J. A. Vucetich / www.isleroyalewolf.org

Fall of the wild: The trapped wolves of Isle Royale

Global warming is putting wildlife at risk, leading to hard questions about wilderness ethics

Topics:
Michigan
Climate Change
Science

On January 21, Isabelle, a 5-year-old gray wolf, was spotted along the southwest reaches of Isle Royale National Park, which sits on an island in Lake Superior. During a survey flight over the island, John Vucetich, an ecologist with the Isle Royale Wolfe-Moose Study, confirmed the lone wolf’s identity thanks to a reading from her radio collar. “As we circled Isabelle, every few moments she stopped and turned to look back, as though concerned about being followed by other wolves,” wrote Vucetich on his research blog. During the previous year, two other wolves in her small pack had tried to kill her more than once.

Isabelle being chased by another wolf from her pack on Isle Royale.
J. A. Vucetich / www.isleroyalewolf.org

“They beat [her] up several times, the female who was to breed [with Isabelle’s brother] would not want another breeding female around. There were times we weren’t sure if she would survive. We would see her laying on the ice and were not sure if she would get up,” explains Rolf Peterson, wolf expert and a retired professor at Michigan Technological University who, with Vucetich, has spent the past 44 years studying the wolves and moose of Isle Royale National Park.

Yet, she did get up and made it on her own through the summer and fall. She fled the island and traveled across 20 miles of ice. But by February 8, Isabelle was dead. Her carcass was discovered on the shore of Lake Superior in eastern Minnesota, on the Grand Portage Band of Lake Superior Chippewa reservation.

According to the necropsy report, a pellet entered Isabelle’s chest and led to fatal trauma and bleeding. Whoever shot her multiple times with an air gun and left her for dead didn’t realize — or just didn’t care — that Isabelle’s arrival on the mainland had given her a second lease on life.  

The bridges of Isle Royale


Isle Royale locator map

Source: MODIS image processed by SSEC, University of Wisconsin, Provided by GLERL CoastWatch. Reporting by Mary Catherine O'Connor.

Isabelle’s long-term survival on the island was unlikely, and not only because other wolves ostracized her. Isle Royale’s once-robust wolf pack appears to be trotting toward extinction. From 2011 through 2012, the island’s wolf population declined 56 percent, and it has remained at its lowest total, just eight or nine individuals, since the Wolfe-Moose Study began, in 1956.

When an ice bridge, the only conduit between the island packs and the mainland wolves, formed during this past, frigid winter, Peterson and Vucetich felt buoyed with hope. During the first decade of the study, an ice bridge formed during three out of four winters. But during the past 17 years, because of rising temperatures, ice bridges have been documented only three times. One formed in 1997, followed by an 11-year gap. This winter marked the first bridge since 2008.

Rising water temperatures and declining ice cover in Lake Superior (the National Oceanic and Atmospheric Administration found that by 2011 the lake’s yearly ice coverage had declined 76 percent, compared with 1973 levels) have combined with strong winds to reduce the frequency of ice bridges connecting the 45-mile-by-9-mile island to the mainland of Ontario and Minnesota. Because of this, the last time a new wolf entered the island was in 1997, and that male bolstered the island’s “gene flow.”

Within a decade, however, all wolves on the island carried that new arrival’s genes. Today, the nine wolves that live on the island are all closely related. With most organisms, including wolves, this sort of genetic inbreeding reduces the rate of reproduction, and it is the major factor behind the Isle Royale population’s decline.

Another cold winter in the next few years could create another bridge and perhaps draw wolves from the mainland to contribute to the gene pool. However, it is impossible to say how long the current wolf population can survive in these conditions. Given the specter of extinction, Peterson and Vucetich want to transport mainland wolves to the island.

Their hope is that intervention, which scientists call genetic rescue, would result in a more viable wolf population. That decision, however, is not theirs to make — it falls under the purview of the superintendent of Isle Royale National Park. And it is a decision fraught with controversy and disagreement, both on scientific and philosophical fronts.

Isle Royale National Park is protected under the Wilderness Act, a seminal and eloquent law designed to ensure that parts of the American landscape would not only be free from development, but would remain wholly “untrammeled” by human activities and interference. Some wilderness advocates, including Kevin Proescholdt, conservation director for the Montana-based Wilderness Watch, say genetic rescue of the island’s wolves would violate these protections.

“We can’t ignore what ‘wilderness’ means,” he says. “When you look at the [legal] definition, it really prohibits us from manipulating wilderness ecosystems in the way that Rolf [Peterson] would like to do.”

In the past, park managers have manipulated wilderness ecosystems. The reintroduction of wolves into Yellowstone National Park, starting in 1995, is a perfect example. In that case, human intervention was considered to be “righting a wrong,” because humans had killed the wolves that previously occupied that landscape. Peterson argues that the “wrongs” associated with man-made climate change are clear, compelling and direct enough to argue for human intervention on Isle Royale. 

wolves
Wolves chasing moose on Isle Royale.
J. A. Vucetich / www.isleroyalewolf.org

Michael Nelson, professor of environmental philosophy and ethics at Oregon State University, says it’s time to start thinking more critically about the wilderness ethic. He has studied the writing and correspondences of the founders of the wilderness movement, including ecologists Aldo Leopold and Olaus Murie.

