Isle Royale’s Wolf Population Dwindles to Three

Photo: Gary Kramer/ U.S. Fish and Wildlife Service

Three wolves on an island: these are not good odds for long-term survival.

The wolves of Isle Royale National Park – an island on Lake Superior – constitute one of the most iconic predator populations in the world.

And according to latest reports, only three of them remain.

Eighteen months ago, I wrote an essay on the fate of Isle Royale’s wolves, pondering whether new wolves should be introduced to bolster a population that then stood at ten. The piece was one of the most controversial we’ve published on Cool Green Science.

Since then, the news for the wolves has only gotten worse.

According to ecologists at Michigan Tech, the population now includes a male, a female and a 9-month old pup in deteriorating condition. And that’s it.

What does the future hold? Three wolves is not a viable population. But the larger conservation issues – whether wolves should be reintroduced, how moose will be managed – remain for conservationists to decide.

Here’s the issue in a nutshell:

The wolves arrived on Isle Royale in the late 1940s, likely via an ice bridge. The dynamics of moose and wolves on the island became the subject of the longest running predator-prey study on earth.

In the 1980s, a virus introduced by a visitor’s sick pet decimated the wolf population. It recovered, but now inbreeding has brought the population to the brink.

Due to climate change, there were fears that new wolves would not be able to recolonize the island via an ice bridge, because ice bridges occur infrequently in warming winters.

This winter was actually a cold one for Lake Superior, and an ice bridge formed. Two wolves indeed ventured to the island – but they quickly left. Unfortunately, they didn’t breed with the existing wolves, either.

What to do next raises all sorts of interesting conservation science dilemmas.

As I noted in my original piece, in many ways what has happened to wolves mirrors what often happens to wildlife species on islands: they come and go. This is what ecologists call island biogeography.

In the 1800s, there were not wolves on the island. Nor were there moose. Historically, there would have been lynx and caribou – both no longer present.

New species continue to arrive on the island, including a bat and several amphibians.

But, as critics of my essay correctly pointed out, this is not a case of “natural” evolution on the island. The caribou and lynx disappeared due to human activity. Wolves were dealt a huge blow from an introduced virus. Human-caused climate change influences the ability of new mammals to reach Isle Royale.

“One must use the word, ‘naturally’, carefully these days,” says Rolf Peterson, the longest-serving director of wolf-moose studies on Isle Royale. “The human imprint is written all over the dynamics of this wolf population in recent decades.”

Peterson and others also emphasize that one of the important considerations is the cost of losing an apex predator. A hyper-abundant moose population could cost more to manage than the costs associated with reintroducing wolves.

The moose population has been increasing at a rate of 22 percent per year for the past four years. That could cause significant ecological damage to the national park. And it’s certainly due to the absence of wolves.

Should wolves be reintroduced immediately? Or should biologists wait until the population disappears and reintroduce an entirely new pack? The National Park Service is researching options, but that decision could take years.

What if the wolf population follows this pattern – flourishing for a bit and then dwindling after 40 or 50 years? Is that a good use of conservation resources? How many wolves would be necessary to avoid inbreeding?

Ultimately, I concede that Peterson is right: “letting nature take its course” on Isle Royale is, at this point, impossible. The heavy hand of humanity has been felt there for a long time, and will continue to do so in the future.

But that fact still does not direct conservationists what to do next. What do you think? What should the future of Isle Royale look like?

Join the Discussion

Please note that all comments are moderated and may take some time to appear.


  1. Matt, thank for revisiting this topic. As one of the commenters to the original piece who preferred reintroduction, I am glad to see an evolution in your thinking. Wolves are under attack in many western states. Giving a new population a home in this protected setting would be a plus for ecology, for wolf numbers in general, and for the enjoyment of Isle Royale’s visitors. Let’s do it!

  2. A true observer makes adjustment to positions as new evidence is presented. Matt, Thank you for having an open mind on the role of humans at Isle Royale.
    I too wrote in on the previous mentioned article. In that time the wolf situation has become more dire and the moose population continues to grow. In 11 consecutive years on Isle Royale I have seen firsthand the effects on the forest as the moose population increases. Without a top predator the ecosystem will be severely damaged and we will have a repeat of the winter of 1996 when the last mass die off of moose occurred. At the current rate of increase this could happen rather soon. The park service should encourage the addition of new wolves to the ecosystem. Waiting for a politically acceptable solution is not wise. The application of the wilderness act standard of no intervention is not appropriate at Isle Royale. This is a case were man can and should intervene. The benefits are many to the ecosystem, specific species the visitors and the educational power of the entire wolf moose study. It’s impact is vast.
    Bring breeding age wolves to Isle Royale. Do it soon!

