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A photo of a wolf on Isle Royale.

The number of wolves on Isle Royale National Park (pictured, an animal in 2008) have dwindled to just nine animals.

PHOTOGRAPH BY ROLF O. PETERSON

Christine Dell'Amore

National Geographic

Published April 27, 2014

The call of the wild in northern Michigan's Isle Royale National Park may be losing one of its voices: that of the gray wolf.

In 2009, scientists documented about 24 wolves living on this remote, forested island in Lake Superior (map). But as of February 2014, that population has dwindled to nine—the second lowest total ever recorded, according to the Wolves & Moose of Isle Royale Project, which calls itself the longest continuous study of a predator-prey system in the world.

Map of wolves.

The reason for the decline is likely inbreeding. Because there's so little genetic diversity among the remaining wolves, all the animals have skeletal deformities, and their weakened state could be interfering with reproduction: Only three pups were born in 2013.

Scientists say inbreeding has become more of an issue because the ice bridge that often connected mainland Ontario, Canada, and Isle Royale in the winter no longer predictably forms, due to steadily rising temperatures in the region. So wolves from Canada are rarely able to cross the bridge and bring new genes to the existing pack. (Last year's unusually cold winter did produce an ice bridge, and one wolf that left the island was shot by a hunter on the mainland.)

The changed landscape presents scientists with a dilemma. Should they intervene to save Isle Royale's wolves, or let nature take its course?

Wolves are relatively recent arrivals to the island, which has hosted a changing constellation of wildlife over the centuries. The populations of beaver, moose, fox, and other animals there are constantly shifting. And although wolves are considered endangered in other parts of the country, they aren't in Michigan. (Read "Wolf Wars" in National Geographic magazine.)

On April 9, the U.S. National Park Service made its stance clear: The agency will not take any immediate action to bring wolves to the island.

"We think there's enough issues and questions that are unanswered that we need to take a much closer look at it," Isle Royale National Park Superintendent Phyllis Green told National Geographic.

The park came to its conclusion after reviewing the best available science and the benefits to the public, Green said. "In reality what we come back to is finding the right juxtaposition between law, science, and the long-term stewardship of the island." (See: National Geographic's profile on Isle Royale.)

The Park Service decision doesn't sit well with some scientists, including Rolf Peterson, a wildlife ecologist at Michigan Technological University in Houghton who began leading the Isle Royale wolf-and-moose study in the 1970s.

The common notion that we should "let nature take care of herself and not be meddling presumes that Mother Nature is intact," Peterson said.

"But we started cutting off her fingers some time ago."

A photo of wolves on Isle Royale.
A pack of wolves travel Isle Royale National Park, which is located in Lake Superior, in 2005.
Photograph by Rolf Peterson

Genetic Rescue

Instead of taking a hands-off approach, Peterson believes that a few wolves from the mainland should be released on Isle Royale—a strategy called genetic rescue.

Wolves first showed up on Isle Royale in the 1940s, when a handful crossed the ice bridge from Ontario just a few decades after moose had made the same trek. The research study examining the relationship between predator and prey began in 1959. (Watch video: "Wolf Hunting Tactics.")

The research found that when new wolves crossed the ice bridge and joined the existing population, their fresh DNA invigorated the packs, leading to a healthier ecosystem, Peterson said.

When a new wolf appeared in 1997, for instance, the rejuvenated population hunted more moose in the following decade than ever before. Now the wolves are hunting very few moose, and with fewer predators, the moose population has doubled in the past three years, to more than 970.

The antlered herbivores are poised to quickly eat through the 206-square-mile (534-square-kilometer) island's balsam fir and other vegetation, presenting yet another problem for scientists.

"There's a mythical belief that Isle Royale has been working well because we kept our hands off it," Peterson said. "In my opinion, it worked well because there were wolves there."

A photo of a wolf inspecting a dead moose on Isle Royale.
A wolf inspects the carcass of a moose—one of its main sources of prey—on Isle Royale National Park in 2009.
Photograph by Rolf Peterson

Inbreeding Overblown?

Yet L. David Mech, a senior research scientist with the U.S. Geological Survey who conducted the first three years of the Isle Royale study, argues that the population may not be as badly affected by inbreeding as Peterson asserts.

