Wildlife

Wolf – Caribou Detente? Clues Hidden on Lake Superior Islands

A woodland caribou peers through spruce trees on Lake Superior’s Slate Islands. (Photograph: Andrew Silver)

Qalipu, it’s called by Canada’s Mi’kmaq people. To others, it’s the elusive gray ghost of the far northern forest. Most know it simply as caribou.

Woodland caribou are medium-sized members of the deer family. In Canadian provinces such as Ontario, these shadows in the forest are listed as threatened – quickly vanishing.

Non-migratory woodland caribou – one of two Ontario caribou “ecotypes,” with the other migratory – stay in the boreal, or spruce-fir, forest year-round. Most of Ontario’s non-migratory caribou live north of Lake Superior, but a few are found along the lake’s coast. Some are on its islands. Are caribou on the wane there, too, or could good news be hidden on these dark isles?

Recent scientific expeditions to the islands, especially 17-mile-long by six-mile-wide Michipicoten, offer reason for optimism. And clues to possible détente in what’s been called a running battle between predator and prey: wolf and caribou. 

Adult and pup wolf on Michipicoten Island, Ontario, Canada.
Trail cameras on Lake Superior’s Michipicoten Island capture a gentle game of tug-of-war between two wolves, one an adult, one a pup. (Photograph: Ontario Parks)

Caribou in the Balance

Researchers at the Ontario Ministry of Natural Resources & Forestry (MNRF) estimate the province’s woodland caribou population at 5,000 animals. Since the late 1800s, more than 40 percent of the species’ Ontario range has been lost, mainly from habitat fragmentation by human activities such as logging and mining. At the current rate of decline, woodland caribou may be extinct in Ontario by 2100, some scientists believe.

In 2014, a dozen or more researchers at Guelph and Trent universities, the Canadian Forest Service and the Ontario MNRF released results of a four-year Ontario caribou population study. The State of the Woodland Caribou Resource Report lists 14 caribou ranges. Of these, only the Lake Superior Coast range has slashes through it. The lines signal “discontinuous distribution”: few to no caribou.

A look offshore, however, tells a far different tale.

Woodland caribou approach a "salt lick" on Michipicoten Island.
Woodland caribou approach a “salt lick” – a spot where salt accumulates and attracts animals such as caribou – on Michipicoten Island. (Photograph: Andrew Silver)

Better Times for Caribou

More than a century ago in 1907, woodland caribou made their way across Lake Superior on a rare, eight-mile-long “ice bridge” from the mainland to the Slate Islands.

Today there are some 100 caribou on the Slates, according to Steve Kingston, a biologist at Ontario Parks. The number once may have been as high as 650. Then a severe winter in 1990-91 and a resulting shortage of caribou food such as lichen caused the dramatic drop.

Lichen species woodland caribou eat.
Favorite food of woodland caribou: Lichen that grow on and beneath trees in the boreal forest. (Photograph: Philip Wiebe)

A decade earlier in the 1980s, eight caribou were translocated from the Slates to Michipicoten Island, 81 miles to the southeast. “Today caribou are faring very well on Michipicoten,” says Brent Patterson, a biologist at the Ontario MNRF. He and colleagues conducted a survey there in February, 2015, and found that the island is now home to more than 300 woodland caribou.

Michipicoten Island in Lake Superior in winter.

Michipicoten Island’s rugged shoreline in winter. Ice bridges from the mainland to the island have formed in recent years. (Photograph: Brent Patterson)

Ice Bridge to Danger?

Long after the 1907 ice bridge, new frozen pathways reached the Slates – and transported more than caribou.

“The Slate Islands were free of predators,” says Kingston, “then ice bridges formed in the winter of 1994, and again in the winters of 2014 and 2015, opening passages for wolves.”

In January, 1994, a wolf was sighted on the ice next to Mortimer Island near the Slate archipelago. That spring, wolf tracks were recorded on Mortimer for the first time. “Signs indicated that two wolves were there,” Kingston says.

By the summer of 1996, one wolf had disappeared. The body of the second wolf was found in 1999. A necropsy showed that caribou did not make up the majority of its diet. Beavers were the wolf’s most frequent meals, but it also dined on snowshoe hares, red-backed voles, birds, insects and berries.

The frigid winters of 2014 and 2015 again led to the formation of ice bridges. Researchers soon confirmed the presence of three more wolves on the Slates. As of February, 2016, all three were still on the islands.

