DULUTH, Minn. —The caribou of the Lake Superior region, which once numbered in the thousands across a wide swath of three states and Ontario, are surviving on just two islands and a small herd on the mainland as their future continues to be uncertain.
After a dramatic airlift operation in 2018, an estimated 23 caribou seem to be doing well on Ontario’s Slate Islands on Lake Superior, with maybe 10 on Caribou Island on the big lake. About 20 survive on the North Shore mainland east of Marathon, Ont.
And that’s it. About 50 animals in three small groups.
“We’ve got enough, we think, to be genetically viable. They seem to be in a slow growth pattern now on the islands, without wolves. But we don’t know what will happen in the long-term,’’ said Gord Eason, a retired Ontario Ministry of Natural Resources and Forestry wildlife biologist who has adopted the caribou’s survival as his mission.
Isolated from northern Canada's woodland caribou herds, and possibly a genetically unique subspecies, the Lake Superior caribou have been pawns in an unprecedented wildlife chess game in recent years as supporters like Eason try to keep them one move ahead of extinction.
The animals face a vastly changed landscape due to logging and development that diminished the old growth forests that provide the lichens they eat. They also may be feeling the effects of climate change as ice patterns on the lake continue to change, mostly toward fewer years with major ice.
But most immediately the caribou have faced a relentless onslaught from wolves.
Moving the pieces around
In late 2017, we first highlighted the plight of the caribou on Lake Superior's Slate Islands and Michipicoten Island where, after growing into the hundreds in recent decades, caribou were decimated after wolves crossed ice to the islands in the Polar Vortex winter of 2014. That was the first ice bridge in years. The wolves stayed, reproduced and feasted on caribou that had no way off the island and, over decades with no predators, apparently lost their survival and escape instincts.
On the Slate Islands, the wolves cut caribou numbers from an estimated 650 to just 2, both mature bulls, before the wolves themselves died off from starvation. On Michipicoten, wolves took just four years to cut caribou numbers from as many as 1,000 to fewer than two dozen. While woodland caribou can generally avoid wolves when both are at low densities — spread out in vast forests — wolf numbers on the islands grew to unusually high densities, and caribou couldn’t avoid the predators. The Slates are about 14 square miles total. Michipicoten is about 70 square miles. Both are about 9 miles off the mainland. They went from having the highest woodland caribou densities in the world to the highest wolf densities in the world, Eason noted, in a biological blink of an eye.
“We really thought that was it. The ministry (Ontario Ministry of Natural Resources and Forestry) waited so long to do anything we thought it was going to be too late,’’ said Leo Lepiano, a natural resources consultant for the Michipicoten First Nations.
In early 2018, as time seemed to be running out — thanks to a batch of media attention and constant pressure from caribou supporters, including the Michipicoten First Nations tribe — Ontario officials agreed to trap and air-lift the last 15 caribou off Michipicoten Island. Nine went to the Slate Islands where wolves had either left, or starved, after eating themselves out of caribou. Six of the Michipicoten caribou went to Caribou Island, which also was free of wolves because it is so far from the mainland. (Ironically, the Michipicoten caribou were descendants of Slate Island caribou that had to be air-lifted to Michipicoten when the Slate population became overpopulated.)
Analysis of trail camera photos, radio-collared cow caribou, tracks and some sightings confirmed the Slate Island herd is breeding and reproducing. Eason said 15 caribou were confirmed in 2019 and as many as 23 caribou may live there now from the nine that were transplanted and two legacy bulls that had survived on the island on their own. On Caribou Island, calf tracks have been spotted, and Eason estimates as many as 10 caribou may be there now from the six that were released in 2018.
More calves should come this spring.
“We really don’t know how many. We hope to go out and get the cards off trail camera very soon, when conditions on Lake Superior allow it, and get a better sense of how many calves there are,’’ Eason said, noting that it’s also especially important to confirm that at least two bulls survive on each island to keep the genetic makeup of the herd strong.
The islands are bastions of safety for the caribou, when there are no wolves. There is plenty of food, little or no disease, no predators and no human-caused mortality like vehicles, trains or poaching.
Continuing the chess game, most of the remaining wolves on Michipicoten Island were trapped and transported to Isle Royale on the U.S. side of the lake in early 2019. They likely faced starvation, with no caribou remaining on Michipicoten, and the U.S. National Park Service wanted the wolves to bolster Isle Royale’s decimated population.
Now, surprising the wildlife experts, two wolves have survived on Michipicoten Island, even with no caribou, apparently eating beaver and snowshoe hares. And Eason and others are eyeing the island for the next chess maneuver; another caribou return. No new wolves have been able to get to Michipicoten for the past five winters as ice bridges become less frequent in a warming climate.
“That’s the goal, when and if those last two wolves are gone, to get caribou reestablished on Michipicoten. The (Michipicoten First Nations) really is taking the lead on that,’’ Eason said.