  3. In every debate a dissenting opinion is necessary and mine will be that opinion. Yes a human-introduced canine virus decimated the population on Isle Royale and could certainly be used as an excuse to introduce a new pack of wolves to the island. But how can we be sure that this is the ‘right thing’ to do? Two wolves traveled over this past winter and decided not to stay – what do they know that we don’t? Almost certainly they were aware of other wolves on the island and knew that they weren’t worth joining. Maybe this die off is exactly what should happen to the pack and in a few years a new pack will make its way back to the island. Until then we’ll have to tolerate the moose issue (a 1996 type population plunge will almost certainly occur) and eventually the island will reset itself. Let’s not over-react to this situation.

    1. Apparently there is no need to “be sure” as we slaughter tens of thousands of predators and other animals through agencies such as Wildlife Services.

  4. Isle Royale is a designated wilderness. I suggest you look at the problem from the management principles set out in that mandate because that is the reality. I rarely hear the term come up in any Present debates about the fauna presently extant within the Isle Royale wilderness. That’s troublesome to me. You begin with the Wilderness Act of 1964 and proceed into the debate from there. Yes Isle Royale has been profoundly affected by humans, that’s not intellectually very difficult to derive. What’s apparently hard to fathom for some is the fact that those affects will be guided by the legislation that the National Park Service is mandated to follow. Land management is a legal process. You want to debate it, then tailor it to that process and nothing else.

    1. It’s hard to imagine any wilderness area that is totally lacking in top predators. Historically, natural systems had suites of top predators. I question your priorities.

      1. Indeed it is. Predators come and go from the Isle, as they always have. I miss the Pleistocene dire-wolves that once must have prowled it’s high ridges and low-lands at the close of the last Ice Age. We should bring them back too. Why cherry-pick?

        Law isn’t a priority, law is just adhered to no matter what. NPS management has to adhere to public land law to direct their management actions. There’s nothing really there to question. You just do as your told. We can debate biological scenarios all day long and pine for this predator or that predator, or this ecosystemic arrangement or that. I all makes for intriguing and dramatic copy. At the end of the day NPS has to manage Isle Royale via many a Congressional mandate and I’m sure they will. What I’m saying is, debate the predator-prey, ecosystemic conditions and desired conditions at Isle Royal all you need to… just debate them inside the framework of the Wilderness Act.

        And all the rest.

        That’s how public lands are managed. You start from the laws and policies first, then proceed into the emotional, professional and philosophic debates.

        There will be both law and predators at Isle Royale. The laws are constant… the predators, whatever species, come and go.

        As they always have.

        As they always will.

        1. Perhaps the new predators will be red wolves? Chasing all those frisky white-tails? Playing out their lives within that new warm-loving, oak-dominated, broad-leaf forest ecosystem that’s “a-comin round the bend” pretty soon?

          Or I should say… coming up from the south?

          Let’s not forget the possums and raccoon.

          Either way, there will be some kind of predator showing up with the new climate regime. Which one though?

          1. Or the coyote, the North East is flush with them. I wonder how many coyote it would take to take down a moose…

  5. I’ve wondered, in reading through these pages and posts, whether two (or is it three?) wolves is enough to bring down a moose?

  6. I just read the article after returning from the Up, where i have a small cabin. I have not made it to Isle royale yet but will soon. In regards to the issues of introducing a few wolves to augment the current three there I propose the following:
    Since man made effects such as climate change, men killing predators who once lived there such as the lynx, and also caribou, and the introduced virus, i feel strongly that a few wolves should be introduced. This would alleviate a mass die off of the wolves over the next couple of years and preserve the unique environment.
    As the island is somewhat of an environmental lab for researchers to observe a microcosm of the full environment we should intervene and bring in wolves to save the predator population , the balance between prey and predator, the environment as well as a slow death for the moose through over breeding.