He said there's no proof that inbreeding has affected the ability of the wolves to survive, pointing out that they did produce pups in 2013 and are still killing moose, albeit fewer.

"I had argued it's always been inbred," said Mech, because the original population "was founded by one female and one or two males."

What's more, the global trend of climate change brings with it unpredictable extremes, such as more severe storms, that could create longer lasting ice bridges. (Related: "New Climate Change Report Warns of Dire Consequences.")

"That makes me more inclined to continue to say, Let's just watch the situation and see what happens," Mech said.

He also believes the scientific knowledge gained by observing the events on Isle Royale is extremely valuable and that intervention "corrupts the value of the whole study."

For instance, he said, if scientists had intervened and introduced wolves in 2013, "we wouldn't know if the animals that are left could reproduce." The new pups that year proved that they could.

Richard Thiel, a retired wolf expert at the Wisconsin Department of Natural Resources, said he's on the fence about whether to introduce wolves to Isle Royale.

But he does see value in what he calls Mech's "argument for letting the system go." If wolves did become extinct, he said, "it would be interesting to see in X amount of years what happens to that system."

Thiel noted that though the Park Service has historically adopted a wait-and-see management approach, the agency has made bold decisions to reintroduce animals before, including wolves to Yellowstone National Park, starting in 1995, and black-footed ferrets to Badlands National Park, also in the 1990s. (See: pictures of wolves in and around Yellowstone.)

Whether that was a success depends on whom you ask. The Yellowstone environment is undoubtedly more robust, but wolves that leave the park are often killed by hunters or ranchers, Thiel said. That's "part of beauty of NPS properties and part of the bane: How do we manage these ecosystems, and what should be in them?"

Isle Royale's Phyllis Green said the agency is "trying to look out for the system for the American public for the long term." For instance, the park attracts nature and animal lovers, offering 155 campsites in the summer. (See National Geographic's suggestions for best hikes on Isle Royale.)

"it's important to hear [from] the full range of folks—there can be a lot of passion when you hear about wolves," Green said.

A photo of a wolf on Isle Royale.
A wolf crosses a snowy plain on Isle Royale in 2010.
Photograph by Rolf Peterson

Inevitable Extinction?

The experts differ as to whether the wolves will survive if left alone. Mech believes they might. Thiel said he's "losing faith that there's long-term resilience in there."

"Small populations such as this simply can't beat the odds," he said.

Mike Phillips, who was a field biologist on Isle Royale in the 1980s and is now executive director of the Turner Endangered Species Fund, went further, saying that the wolves' "extinction is inevitable—it's only a question of when."

Not only are the animals inbred and marooned without regular ice bridges, he said, but fragmented populations of animals are also generally more prone to go extinct.

Phillips described what might be a sort of win-win situation for the park: Let the current group of wolves die out, for the benefit of science, and then immediately restock the island with wolves from the mainland, so that the ecosystem can bounce back.

"The [National Park Service] could stop the drama by issuing one statement: 'We will promote studies through extinction and shortly thereafter reintroduce wolves,'" he said.

The agency did say in its April 9 statement that "if the island population of wolves declines to all males or all females, and if the moose population grows to overbrowse island vegetation, bringing wolves to the island remains an option."

Phillips is convinced that "a lot of good science" could come from boosting the population with more wolves and "monitoring to see how new genes can be used to bring vigor to the population."

Such observations could also have global import: Many species are becoming smaller and more isolated due to climate change and human disturbance. The fate of the Isle Royale wolves could "give us an idea of what populations around the world are headed for," Phillips said.

Wisconsin's Thiel agreed: "We can watch them blink out, and reconstruct that whole thing, and use [it] as a predictive tool for other places where species are having trouble."

Complicating the debate, he said, is the fact that nature itself is never static, so it's difficult to say that wolves should be on the island.

"We know in our heart of hearts that natural ecosystems are always changing," he said. "The ideal state is in itself elusive."

Unique Place

One thread seems to unites all of the people who've worked on Isle Royale: Their love of a unique, uninhabited park, one that's hard to access but that gives visitors an unsullied wilderness experience.

"One of the draws of Isle Royale has been that there are wolves there," said Thiel. "It's so fascinating to walk through an area that's not touched by humans. You can't find any place like that in North America, even in Yellowstone."

