In January 2018, the entire population of Lake Superior woodland caribou nearly went extinct. Once the dominant deer species across the north, woodland caribou had roamed from Hudson’s Bay to Mackinac Island in Michigan. They had persisted for more than 1.6 million years in North America, thriving through the dramatic environmental fluctuations of the Ice Age. 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.
But in 2018, the last two dozen individuals were trapped on Michipicoten Island and the Slate Islands on the Canadian side of Lake Superior with a burgeoning wolf population. Community members from Wawa Ontario, led by Leo Lepiano of the Michipicoten First Nations, retired Ministry Biologist Gord Eason, and cottager Christian Schroeder, urged the Ontario Ministry of Natural Resources and Forestry to save these last woodland caribou.
After media attention to the caribou’s plight, the Ministry acted.
As Senior Policy Advisor Katherine Olejarz explained, this took some time, because the team had to “ensure the correct permits, safety procedures and logistical plans, complete with contingency plans” were in place, and then they needed “to execute a complex translocation in a remote island setting located on Lake Superior. In this type of translocation, weather is a big factor with human and animal health being the number one consideration. Suitable ice and snow conditions were required to safely land aircraft and capture the caribou.”
In three dramatic interventions between January and March 2018, biologists captured caribou in large nets. Several were taken back to the Slates archipelago, where wolves had vanished after eating most of the caribou and others to Caribou Island 35 km (22 mi) south of Michipicoten Island.
But what lies in wait for woodland caribou in a warming world? Can last-minute interventions continue to bring them back from the brink? Does it make sense to save a few last woodland caribou, if they’re doomed to extinction in the Anthropocene anyway? To answer that question, it’s important to understand the species and this population in a larger historical and geographic context.
Woodland caribou are part of the globally-distributed species Rangifer tarandus, which includes reindeer in Eurasia, barren ground caribou across the North American Arctic, and woodland caribou in the boreal subarctic. Members of the Cervidae (deer) genus, which includes deer, elk, and moose, caribou thrive in a variety of habitats. They are a migratory species that can cover vast distances across the tundra or adapt to much shorter migrations in forests. Barren ground caribou and Eurasian reindeer are famous for migrations covering more than a thousand kilometers (621 miles), while Lake Superior woodland caribou have shorter movements from wintering to calving ranges.
Woodland caribou face grave challenges across North America, not just in the Lake Superior basin. Across Canada, they’ve retreated from 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, while all US populations were functionally extinct. As Hillary Rosner writes in The Atlantic, in Alberta, where oil and gas development overlaps with caribou ranges, those populations are “shrinking by half every eight years. Scientists now predict that nearly a third of Canada’s boreal caribou could disappear within the next 15 years.”
In the Lake Superior basin, a genetically distinct population of woodland caribou developed, ranging as far south as the Lower Peninsula of Michigan and north to Hudson’s Bay in Canada. Woodland caribou were widespread across the northern forest, but according to caribou researcher Thomas Bergerud, were never particularly abundant in any place, for low caribou numbers helped keep their wolf predator populations low. Unlike the much larger moose, which may stand their ground and kick a wolf trying to eat a calf, caribou flee from predators. They find refuges from predation in deep snow, windswept barrens, dense bogs, or rocky coastlines, where wolves falter.
Predator avoidance was a strategy that served woodland caribou well in North America for over a million years, but now they are vulnerable to predation if their migration routes are cut off by development, or if predator populations increase with human disturbance. And many forms of human activity do increase predation. Railroads, logging roads, forest conversions, and wetland drainage have offered easy access for human and canid predators. White-tailed deer have expanded their range into caribou territory, for the edge habitat left by forestry serves them well. Deer, in turn, invite higher wolf populations, while also spreading a parasitic brain worm that kills caribou but not deer.
Caribou declines in the Lake Superior Basin
The species is believed to have been extirpated from Wisconsin in the mid-19th century, with the last reported caribou taken by a hunter in the state in 1850. By 1912, caribou were gone from mainland Michigan. In Minnesota the vast muskeg wetland complex near Red Lake gave wintering caribou a place to hide from hunters and wolves. But by the early 1920s, Minnesota caribou were endangered as well. Homesteaders had drained much of the Big Bog, hoping to turn the peat wetlands into a rich farmland. During the Great Depression, homesteaders abandoned their failed farmlands in the Big Bog area, and wildlife managers experimented with converting them back to wetlands and restoring caribou to the bogs. Managers blocked drainage ditches to flood abandoned fields, and they scraped out wallows in the peat to create caribou habitat. A 324,000-acre area of the Big Bog was protected as the Red Lake Wildlife Refuge complex.
Nevertheless, despite all their efforts, in 1937 only three cows were left of the Big Bog herd. Biologists from the federal Soil Conservation Service stepped in to help the state, translocating caribou from Saskatchewan to the Minnesota herd. They penned the animals inside protective fences, hoping to build a larger herd by sheltering them from predators. But inside the pen, the woodland caribou failed to thrive. Some were released and headed for their traditional calving grounds up in Canada. But development along the Rainy River blocked their traditional migration route, and without a way to reach their calving grounds, the isolated population failed to sustain itself.