  7. Just hearing about this from the Minnesota Zoo, felt like I needed to state my opinion. I believe that letting nature take its course won’t be very effective and introducing wolves right away would put a gamble as to whether or not they would get along.
    I believe that one possible solution is to select a group of healthy wolves that would be able to be moved to Isle Royale. The existing 3 wolves on the island should be taken off the park and placed in a location or holding area where they can see each other but not get in contact with. They would need to be able to get along with the other wolves. The same method is used with breeding big cats, endangered animals, and even reptiles (which makes me believe it could work).
    Once the wolves can be calm in front of them, they can get progressively closer and eventually go into the same area. They would again be moved back to Isle Royale and be kept under extremely close surveillance. Careful considerations to be made with this is to also keep a close check on the moose population…which brings me to my next point.
    Naturalists/Conservationists would need to find an area such as Alaska, Canada, or another national park where the wolf-moose population is in an equilibrium. Of course, it would be preferable if the location had a similar environment and climate as Isle Royale. A ratio must be found with the population of wolf and moose in the location and must be incorporated to fit in with the environment and climate of Isle Royale. The method of introducing the wolves to more wolves must be repeated and the hunting/relocation of moose must be made to fit in with the ratio of wolves and moose. This method would certainly take quite a while but if it so happens that it would have the possibility to work out alright or not work at all, then so be it.

  8. I was fortunate to travel to Isle Royale with 4 of my high school students in the early l990’s. Three
    of the four have returned to the island since. I hope to go to this park soon.

    Its so sad about the issues with the wolves. I m still wondering about those men who brought dogs
    to the island and spread parvo-distemper there. It would help if they would come forward and show
    their remorse and perhaps lead a fight to get this moose/ population balance stable again.

    Like a lot of people, I am so tired of the politics of the way things are and believe they should introduce
    health wolves back into Isle Royale. They came over in l944 by accident and I see nothing wrong with
    doing the “act of God” and bring some into the park again.

    Why are the so called environmental experts dragging there feet here? We introduced wolves to Yellowstone and its time to wake up and get wolves back into the park. I also see no reason why
    we can t at least in the short term have so “kill hunts” by members of the Park to bring down a few
    moose each year to keep their population limited.

    What is the correct balance. I m not sure but I ll guess that if there were 2 or 3 packs of wolves the
    moose population could become a healthy 2000 of so. Love to see someone move forward on this
    and I m sure if enough teachers and students can join this movement, WE CAN DO SOMETHING


  9. I have another comment about this Isle Royale debate. I consider myself a life-long learner and lover
    of our environment. All my life I have traveled across the USA and into several National Parks and enjoyed nature and all the adventures of backpacking, canoeing and camping. I have one big question
    for all “you current naturalists”.

    Why is everything about climate change and global warming. As Russ Limbaugh said once: “We
    now know the cause of global warming—-its called JULY “. That is so true and I for one am so sick
    of people spreading all these lies and tales of what is happening around the World.

    Let me speak to some of you with some common sense thoughts. Do the two terms weather and climate
    having the same meanings? And does anyone ever go back in time and read about the history of weather and storms? There are so many examples of droughts, heat-waves, flooding, and storms at the turn of the last 2 centuries with accurate records. ***please stop telling everyone that we are getting more storms and the degree of damage is more than every. Talk to your grand-parents or great-grand parents
    and listen to how they too saw big storms and had heat spells and terrible weather too.

    We all know that data can be used and turned around to express your agendas. The polar bear is not
    endangered and those pictures are doctored to scare little grade school kids. I m so sick of all this crap and we all know that climate is constant but weather changes daily and within hours the conditions can change. In the USA it will always be cold and perhaps snow at Christmas time and on July 4th the climate
    of the southern states is very hot and yes—–the snow has melted in Alaska. Stop this silly debate.
    The term weather and climate is NOT the same word or meaning!!!!!!

  10. I am a frequent visitor to the island in all its wonder. It is my opinion necessary to help the balance by introducing a breeding age pair of wolves and maybe a couple more in 5 years. Humans have created a world that species can’t sustain in themselves. If we do nothing, weare condemning them to a date of death and extinction.