He added, "If you're lucky, you roll over in your sleeping bag in the middle of the night and hear the wolves howling." (See "Wolves Identified by Unique Howls, May Help Rare Species.")

How long that will remain possible is unclear.

Follow Christine Dell'Amore on Twitter and Google+.

66 comments
Drew Lohmeyer
Drew Lohmeyer

I think that we should let nature play its course and if the wolves go extinct then we need introduce more wolves into the island.

Robert Gordon
Robert Gordon

There are only 9 wolves left on Isle Royale, suffering multiple health problems from excessive inbreeding. Meanwhile the moose population, with a declining predator base, is growing at 20% a year. Within a few short years the wolves will be gone, the moose population will explode and then collapse as they eat the island out of house and home. The National Park Service contends man should not interfere and let nature take its course. This ridiculous policy conveniently ignores the long history of mans involvement at Isle Royale through mining, fishing, tourism, and the palatial National Park Service headquarters. Contact the National Park Service and tell them you support genetic repopulation by adding a few new wolves to the pack before it is too late!

Lynelle Ladd
Lynelle Ladd

It was a course of natural action that wolves and moose migrated to Isle Royale and man should not interfere now. A single breeding pair of wolves started the population, inbreeding has always been a factor. Humans should not interfere. If left to their own devices, and the opportunities posed by nature, the wolves could die off, or maybe they will take an opportunity to cross the lake during a freeze and leave the island for good on their own. Maybe other wolves will decide on their own to go to the island in search of prey or mates?  If the remaining population de-populated the island on their own, would man be so righteous in his "knows what's best" attitude to recapture them and take them back to the island?  I would hope not.


The island has allowed a unique opportunity for scientists to study wolves and maybe that opportunity's time is up, leaving a new opportunity for scientists to see what happens when prey are left without a predator to keep it in check.


Man needs to start by managing himself and his impact on the environment (pollution and overbreeding/over-population of humans), and then maybe as humans we wouldn't have to worry so much about how the other animals are responding to nature. 

Harry Moutzalias
Harry Moutzalias

Let nature take it's course. Wolves have only been on Isle Royal for 50 years. They're trapped there and putting more wolves their would be cruel. 

Bill Le Voir-Barry
Bill Le Voir-Barry

Animals are the natural extension of the human race. Many need protection, before they are wiped out due to ignorance. In the United States, the Grey Wolf is one such species that is on the “run” again for its survival. Please go onto MoveOn and read, and if inclined, please sign my petition. Search by the words: States are Reckless – Please put Grey Wolves Back on Federal Protection List

Jennifer Trench
Jennifer Trench

Yes we should save and help ensure the future of the wolf pack on Isle Royale by strengthening the gene pool.

Joao Mendes
Joao Mendes

I do believe that positive human intercession is necessary in this case, as long as negative human intercession in the past led to the present situation.

H. Dragneel
H. Dragneel

Well, I don't really understand the problem that introducing new wolves supposes... If what makes the number of wolves to decrease is the unmixed genes, then just put another wolf there and hope it's accepted by the pack, am I wrong? I don't understand the problem then

Eden Hamer
Eden Hamer

I agree, humans should just let them do their thing.

we have already changed their lives for good so  lets not do it again



chritine rompella
chritine rompella

as like so many others out there agree with one thing as humans we do more harm in thinking what is the right thing to do is helping matters when it comes to down to it makes things wore in the long run. as for me i think we should do whatever it takes to help the wolves.

Leigh Rohrer
Leigh Rohrer

Replace the two wolves that died after falling into a mine shaft built by man not nature and I am sure there are other instances of wolves dying because of human interference on Isle Royale so the point of letting nature take its course becomes mute.

Talia Wys-Nichols
Talia Wys-Nichols

To say "let nature take its course" is naive. We have already interfered with nature by creating the climate issues that have caused the land bridge to be unpredictable. Respect for nature has been lost so now to say nature will handle it is a cop out. We need to do whatever we can to help these beautiful animals, not just sit back and watch their demise....