Mainland herd critical
It’s hoped, starting in 2022, a few caribou can be taken from the Slate Islands each year over several years to repopulate Michipicoten Island yet again. But Eason said that, to truly save the genetic characteristic of the Lake Superior caribou, more has to be done to bolster the mainland herd on the North Shore. That means using the island’s eventual excess caribou as feeder stock to bring new caribou to the mainland where mortality rates have been higher than reproduction.
“We think they’re in their last stages’’ on the mainland, Eason said. Without an infusion of new animals, the mainland caribou herd, declining by about 4% each year, may be gone in a matter of years.
“If we want to keep Lake Superior caribou in a more sustainable fashion, we have to have them survive on the mainland,’’ Eason says. “That’s where they have done the best job at developing the survival instincts to make it on their own. That’s really the long-term goal here.”
Eason said suitable habitat remains from Rossport, Ont., in the west to Pukaskwa National Park in the east. Farther east or west and the caribou would run into more human development, younger, frequently-logged forests and more deer. Deer carry a parasitic brainworm that is fatal to caribou. Caribou almost certainly could not survive on Minnesota's portion of the North Shore because of high deer densities.
What’s next for the last Lake Superior woodland caribou? Provincial officials asked for public comments on a new management plan for the Lake Superior caribou population in 2018 and the agency met with tribal officials and other stakeholders last year. So far there is no formal plan announced. Possibilities range from doing nothing, to maintaining caribou only on islands, to bolstering the mainland herd and even trying to restore habitat connectivity to the nearest northern caribou populations nearly 100 miles away near Lake Nipigon.
“The provincial government is currently considering all input received as well as the best available science and social and economic information’’ to develop a management plan, said Hilary Gignac of the Species at Risk Branch of the Ontario Ministry of the Environment, Conservation and Parks. "At this time a preferred management approach has not been determined and we continue to welcome all feedback and perspectives.”
Meanwhile Parks Canada officials are looking at restoring caribou to Pukaskwa National Park.
Christian Schroeder, who owns a cottage on Michipicoten Island and watched as wolves began to decimate caribou numbers there, said he became involved when it became clear no government agency was taking any action. He’s noted that human activities, and lack thereof, in the past lead to the caribou’s demise and that humans have to find a solution.
“It was clear to me that there was no plan whatsoever … but to let nature take its course, whatever that means,'' Schroeder said, adding that it appeared government officials were willing "to let the caribou disappear from the Superior watershed. I couldn't let that happen, considering how precious every single caribou population is.”
Lepiano said a joint effort between provincial, federal and tribal governments going forward could succeed at saving the Lake Superior caribou, and maybe succeed at restoring trust between the parties.
“My dream is that the (successful restoration of) Lake Superior caribou will become a cornerstone for a new collective form of resource management and cooperation around Lake Superior,’’ he said, noting the caribou are not just culturally significant but could become an eco-tourism economic boon for the local economy.
But even Eason wonders how long the chess game with wolves and caribou can go on; whether it’s sustainable to keep moving animals around in the effort to save a species that already is at the southern edge of its changed habitat in a warming world.
As of now, though, he’s not willing to stop trying.
“In the short term, this is the price we pay for having failed to do our job and protect them and their habitat in the past,’’ Eason said. “I don’t know if this will work. But I’m not giving up.”
For more information go to @SuperiorCaribou on Twitter.
Did you know?
Lake Superior woodland caribou are part of the species Rangifer tarandus, which includes reindeer in Eurasia, barren ground caribou across the North American Arctic and woodland caribou in the boreal forests of Canada.
Once the dominant deer species across the north, woodland caribou roamed from Hudson’s Bay to Mackinac Island in Michigan. They persisted for more than 1.5 million years in North America. When glaciers encroached, they found refuge in the southern mountains of Appalachia; when temperatures warmed, they moved northward with the melting ice to fill the forests and islands along Lake Superior. They managed to thrive despite predators and hunting by indigenous peoples. But they couldn’t survive European settlement that brought over-hunting and development — namely farming, mining and logging.
The last caribou seen in Michigan was in 1912. The last one in Wisconsin was in the 1850s. And while most had been wiped out in Minnesota by the 1920s, one last caribou was still hanging around Angle Inlet of Lake of the Woods in 1937. (There were some isolated reports of caribou near Grand Portage 30 years ago, but none recently.)
Across Canada, caribou have abandoned roughly half their 19th century range. By 2017, across Canada, more than half of the 57 distinct populations of woodland caribou were in steady decline, with all U.S. populations functionally extinct (a few animals may migrate into Idaho from Canada on occasion.)
Sources: Encyclopedia of Life; canadiangeographic.ca; National Wildlife Federation; U.S. Fish & Wildlife Service.