Researcher Brent Patterson with a radiocollared wolf.
Biologist Brent Patterson places a radiocollar on a wolf on Michipicoten Island. (Photograph: Bob Elliot)

A New Story

Wolves also found their way across the ice to Michipicoten.

A Michipicoten camper spotted two wolves in the summer of 2014. Months later, a naturalist photographed tracks of three wolves on a beach. The wolves likely made their way to the island in the winter of 2013-14, padding across an ice bridge that extended ten miles from the Ontario coast.

In February, 2015, Patterson and other researchers mounted their first expedition to Michipicoten. They found a pack of three wolves, two males and a female, and placed radio-collars on all three.

The signals showed that the wolves traveled together for most of that winter, says Patterson, “and snow-tracking evidence suggested that the larger male and the female bred on the island.”

Trail cameras the scientists mounted on Michipicoten trees revealed that by March, 2015, a fourth adult wolf had appeared. “We don’t know whether the fourth wolf was there all along, or if it crossed over on an ice bridge and joined the group later,” says Patterson.

In June, 2015, four months after the biologists’ initial trip to the island, they returned. During the harsh winter of 2014-15 only a few caribou were taken by wolves, Patterson says, “but many caribou died of malnutrition.”

The discovery may indicate that Michipicoten hosts more woodland caribou than its vegetation can sustain. “The poor condition of the caribou, along with very few sightings of cows with calves, suggests that caribou numbers have probably exceeded the island’s carrying capacity,” says Patterson.

“If the wolves preyed on caribou more often,” he adds, “conditions for the surviving caribou would probably improve. Caribou densities are high on the island due to the absence of predators for so many years. Fewer caribou should mean less competition for available food.”

In February, 2016, the team went back to the island. The biologists radio-collared the fourth wolf, an adult male, and located two pups. Ontario MNRF researcher Art Rodgers also fitted GPS tracking collars on 30 adult caribou. The scientists should soon have a handle on how the caribou are responding to the wolves.

Wolf pack on Michipicoten Island travels along a beach.
Michipicoten’s wolf pack travels along the island’s south shore on a November afternoon. (Photograph: Ontario Parks)

Species in a Complex Dance

What are Michipicoten’s wolves eating, if not caribou?

The island hosts a thriving population of beavers, an important food source for wolves during the ice-free spring-to-fall season – and in mild winters when ponds stay open, Patterson found when he again trekked to the island last month. “Like many other places this winter, there was very little snow and ice on Michipicoten,” he says. “Only a few caribou had been killed by wolves. Instead the wolves were likely eating beavers.”

Why would Michipicoten’s wolves hunt beavers when the island is awash in caribou? “Beaver meat has considerably more calories and fat per pound than caribou,” says Patterson. “Beavers are also probably fairly easy to catch, especially in spring and fall when they forage extensively on land.”

Wolves, beavers and caribou are in a complex dance on Michipicoten Island. Where will they wind up when the music stops?

“We don’t yet know,” says Patterson. “We’re just beginning to understand the interplay of these species.”

For now, Michipicoten, an Anglicized Ojibwe word for the region’s high bluffs, may spell hope for Ontario’s woodland caribou. And, perhaps, a newfound coexistence for caribou and wolves.

Wolf tracks on a beach on Michipicoten Island.
The tracks of wolves trotting along a beach on Michipicoten Island confirm their presence. (Photograph: Carol Dersch)
Science journalist and ecologist Cheryl Lyn Dybas, a Fellow of the International League of Conservation Writers, brings a passion for wildlife and conservation to National Geographic, Natural History, National Wildlife, BBC Wildlife, Scientific American, The Washington Post, and many other publications, and is a featured speaker on science journalism and conservation biology. Eye-to-eye with the wild is her favorite place to be.
  • Cindy Garhart

    The Caribou need the wolves. They will maintain each other’s species as long as they are allowed to do so.

  • Rose MCKENZIE

    Leave nature to sort its own eco balance in its own natural order as it has done for thousands of years without mans intervention. Proven to work. If nature was left alone in the first place we wouldn’t have all these problems.

  • Ashley Van Etten

    Very excited to read this article. As a child, my grandfather, Rosie Ellis, owned nearby Caribou Island and I was fortunate to spend time there. It’s an amazing ecosystem, relatively untouched by humans. At one time there were caribou, though long gone, and many beavers inhabit the inland ponds. Not sure if wolves ever made it that far. Thank you for bringing back many memories of family, adventure and wilderness.