William Harmer
William Harmer

Save the wolves no matter what anyone says they are a important part of life if we don't save them that just makes us look unhumane an then y don't they kill all of us to

Kayla Wolfdog
Kayla Wolfdog

Nature should be left to take it's course. Chances are, the remaining Wolves on Isle Royal will not survive. If that is the case then the Park Service should take a look at what they want to do after that happens.

Kayla Wolfdog
Kayla Wolfdog

Nature should be left to take it's course. Chances are, the remaining Wolves on Isle Royal will not survive. If that is the case then the P   aaaaaark Service should take a

Lori H.
Lori H.

If this is a safe environment with plenty of land and game then you are damn straight we should get involved!  Sanctuaries with wolf populations always have pups that will need placement.  If it's known that there is a wild environment for them they can be handled accordingly while being raised.  We should NEVER give up!  Humans are taking away habitats constantly-here you have one and you just want to let it go?  Really?  For SHAME!

Rita Woodward
Rita Woodward

Possibly, with the harsh winter that has hit the North Americas this year - nature has taken a hand to the issue.

Karen Holther
Karen Holther

I am from Michigan and I've been a fan of the Isle Royale wolves since junior high school.  I would like to see the existing wolf population augmented in a capture/re-release program, live-trapping some wild wolves from a region that is overpopulated and releasing the females onto Isle Royale to see if they will breed with the males there.  You can't observe nature without affecting it.  This is a park:  Let's manage it.  There's no good in pretending that we're outside of nature, looking in.  We have our own part to play in ensuring healthy outcomes.  Whether we restock the park or not, it will always be a valuable area for population studies due to its geographical isolation. 


P.S. - Because wolves are pack animals with complex family dynamics, I appreciate the difficulty in getting new wolves to mix with the ones already there.  I question if introducing new males would be productive or not, due to the likelihood of violent conflict; that would be a question for the geneticists and animal behaviorists to ponder.  My gut feeling is to try introducing new females only, and see if the males already on the island will pair with them. 


Best wishes to all Isle Royale students & well-wishers!  This subject has given me a lot of pleasure & satisfaction over the years.

John Hall
John Hall

I hate the thought of a group of beautiful animals dying out like this.

Why not repopulate the wolves and doing so control the problem of moose over populating. 

Everyone was quite happy when the wolves crossed the ice bridge to ensure a new gene pool, so without the bridge lets transport the wolves ourselves.

dayna mattis
dayna mattis

why is it we try to save every other animal ? SAVE THE WHALES !!! SAVE THE MANATEES!!!! Why not save the wolves then too ? They are beautiful and majestic creatures that deserve saving !!! After all, isn't it humans that have made them near extinct ????

Alexandra V.
Alexandra V.

That makes me sad, humans should interfere!! we can help and try to change their destiny , we have a part of responsibility in this so let's help them out !! :)

Matthew Horns
Matthew Horns

Isle Royale has been a natural laboratory for more than a half century. During that time wolf populations have rebounded in the Lower 48. In my home state of Minnesota they have repopulated areas where they have been gone for decades.


In my opinion, I believe that Isle Royale should continue to be a natural laboratory without human intervention.

If the wolves perish, it would be great to see under what conditions they repopulate the island.


If the moose overpopulate and become short on food resources, it would be great to see how the moose survive.


Nature is brutal for wildlife. Let's not let Bambi Syndrome ruin this unique natural laboratory.

William L Reyna Jr
William L Reyna Jr

If the National Park Service can't/won't do the job, perhaps some "outside" help is needed to ensure the genetic diversity of Isle Royale.

If you want something done right sometimes you have to do it yourself.

Cose Vidal
Cose Vidal

Save the wolves. It's quite tiring to hear about this "let nature take its course" thing but we save humans when nature could otherwise kill them.


Save the wolves, because if we interfered to kill one when it tried to come out of there, we could also interfere to help them and keep the balance between pray and predators.

valerie homer
valerie homer

Yes we should do everything we can to help them survive

Lily Sullivan
Lily Sullivan

Genetic rescue is the way to go! Once the moose and other prey destroy the Park's woods and lands, it will diminish the Park's beauty as well as destroy the other population of animals dependent on the wolves checks and balances.

Michele Scott
Michele Scott

So how can people say "let nature takes it course" when humans are the main issue with the changing environment, humans are changing nature, so if we are changing nature should we then intervene to try and repair some damage, why wait until they are extinct to do something, it's too late then!!!, too me all issues stem from humans over populating the earth and pushing and driving animals to extinction.