Into the 1980s, scattered reports of woodland caribou in the Boundary Waters and the Superior National Forest of Minnesota raised hopes that a few Lake Superior woodland caribou still survived in the United States. Two individuals straggled down Minnesota’s rocky coastline near the Canadian border during the winter of 1980-1981. One may have been hit by a car and the fate of the other is unknown. Discussions of restoring woodland caribou to the Boundary Waters Wilderness Area petered out when white-tailed deer became established in northeastern Minnesota. In the United States, woodland caribou are now a ghost species persisting only in place names and memories.
On the Canadian side of Lake Superior, the population of woodland caribou have fared better, yet they too have “been driven off the land,” according to Leo Lepiano, Lands and Resources Consultation Coordinator for the Michipicoten First Nations. By 1912, the Lake Superior woodland caribou had been hunted out from the western shore and Thunder Bay region. In the Lake Nipigon watershed just north of Lake Superior, caribou thrived until the Canadian National Railway came through in 1910, and then that population dwindled (although islands in Nipigon Lake do support some breeding woodland caribou to this day).
Along the north central and northeastern shores of Lake Superior, well into the mid-20th century, woodland caribou range remained continuous all the way north to Hudson’s Bay. But after World War II, mineral, forest, and energy development fragmented their range, and caribou populations became discontinuous, with the Lake Superior population cut off from the more northern populations. This wasn’t a northwards migration, with caribou expanding into new territory. Rather, according to retired Ministry wildlife biologist Gord Eason, it was a cascade of local extinctions driven by hunting, predation, and habitat loss.
Late into the 20th century, Lake Superior woodland caribou persisted along the coast in Pukusawa National Park and on islands that were free from wolves—particularly the Slate Islands 12 km (7.5 mi) off the coast near Terrace Bay Ontario. When wolves were absent, woodland caribou populations were able to increase exponentially, even to the point of denuding their island habitat. In the early 1980s, Eason translocated 9 caribou from the overpopulated Slate Islands to then wolf-free Michipicoten Island. At 184 square km (114 square mi), Michipicoten Island was large enough to support a substantial caribou herd. By 2012, the population on Michipicoten had grown exponentially, from 10 to perhaps 1000 individuals. On the Slate Islands, caribou populations may have increased to more than 640 individuals, according to Eason.
But in the cold winter of 2013-2014, wolves crossed ice bridges to both island refugia. Within two years, only a few lone male caribou were left on the Slates, and on Michipicoten Island, a healthy population approaching 1000 individuals crashed to a few dozen. While woodland caribou can handle wolf predation if wolves were at very low densities, the wolf population on Michipicoten had skyrocketed and, the caribou were unable to escape their predators.
Soon after wolves appeared on the islands, the informal coalition of the Michipicoten First Nations Community, local cottagers on Michipicoten Island, and caribou biologists urged the Ministry to protect the Lake Superior caribou from extinction. Options discussed included culling the island wolves (unpopular with wolf advocates) or moving wolves to Isle Royale in Michigan, where the US National Park service had for years been considering a wolf restoration effort. Alternatively, if wolf control was impossible, then caribou could once again be translocated to wolf-free islands.
From locals’ perspectives, the Ministry seemed slow to act. The later decision to translocate animals to the Slates archipelago and Caribou Islands has met with the general approval of the informal community coalition. But group members remain engaged and are looking to the future.
In a 2018 interview, Lepiano and Schroeder shared their concerns regarding the continuing political and environmental forces affecting the caribou. Lepiano noted that if the caribou vanish, many management dilemmas faced by industry and the ministry might vanish as well. “There’s a tremendous political pressure from certain interest groups to not have to deal with the caribou on the mainland,” Lepiano said. Currently, development in Canadian woodland caribou range cannot exceed 35% of the landscape, as outlined in the 2012 federal Boreal Caribou Recovery Strategy.
That limit would be lifted for the so-called “discontinuous range” between Lake Superior and the northern populations if Lake Superior caribou went extinct. More of the boreal forest could be opened to transmission line development for new hydropower projects, intensive forestry, and Ring of Fire mining expansion. Wawa resident Christian Schroeder, an advocate for translocation, explained: “The transmission line that they’re running through here is intended to run power to the mining infrastructure in the Ring of Fire, which ironically I will remind you, is prime caribou habitat in northwestern Ontario. And caribou are a real pain in the butt.”
Schroeder suggested that many biologists and policymakers within the Ministry share a perception with environmental NGOs that climate change will inevitably doom the caribou. “Caribou in Canada may be doomed by climate change and habitat loss” proclaimed one headline in Nature World News on Dec. 16, 2013. A 2017 scientific paper in Rangifer by Sara Masood and colleagues projected “complete loss of woodland caribou in Ontario if winter temperatures increase by more than 5.6º C by 2070. The attitude may be, climate change is going to eliminate woodland caribou anyway, why expend resources to save them, when those resources could be used on other, less vulnerable species?
