of nearly absolute restraint from manipulation.

In the words of Howard Zahniser, credited with drafting the Wilderness Act of 1964, “we should be guardians, not gardeners” in these special places, and “we should let Isle Royale itself choose its own course into the future. “

Alongside this philosophical argument, Proescholdt pointed out that if wolves do indeed “blink out” on Isle Royale, that doesn’t mean the end of an ecosystem nor even the end of scientific investigation into island ecology.

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And he joined Cochrane and Mech in cautioning that intervention isn’t necessarily a one-time choice, but rather a first step down a slippery slope of perpetual manipulation.

A case for intervention

The single voice raised in behalf of intervention was Rolf Peterson’s, and he acknowledged that his own thinking has changed in recent months.

For a long time, he favored letting nature take its course with the current wolf population  — and if that course led to extinction, reintroducing fresh wolves selected to avoid a repetition of the inbreeding problem.

Now, however, he has become concerned by forest impacts of the burgeoning moose population in recent years, when wolf predation has essentially fallen to zero. Reintroduction or genetic rescue will take some time to restore a healthier wolf population, he said, with undesirable consequences for both the moose herds  — which will soar and crash — and the balsam fir forest, which itself could teeter on the edge of ruin.

On the western two-thirds of the island, where moose browsing is heaviest, firs rarely grow more than two or three feet tall. If they can survive to about 9 feet, they can survive the moose, and if they can get to about 12 feet, they can reproduce.

“Some of these trees have been waiting for 60 or 70 years” to outgrow moose browsing, Peterson said, and large sections of the fir forest had their first chance in a century to actually reproduce and expand.

That opportunity is disappearing with the latest crash of the wolves and concurrent soaring of the moose herd. A longer-term disruption of the moose/wolf balance might  erase it indefinitely, Peterson said.

This is not a new concern. In the 1940s, influential ecologists including Aldo Leopold argued for introducing wolves to Isle Royale to save the forest from being stripped away by moose. Before they could act, a female and one or two males volunteered for the job, crossed the ice and started the island’s first wolf packs.

Peterson acknowledged that the eight surviving wolves could indeed recover, as Mech suggests, but he thinks it’s unlikely because of the genetic problems. And their last notable recovery, from a low point of 12, owes its ultimate success to a volunteer “genetic rescuer”  — wolf No. 93, also known as Old Gray Guy, who crossed the ice from Canada in 1997 and quickly dispersed fresh DNA throughout the island population.

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After the talk I asked Phyllis Green  if she knew of other places where this same issue  — whether or not to intervene in federal wilderness areas, in behalf of species conservation — is being considered within the park system.

She said there has been some talk, preliminary as yet, of whether  extraordinary steps will be needed to conserve certain mountain species that are being driven to higher altitudes by climate change, until “sooner or later you run out of mountain.”  Island environments of another kind, you might say.

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Last night’s program was organized by the National Parks Conservation Association and the Sigurd Olson Environmental Institute at Northland Collge in Ashland, Wis., and moderated with deft aplomb by Nancy Gibson of the International Wolf Center.