  • Oliver Craig

    I agree let nature sort it out, in the long run this will be the best solution.

  • Lissa

    The hoesnty of your posting is there for all to see

  • Derek Carlson

    Interesting article. Given the history of moose, wolves and documented research on their interaction on an island ecosystem like Isle Royale, it’s not that surprising to read about wolves and caribou. However, beaver and wolves? Now that is something that is extremely interesting and I never would have thought beavers could be a primary food source. More research needs to be done.

    • Bryce

      Update. No more research needs to be done. Wolves are within weeks, maybe a month from eating the last of the Lake Superior Caribou to extinction. Trapped on an island with no escape and no room to hide in space it was only a matter of time. Who knew it would only take a few years. The wolves on the Slate Islands have now starved to death after eating all the caribou and there are only a few Caribou remaining on Michipicoten.

  • Bob McClelland

    We have fished for the last two summers on the slate islands. In 2016 we saw numerous caribou, however this year none. We encountered ministry personnel who were attempting without success to live trap and radio collar wolves. The local folks from Terrace Bay told us that some of the caribou had left the islands when the lake froze over.

    • Bryce

      I was planning on going next summer but it appears the last of the caribou have been eaten and the wolves have starved to death☹️

  • Kate McKulkin

    Wait, if this is the case, why are these animals within weeks of disappearing?

    The caribou in Pukaskwa are gone; the caribou on the Slate Islands nobody’s seeing — nearly gone, too; and on Michipicoten Island, with now 20 wolves and the Bergerud Criterion:

    https://doi.org/10.1139/z86-226

    … exceeded by a factor of >16, the caribou there will be gone within weeks. They’re down to less than 100 individuals. There was never any research here unless you’re into watching collar data come back as the last individuals of a species at risk disappear. Is that what you’re into? A random, meandering data gathering exercise with no meritorious scientific research question? Why is that happening in blatant disregard of Ontario’s Caribou Conservation Plan mandates?

    The “answer” was known all along — extirpation. Who approved this “research”? Did they know that any question regarding persistence versus extirpation was settled nearly half a century ago in the academic literature? See:

    https://doi.org/10.2307/3800042

    Oh well, it’s just a species at risk, right? It happened under our watch — under YOUR watch. Ooops! Gone….

    Check out LakeSuperiorCaribou.ca — but do it quickly.

  • John Benson

    The situation on Michicipoten Island provides an opportunity to gain valuable scientific understanding about aspects of predator-prey relationships that have eluded ecologists and wildlife managers for years. Although it seems clear that wolves have caused a major decline in the caribou population in the last few years on Michicipoten, this does not mean that wolves will necessarily drive caribou to extinction on the island. Nor is the recent decline in caribou numbers on the island necessarily a bad thing for caribou. Whether there were 450 or 700 caribou when the wolves first arrived on the island, they were clearly many more caribou than the habitat on the island could support. The densities on the island prior to wolf arrival were orders of magnitude greater than typically found in caribou populations elsewhere. Not surprisingly, some individual caribou observed by trail cameras in Michicipoten were in very poor condition. Caribou starvation is not nearly as common now as when the wolves first arrived; however, researchers and tourists who take the time to fight their way into Michipicoten’s interior continue to find the carcasses of caribou that died of malnutrition or starvation during the previous winter. Thus, wolf predation may be helping to bring caribou numbers back to sustainable levels and improve the physical condition of individual caribou.

    Those concerned about the extirpation of caribou on Michicipoten have been quick to cite research conducted in highly managed, mainland landscapes that is probably not directly relevant to the situation on Michicipoten. Wolf predation on ungulate populations has been studied on several islands, most notably on Isle Royale across Lake Superior from Michicipoten. Wolves were studied with moose on Isle Royale for approximately 60 years during which the highest moose densities ever recorded were achieved. A second example with many parallels to Michicipoten occurred on Coronation Island, Alaska (about half the size of Michicipoten). On this island there was an overabundant population of black-tailed deer in poor body condition that appeared to have exceeded the available food supply. Wolves were introduced to the island which led to a substantial decline in the deer population and improved the condition of individual deer. After deer declined, wolves shifted their diet to other sources and also killed and ate each other. Wolves ultimately died out on Coronation Island and the deer population rebounded and has persisted. We need to keep in mind that wolves and caribou evolved together so coexistence is the natural state, whereas caribou living free of predators as they have been on Michicipoten is definitely not natural.

