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National Wildlife Week was April 10 to April 16 this year. The purpose of the annual week is to draw attention to wildlife conservation issues.
This article is about the conservation and restoration of the Lake Superior caribou. These caribou are one of several isolated pockets of woodland caribou along the southern edge of their range in Canada that are in immediate danger of being lost.
Woodland caribou spent the last glaciation in the Appalachian Mountains of the eastern United States. As the ice receded, the caribou spread through the forest all along the south edge of the ice. Caribou returned to the Lake Superior area about the same time people arrived. So for about the next 10,000 years caribou provided for and co-existed with the people in this area.
Things began to change about 200 years ago with European settlement. More caribou were shot to feed an increasing population. Caribou habitat was also lost to agriculture, settlements, railroads, roads, pipelines, electrical transmission corridors and mines.
The largest habitat loss was from logging, which focused on old conifer forests, often with tree and ground lichens that are the classic winter food of caribou. These old conifer forests were replaced by young forests with a higher component of deciduous shrubs favoured by moose. The increase in moose in these regenerating forests resulted in an increase in wolves.
The smaller and sparser caribou were simply unable to withstand this increase in predation, and they steadily declined. By 1980, caribou were gone from the southern, western and eastern shores of Lake Superior and almost all the offshore islands.
There were only scattered caribou on the mainland along the northeast part of the lake, and they were isolated from the main caribou range to the north. Of the islands in Lake Superior, which all had caribou at one time, they remained only on the Slate Islands south of Terrace Bay.
In the early 1900s, six caribou were moved from Newfoundland to Caribou Island to restore the population there. In the 1980s, caribou from the Slate Islands were moved to Michipicoten Island and to the offshore islands and mainland of Lake Superior Provincial Park on the east side of the lake. These populations persisted from 10 to about 40 years. They could have persisted longer, but additional efforts were not made to supplement them or protect them.
In the winter of 2014, wolves found their way on the ice to both the Slate Islands and Michipicoten Island. By 2017, they had eliminated almost all the caribou from the Slate islands.
Only two adult males were thought to have survived. This is called “functional extirpation” because the population cannot rebuild from one sex. In 2018, the wolves completely extirpated the caribou from Michipicoten Island.
However, a few caribou were rescued at the last minute. By 2014, there were only a very few caribou left on the north shore of Lake Superior. In total, there were probably about 1,100 Lake Superior caribou in 2014 – mostly on Michipicoten Island.
By 2018, there were probably less than 30 in the entire Lake Superior area. This catastrophic decline is one of the characteristics of island biogeography. Relatively small islands like the Slates and Michipicoten are simply not large enough for caribou to space out and evade predation by wolves.
In the winter of 2018, nine caribou (eight adult females and one adult male) were moved from Michipicoten Island back to the Slate Islands. They joined the two remaining adult males there with the hope of restoring that population.
Just after that, six caribou (four adult females and two adult males) were moved from Michipicoten Island to Caribou Island. They were among the last of the caribou on Michipicoten Island and were intended to form a secure backup population of the Lake Superior caribou that could not be reached by wolves.
These are very small founding populations, especially the male component, so inbreeding problems are a worry. However, these last caribou from Michipicoten are also the survivors of an extreme predation event and are therefore likely very fit – both physically and genetically.
In terms of numbers, there are now likely around 35 caribou on the Slate Islands and about 20 on Caribou Island. The last few aerial surveys of the north shore of Lake Superior have not turned up any caribou.
So, after persisting for 10,000 years, they are now likely gone from the mainland along Lake Superior. Although the caribou populations are growing in the two restored island locations, they are not out of danger. The Slate Islands are very susceptible to re-invasion by wolves when ice bridges form to the mainland. Caribou Island is small and very susceptible to over-population and subsequent starvation.
Plans are in the works to restore caribou to Michipicoten Island. The island just needs to be free of wolves before caribou can be moved back
Biigtigong and Michipicoten First Nations are also interested in restoring caribou to the mainland along Lake Superior in their traditional areas. This would include Pukaskwa National Park and the Conservation Reserve between Pukaskwa and Wawa.
Prospects for these mainland restorations are good. Ecosystem conditions are thought to be better now than when the caribou disappeared from these areas. Pukaskwa National Park has stopped their prescribed burning program in a zone 10 kilometres back from the shore, so habitat should be getting better for caribou rather than moose.
Aerial surveys in the park also show moose numbers at a level where caribou should be able to co-exist with predator numbers. However, periodic supplementations of the caribou may be necessary until ecosystem conditions return to being completely self-sustaining for caribou.
Getting caribou back to Michipicoten Island and restoring a viable caribou population on the mainland will greatly increase the security of the Lake Superior caribou. This will reverse the continent-wide trend of caribou population decline and range recession in at least this small part of Ontario.
It will also begin restoring a species that helped the Indigenous people survive here for thousands of years and that they wish to return the favour to.
If you want to help these animals, there is something you can do. You can write Minister David Puccini of the Ontario Ministry of Environment, Conservation and Parks at [email protected] and ask him to help restore the Lake Superior caribou to Michipicoten Island and their recent range on the mainland.
The Lake Superior Cabribou Group is a collection of scientists, biologists, conservationists and naturalists committed to restoring Ontario Lake Superior caribou population. This submission was written by Gordon Eason (Wawa), Brian McLaren, Ph.D. (Thunder Bay), Christian Schroeder, Ph.D. (Quebec Harbour), Serge Couturier, Ph.D. (Lévis) and Steven Murphy (Wawa).