  11. Mr Miller:
    I read with interest your story on the declining wolf population on Isle Royale. I have spent numerous summer vacations hiking the many trails on the island, marveling at the sheer magnificence of God’s natural world. From the rugged topography, to the splendid views that are displayed throughout the park, I have come to understand, to some degree, the delicate balance that exists between man and creature. I have often witnessed the relationship between moose cows and calves as they work to survive and thrive in the wild; yet I have never seen a wolf on the island. I had heard, just a few short years ago, that the three packs then in existence were roaming ever further away from their traditional hunting zones and straying into more areas of human activity. Now to read this devastating news is monumentally sad. To imagine that only three animals remain on the island does not seem remotely possible. yet I trust the numbers and wonder myself, “what is the right thing to do?”
    I am however a bit troubled by the often one-sided debate regarding “man-made climate change” or as you word it, “human caused climate change” which in the opinion of many, is bad science exacerbated by anecdotal evidence, which is neither scientific nor unanimous. Is our earthly climate fluid? does it ebb and flow over generations? Of course; history bears this out. It seems an easy leap for many to jump onto this liberal bandwagon to explain every evil that exists in nature. Likewise, mankind’s history of defiling the earth for profit or personal gain is evident as well. I do not exist, or think, in a vacuum. I realize the stewardship we are all called to bear when conserving and preserving the only world we have. Yet it is never as easy or definable as some would make it out to be.
    Your article fails to point out the positive wildlife management that has been on-going at Isle Royale for decades. How many people and institutions have dedicated their efforts to the future success of the wolf and moose populations? Sometimes nature turns on itself, it is not always a cause and effect relationship. We cannot always know why? To simply blame the “human imprint…” on the proliferation or the demise of a species is short sighted and unfair. It’s complicated, knowledge is ever evolving, so conclusions are, at best, premature. If one does not write to an agenda, one might be able to write to the problem, suggesting solutions, offering honest evaluations, and reporting what we know to be true.
    What is different from an ice bridge migration or an intentional re-introduction by conservationists? Wolves have been re-introduced in Yellowstone with great success. What are the alternatives? Do nothing; wait for the next ice bridge to form; or intentional re-introduction. Just as the Lynx and the Caribou have long since departed Isle Royale, so too may the wolf and the moose. The prey/predator relationship should not be artificially manipulated for our sake, but for the benefit of the animals in question. We should learn from what has already been successfully implemented elsewhere, and use this knowledge to make the most informed decision we can, based on what we know today.
    Thanks for your interest and your article.

    Respectfully, Doug Bennett

  12. Currently doing a very large study on this in my 9th grade Biology class. Your articles are really helping me with my understanding and assignments! As for the conservation, the popular vote in my class seems to be the introduction of new wolves or the idea of ‘letting nature take its course’!

  13. Matt

    I lived in Michigan for several years and very much appreciate the ecology of Isle Royale. The island I currently inhabit has no wolves or moose but a couple of snow leopards and 1.6 million people. I would love to see Isle Royale restored to a reasonable and sustainable balance. Let me know if I can help.


    Frank Folz

  14. I met Mr. Peterson and his wife when I visited Isle Royale for a kayaking trip in 2008. I believe at the time there were three packs of wolves. This was the beginning I believe when both moose and wolf populations had started to change for various reasons. Weather and fights between packs was suspected.
    Although I was unable to see any wolves and only one moose on my paddle it was a deep feeling of knowing what the dynamics of the island were. Therefore I would agree with Rolph and support new introduction of wolves to be introduced soon before the moose population is decimated also. This would create a new chapter of study.

  15. From time immemorial man has managed these lands. The evidence is all around you if you will look beyond your text books. Open your eyes to who not what taught Aldo Leopold. Who did he marry and who were her ancestors.

    Today the students of Isle Royale and Nature’s way are recreating Isle Royale in Alasks and thereby devastating Alaska wildlife resources. Alaska, under their watch, has lost more than 90% of its wildlife harvest in your lifetime. Alaska’s national parks have lost more. To the point that Alaska is now the least productive wildlife habitat in the nation.

    Alaska historically exported and imported billions of tons of biomass annually through its rivers to and from the oceans. In three generations that bounty has fallen 95%. As a result both the oceans and Alaska have suffered.

    One is reminded of one of Winston Churchill most memorable quotes. “You can always count on Americans to do the right thing,….after they have tried everything else.”

    Can Alaska wait that long? Can the oceans?

    Isle Royale has become Alaska’s Typhoid Mary and the patient is dying.

    The only question remaining is whether or not any student of Isle Royale has the ethical courage to tell the truth in time to save Alaska or will the lies of Isle Royale be Alaska’s tombstone.

  16. Dear Matt Miller
    Do what it takes to make things right, man is the one who needs go into a decline as my grandfather said on the farm in Texas the world is changing he saw it and I wounder what he saw and the events that followed made me really be leave him now I am 64 now . If I could do something then as a child I would its going to be to late now that the A”” H ,,,, who is going to be psdt. DO your best. make it right.

  17. the real question should be is this for the wolf or for the biologist that is going to lose his research project?
    the study should come to a conclusion when the last wolf dies.
    ask the biologist what new information they have come up with in the last 5, 10 .20 years in the isle royal wolf study and the answer in nothing, not a f#$king thing. there is no use putting more wolves there to die a slow death.