    There is an opportunity here to learn important things about wolf-prey relations on islands regarding the demographic and behavioral responses of a formerly naïve caribou population to wolf predation. For instance, it will be instructive to analyze behavior of caribou that are killed by predation compared with those that escape predation to gain a better understanding of how caribou shift behavior in an adaptive manner relative to predation risk. Given the overabundant caribou population relative to its food supply, the island would also be an excellent location to investigate relationships between predators, prey, and vegetation. Overabundant caribou could be negatively affecting the structure of the vegetative community they rely on for food. This is what occurred with overabundant deer on Coronation Island mentioned above. There is great confusion about interactions involving multiple trophic levels which has been highlighted by disagreement among scientists regarding the influence of wolf reintroduction on potential trophic cascades involving elk, willow, and aspen in Yellowstone. The bottom line is that we do not know what will happen between wolves, caribou, and other species on Michicipoten. Effective and defensible wildlife management must be based on science and understanding. Allowing scientists to learn from the interactions between wolves, caribou, and plants on Michicipoten could provide that understanding. The hypothesis that wolves can be solely responsible for the extirpation of their prey remains untested. Should we enact interventionist management based on untested assumptions, or take advantage of this learning opportunity to facilitate implementing more informed and effective management in the future?

  • Leo Lepiano

    The situation on Michicipoten Island provides an opportunity to gain valuable understanding about how the Ontario MNRF approaches species conservation.

    Ontario’s 2007 woodland caribou conservation plan opens by stating, “Ontario will continue to be a leader in caribou recovery and conservation in North America.” Unfortunately this has not been the case, as populations have continued to decline and ranges have continued to recede: https://www.thestar.com/news/gta/2017/10/16/ontario-stumbles-on-caribou-protection-plan.html

    Caribou are very different than moose; they are not large enough to stand and fight against wolves, but rather rely entirely on evasion and avoidance, so comparisons to Isle Royale are falsely analogous. Caribou were extirpated by wolves from another Island on Lake Superior (Montreal Island), and tourists who visit the Slate Islands have said that they are not seeing any caribou there (there were also wolves on the Slate Islands).

    Michipicoten Island was home to a caribou population in the 19th century. It was extirpated by hunting in 1880. On April 20, 2017 the Minister of Natural Resources and Forestry released 500 brown trout (non-native species) into Mill Creek: http://kathrynmcgarry.onmpp.ca/Video

    Conservation relies on research. It also relies on setting clear criteria when research must give way to conservation efforts. While researching caribou on the Slate Islands, it seems – according to reports from tourists and scientists – that caribou have disappeared. The bottom line is that researchers must have plans in place for what to do when their research threatens to lead to the extirpation of a “threatened species” as well as the other animals involved (i.e. in this case, the wolves). Without having clear plans and thresholds for action, their research cannot be considered ethical.

  • Bryce

    Update. Sorry, they didn’t maintain. Wolves have now nearly eaten the last of the Lake Superior Caribou to extinction. Trapped on an island with no escape and no room to hide in space it was only a matter of time. Who knew it would only take a few years.

  • Bryce

    Update. Wolves are within weeks, maybe a month from eating the last of the Lake Superior Caribou to extinction. Trapped on an island with no escape and no room to hide in space it was only a matter of time. Who knew it would only take a few years. The wolves on the Slate Islands have now starved to death after eating all the caribou and there are only a few Caribou remaining on Michipicoten.

  • Bryce

    Update. Wolves are within weeks of eating the last of the Lake Superior Caribou to extinction. Trapped on an island with no escape and no room to hide in space it was only a matter of time. Who knew it would only take a few years. The wolves on the Slate Islands have now starved to death after eating all the caribou and there are only a few Caribou remaining on Michipicoten.

  • Bryce

    Update. Delicate dance only lasted a few years. With caribou trapped on the islands with no room to hide in space, no escape habitat, and no large open areas to use their speed to outrun the wolves it was only a matter of time. It appears they are extirpated on Slate and the wolves have starved to death and the caribou on Michipicoten have declined from around 680 to 30 animals with a wolf pack still numbering over a dozen within weeks of doing the same thing that happened on the Slate Islands. It’s now likely just a matter of time before the last of the Great Lakes Caribou are extinct.