In the mid-1940s, Leopold and Murie proposed transporting wolves to Isle Royale in order to control the island’s huge moose herd, which, lacking any predators, had been going through major boom-bust cycles since colonizing the island (also via the ice bridge) in the early 1900s. Moose numbers would grow quickly thanks to the island’s ample vegetation and then, as food sources like the balsam fir were over-browsed, the moose would suffer from malnourishment and have low breeding success. Once the population fell precipitously, the plants would regain a foothold and moose numbers would grow along with that recovery — until they grew too much and the boom-bust cycle restarted. Adding a predator, such as wolves, to the ecosystem would keep the moose numbers from booming and, therefore, would keep vegetation levels stable.

Ultimately, Leopold and Murie — who had convinced the National Park Service to bring wolves to the island —did not need to intervene. Around 1949, at least two wolves came onto the island of their own accord and found there a feast. During the decades in which this predator-prey relationship has been studied, the wolf and moose populations have grown and shrunk in response to each other. Now, with wolf numbers shrinking, the moose population has doubled over the past three years. Without the predator to keep it in check, moose would likely re-enter boom-bust cycles.

“I think there are going to be times — and there probably always have been times — where human intervention might promote ecosystem health, and it might also protect the ability to have something that we would call a wilderness,” says Nelson. “There is no demand on us to be wise or prudent when you just equate wilderness with nonintervention."

Not all wolf experts are in accord when it comes to what, if any, intervention should be done, and when. David Mech, U.S. Geological Survey senior scientist, thinks there is still time for the animals to rebound on their own. “We’ve been crying wolf on Isle Royale for a long time now,” he says, referring to research papers that express concerns over extinction, dating back to 1989. “I think the most valuable thing we can do for scientific purposes is to just watch the situation. If we had [done genetic rescue] when claims about declining packs were first made, in 1989, there would be lots of good science that we would not have, because anything learned after an introduction would not have been based on a natural population.”

Wolves crossing the ice bridge that connects Isle Royale to the mainland
Wolves crossing the ice bridge that connects Isle Royale to the mainland
Rolf Peterson

Indeed, some geneticist are keen to learn how the genetic depression exhibited in the inbred wolves on the island — many have spinal deformities and at least one appears to be half blind — plays out in the future. Others back a third option: waiting until the wolves are unviable but not extirpated, comprising only males or females, and then perform genetic rescue.

“The scientific implications of these present wolves recovering — and that, in my opinion, would be a population of 20 to 30 wolves — if that were to happen without new genes coming that would be remarkable. It would go against decades of genetic understanding,” says Peterson. “So, yes, it would certainly be important if it happened, but expecting it to happen would be a pretty big stretch.” 

In early April, Isle Royale National Park announced it is creating a management plan for the island’s wolves — which will propose a course of action that takes into account the health of the island’s moose and vegetation. The proposal will include an environmental-impact statement describing the background, wilderness policies and preferred and alternative courses of action. The process will likely take three years — a time plan that Vucetich says amounts to a decision to not pursue genetic rescue, since by then it could be too late to save the wolves.

Isle Royale superintendent Phyllis Green says her job is to consider the likely impacts of climate change on not just the wolves but the entire island ecosystem. Even though the moose population is currently robust, some studies point to trouble for them as their favored vegetation shifts north because of rising temperatures. Boosting wolf numbers — assuming that the introduced wolves are welcomed and begin breeding — might compound the moose’s problems. “We have to consider trade-offs between resources and species. We need to know how we define success if we intercede with nature,” she says.

Isabelle in the woods of Isle Royale.
Isabelle in the woods of Isle Royale.
J. A. Vucetich / www.isleroyalewolf.org

Wilderness advocates like Proescholdt worry that if parks begin to respond to the effects of climate change with actions such as genetic rescue, they will start down a slippery slope of interventions that could ultimately degrade wilderness character. On the other hand, across the National Park system a great swath of biodiversity is at risk due to everything from invasive species to catastrophic wildfire to a rise in sea-level — conditions humans have exacerbated, in many cases, through climate change.

Vucetich says it is more important to evaluate each case of intervention based on the costs and benefits, guided by an overall objective. Introducing new wolves on the island would be a low price to pay — about $20,000, and it would likely need to be repeated every 20 years, assuming no more ice bridges form — in order to keep the island’s ecosystem in balance. He says that is more affordable than more audacious interventions that have been proposed elsewhere, such as irrigating giant sequoia trees in Sequoia and Kings Canyon national parks.

If the objective is to keep our hands off wilderness, no matter what, the choice seems clear. On the other hand, Vucetich says that if the goal of a protected area is to maintain its ecosystem health, “doing nothing, as Isle Royale National Park has elected to do thus far, represents an unnecessary risk.” In the end, when it comes to addressing climate change in wilderness areas, he says, “There is no pile of scientific facts big enough to tell you what should be done.”
 

The last remaining wolf pack on Isle Royale.
Rolf Peterson