Vonne Pitcher
Vonne Pitcher

Why are Americans still shooting wolves when their numbers have been declining for years?  Will they ever grow up and appreciate other life forms.

Of course you should help these isolated wolves before they all disappear.  What's wrong with building some sort of bridge from the island to the mainland then let nature take its course?  Seems logical to anybody else.

Eugenie Szwalek
Eugenie Szwalek

Nature has a way of balancing everything out on it's own, sometimes it is just best to wait and see how things play out. If the population of wolves on the island is really suffering from inbreeding, then it might be best to simple let nature take it's course. You never know, a new predator or other environmental factor may come into play and take the place of the wolves. I do love wolves, they are my favourite animals, but sometimes it's better to let thing unfold on their own and simply watch and learn from the outcome.

Shannon Bernardo
Shannon Bernardo

I believe genetic rescue is the right thing to do. It is a National Park where the wolves can thrive with a little help from the creatures that have screwed up the environment causing their plight in the first place.

Terri Bocklund
Terri Bocklund

I vote for genetic rescue.  Without wolves (and without human intervention) the island would need years, perhaps decades, to regain an environmental balance (which nature can surely do without our help).  But, if we want to continue to call Isle Royale a National Park and not a chunk of basalt covered with rotting moose carcasses, we'd need to be willing to leave it alone, and I mean REALLY ALONE, for a good long time.


I was an Artist in Residence at Isle Royale last summer.  If you'd like to hear my music about the future of the Isle Royale wolves, you can listen free at https://soundcloud.com/terribocklund/wolf-song.  Feel free to get in touch.  


Terri Bocklund

Jeff Schimpff
Jeff Schimpff

Interesting contrast to just 7 years ago: http://www.sciencedaily.com/releases/2007/03/070310153004.htm.

The most scientifically useful course seems to be to allow the current wolf population to become extirpated (not extinct, for their genetic make-up lives on in Ontario and Minnesota packs), study the continuing changes to all ecosystem components, and then later decide whether to reintroduce a viable new wolf population.

It would be useful to expand this current story to fold in the changes that have occurred since 2007.

J. Griffin
J. Griffin

Of course people should intervene! That would be horrid if they were left to just die out.There is no "benefit to science" when it involves living beings dying! At the very least build a permanent bridge or tunnel for the wolves to travel to the mainland.

Christine Dell'Amore
Christine Dell'Amore

Thanks for the insightful comments everyone! Adrian Piers, I didn't get into it in this story but there is concern about parvovirus—if you go to the wolf-and-moose study's main website you can find info about it. 

claud pipkin
claud pipkin

Sure, why not?... They reintroduced them into Yellowstone didn't they..............They need to find the core reason for their decline however

Seraphina S.
Seraphina S.

there are many reasons for the decline in the wolves but that does not mean we should step away from the mess we have caused. Introduce new wolves to the area, or introduce the wolves to a different area with sustaining food supply and a couple of other packs. Watch them and make sure they adapt and if needed interfere.

Gary Conn
Gary Conn

This, the least visited of all National Parks in the U.S., Isle Royale is vulnerable from every trepidation. 

On Isle Royale, the decline of wolf population is well documented and has been for some years.  

Kyle Hineman
Kyle Hineman

Of course we should try to save this population. All this conversation about "stepping in" or " letting Nature take it's course" is ridiculous.

We certainly didn't hesitate to step in and exterminate them by the millions when were were pioneering this country. That wasn't natural and this inbreeding isn't from natural causes.

 It's just another sign of our rampant destruction of everything that doesn't turn a profit.

Adrian Piers
Adrian Piers

Have genetic samples been taken to make comparisons to mainland wolves? What are the effects of canid diseases carried there from domestic dogs?


Here in Africa we the the Ethiopian wolf that is found nowhere else. Observations of these wolves on the Island may give us some insight into how to conserve this species. 

Robert Gordon
Robert Gordon

Quite the opposite. The current policy is cruel to the marooned wolves confining then to some sort of genetic inbreeding hell. Adding a few wolves now would expand the gene pool and quickly solve the problem.

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