    • KM

      I won’t be taking this picture with a wolf in the background…. Breaks my heart along with everyone who owns cabins on the island

      • Bryce

        Breaks my heart just hearing about it!!! I’m from the states (Minnesota) and my wife and I have wanted to go see the caribou for years! We were actually planning on going this summer (either Slate or Michipicoten) until we heard about the current situation. We were originally going to include Pukaskwa in our trip until last winter when I emailed park officials about their most recent survey and they informed me that it confirmed all the caribou were gone.
        I have friends who have seen them on Nipigon and even one on the Minnesota border on Lake of the Woods but nothing up close like that pic you have!

        Thank you for sharing that with me!

  • Greeley Miklashek

    So, in 2015 there were 300 Caribou on Michipicoten Island, but now only a handful of scrawny males survive and wolves are not to blame for this population crash. This picture has been repeated many times in other island mammal population studies. Clearly these animals overpopulated their food supply but, obviously, there is more to the story. Crowded mammal researches conducted over the past 80 years have identified the role of crowding stress in regulating mammal populations and holding them within the carrying capacity of their environment. I suggest that “population density stress” (my term) has been the real cause of this collapse and that crowded human populations are headed for the same fate. We already know how much sicker we are than traditional living hunter-gatherer migratory clan groups. In 1932 Dr. Percy Donnison and his medical colleagues examined 238,851 rural Kenyans and did not find a single case of heart disease. See the chart of page 10-11 of his 1937 book. Heart disease is the number one killer of us crowded “modern” urban Westerners. I’d love to know what autopsies of these dead Caribou show. I believe that rising infertility caused the Caribou population crash, along with starvation. Americans are experiencing a 100% increase in infertility: 8% in 1982, but 16.7% in 2016. We are on the same trajectory, especially in our crowded urban centers. If the current infertility rate increase is exponential, and our populations continue to increase, we could possibly see the last live human birth in those crowded populations as soon as 2,102. If you haven’t read or seen the movie, “Children of Men”, I highly recommend it. P.D. James called the day of the last birth, the “omega” point. Stress R Us

  • Greeley Miklashek

    Sorry, but I’ll stick with the National Geographic blog story of what happened on Michipicoten Island, which you apparently didn’t bother to read on the net. Your lengthy story is just that, a story. You did not explain the population crash(es). Again, this picture has been reported many times by biological researchers studying island mammal populations over many years. Many of the “just so” stories on the net also attrribute the caribous die off to wolf predation. The NG biologists autopsied the wolves and found no evidence of caribous in their diet. I’ll stick with the evidence-based science, but you should feel free to make up any story you like. And, by the way, the wolves air-lifed off the island were all males. No females survived, which is typical of the population collapse scenarios. Your arrogance is doing a great job of protecting you from new learning but I’ll stick to being a student and continue searching for new info where-ever I can find it. Oh, yeah, the natural population density of the boreal caribou in that area of Canada is a tiny fraction of the extreme crowding found at the maximum densities of these island populations. Sadly, I can”t find any autopsies of the caribou. I’d love to know the cause of death and what their adrenal glands looked like. UW-MSN was a center for animal crowding research in the late 1940’s and early 1950’s producing many fine papers by Charles Southwick and others You might want to read a couple.

    • Bryce

      Wow, if your going to play scientist the least you could do is get the pertinent FACTS correct. The animals that were airlifted a couple days ago were almost exclusively COWS. The animals remaining on the Slate Islands (not Michipicoten Island) were bulls, hence the reason only cows were needed for the reintroduction. If you would like me to site one of the hundreds of legitimate news agencies and or articles that reported on this (with pictures) feel free to ask and I will be more than happy to provide them to you.

      The rest of what I stated was all FACT. Believe it or not all of this information comes from what I’ve read from the actual biologists that work there. It is all public record and if there are any facts that you believe are just “stories” then state them specifically and I would be more than happy to share them with you.

      P. S. Wolves would not likely have Caribou remains in their feces during the summer when the abundant beaver population is readily available.

      Here’s a question. What are the wolves eating during he winter???
      There is only one answer as there was only one food source available. Evidentially the Nat Geo researchers were only there for a few days during the summer.

About the Blog

Researchers, conservationists, and others share stories, insights and ideas about Our Changing Planet, Wildlife & Wild Spaces, and The Human Journey. More than 50,000 comments have been added to 10,000 posts. Explore the list alongside to dive deeper into some of the most popular categories of the National Geographic Society’s conversation platform Voices.

Opinions are those of the blogger and/or the blogger’s organization, and not necessarily those of the National Geographic Society. Posters of blogs and comments are required to observe National Geographic’s community rules and other terms of service.

Voices director: David Braun (dbraun@ngs.org)

Social Media