Caribou and Climate Change
But are woodland caribou really doomed by climate change—or has climate change become an excuse to avoid the difficult political choices that might restore woodland caribou? Given half a chance, caribou may be far less vulnerable to climate change than many other northern species.
Physiologically, unlike moose that cannot forage well as temperatures warm, woodland caribou don’t experience thermal stress—at least not in the range of temperatures predicted for Lake Superior. Moose begin to experience thermal stress at 14ºC, panting and foraging less. Caribou, however, don’t show measurable physiological responses until temperatures reach 35ºC.
Popular perception holds that wintering woodland caribou require old growth boreal forest with abundant lichens—and those forest types probably won’t survive along much of Lake Superior as the climate warms. Does that mean caribou cannot survive either? Not at all. While caribou select lichens in winter if they’re available, they readily adapt to other habitats, according to a 2007 study by Bergerud and colleagues. Michipicoten Island, for example, has a mixed forest dominated by hardwoods, and caribou thrive there in the absence of wolves.
Caribou responses to historical climate change offer clues to how caribou might respond now. One of the few large megafauna species to expand rather than go extinct in the Late Pleistocene, caribou survived repeated glaciations by moving to ice-free refugia. Boreal woodland caribou found refuge in the Appalachian Mountains, while Eurasian reindeer moved to what’s now Italy, France, and Spain.
At the end of the last glacial maximum, the fossil record shows that caribou did vanish from their warming refugia. Anthropologists Don Grayson and Francoise Delpech interpret this climate history as evidence of the profound vulnerability of caribou to future climate change. But this interpretation reduces the agency of caribou themselves. Post-glacial caribou didn’t simply go extinct (as they later did in the 20th century Lake Superior range reductions). Rather, caribou chased the melting ice north, exploring new environments that were opening up as the climate warmed and expanding their range across the circumpolar north. North American caribou populations actually expanded in size at the end of the Pleistocene, as other Pleistocene megafauna (with the exception of brown bear and tundra muskox) went extinct. Migration was central to caribou post-Pleistocene resiliency, suggesting that they can be resilient if their habitats are connected. Each time the ice retreated in an interglacial period, caribou followed the melting ice north, expanding into new habitats across a diverse, warming landscape.
People and Caribou
Across the north, a striking diversity of human-caribou relationships developed—and we may need to learn from those historic relationships to help woodland caribou survive the Anthropocene. In Siberia and Mongolia, Indigenous peoples fully domesticated reindeer, creating close spiritual and material relationships with them. In Sápmi (northern Finland, Sweden, and Norway), the Sami people continued to hunt rather than domesticate reindeer well into the 16th century AD. But when Europeans colonized Sápmi for mineral, forest, and agricultural resources, wild reindeer populations declined as the Sami and Europeans began hunting them past their ability to reproduce. The Sami developed a semi-domesticated relationship with reindeer to protect their remaining populations, shepherding them on their long migrations but never fully taming them as beasts of burden.
In contrast, North American caribou remain wild, and Indigenous peoples have not domesticated or tamed them. Yet the two species, humans and caribou, have developed extraordinarily close material and spiritual relationships across North America. For example, Gwich’in leader Sarah James said, “The Gwich’in are caribou people” who believe that “a bit of human heart is in every caribou, and that a bit of caribou is in every person.” According to anthropologist Piers Vitebsky, caribou have made human life across the Arctic possible as climates changed in the Late Pleistocene, allowing people to thrive in ecosystems that would otherwise have been uninhabitable.
What can we learn from caribou histories to help us forge resilient relationships for the future? One lesson is that people and caribou have long had intertwined histories, and caribou may now require continuing care, a need to keep investing time, resources, and energy to manage their predators and migration routes. Caribou will indeed dwindle in a warming world if we do little to protect them.
What’s next for the Lake Superior woodland caribou? The Ministry has solicited advice from the public on the development of a revised management approach for the Lake Superior population, and staff plan to hold Indigenous community and stakeholder consultations in 2019. Possibilities range from doing nothing, to maintaining caribou on the off-shore islands, and even trying to restore connectivity to the northern populations.
For now, a fragmented population persists, thanks in large part to the efforts of the Michipicotan First Nations community and other concerned biologists and citizens. Climate change should not be an excuse to give up on the management strategies here and now that could keep them from extinction. Climate change isn’t going to doom woodland caribou. Human policy decisions, however, might.
Nancy Langston is Distinguished Professor of Environmental History at Michigan Technological University. Her most recent book is Sustaining Lake Superior: An Extraordinary Lake in a Changing World (Yale 2017). She is currently working on an environmental history of woodland caribou and common loons in the Anthropocene. This essay is modified from a piece that appeared in HistoricalClimatology.com in July 2018, https://www.historicalclimatology.com/blog/are-woodland-caribou-doomed-by-climate-change, used with permission.