Pieces of the Puzzle part II: biologists acting to improve ecological balance


A gray wolf at Isle Royale.

Story and photo by Scot Stewart

“A wolf singing of the beauty of the night, singing as no human voice had ever done, calling on a mate to share the beauty of it.”

The wonder, surprise and intrigue of the Isle Royale wolf story has continued this winter as scientists from the National Park Service and Michigan Technological University moved forward with their plans. The center of the world’s longest running mammal study has been in the spotlight as these scientists have attempted to bring a biological balance, featuring the wolf, back to this Lake Superior wilderness.
When wolves crossed the ice from Ontario to Isle Royale during the winter of 1948-1949 it sent shockwaves through the 44-mile-long island full of moose. It created a closed ecosystem of wolves, moose, boreal forest, tapeworms, beaver, snowshoe hare and U.P. weather.
The wildlife species of Lake Superior have become pieces in an elaborate biological chess game. Moose first appeared on Isle Royale in the early 1900s. Their population became established quickly on the island though some doubt on how they arrived.  Moose have been observed swimming across the 14-mile stretch of Lake Superior between Canada and Isle Royale. There is some evidence to suggest moose were introduced to the island by a group of individuals not associated with MiDNR or other government organizations according to a page on the park’s website. Twelve white-tailed deer were introduced on the island in 1906, but they all quickly died.  Red foxes were also introduced on Isle Royale around 1925.
Since first moving onto Isle Royale on their own during the winter of 1948-49, wolves have made several crossings since.  A single male crossed to the island in 1997, giving the biological diversity a boost. In 2008 an ice bridge formed, and it is believed two radio-collared wolves may have left the island. On at least one occasion a wolf walked across the ice to the island but turned around and returned to the mainland.
The population of wolves on Isle Royale dropped to a historic low of two last year, a male and his daughter. After a great deal of consideration and discussion, the National Park Service decided to proceed with a plan to trap wolves from a number of locations around Lake Superior and move them to Isle Royale to increase the size of the population to a level where it could have a more significant impact on an increasing moose population. Without a natural way to keep the ungulate numbers in check, their browsing would in turn devastate the balsam fir on the island and drastically change the composition of the forest there.
The concept of bringing new wolves to the national park, with its 60-year-old mammal study, was met with some concerns. Some believed nature should run its course and allow biologists and others the opportunity to see what would happen. Would more wolves walk to the island on their own? Several ice bridges to Isle Royale have formed in recent years, including this year, and wolves could return without human help. The two remaining wolves are not breeding and their impact on the island’s moose are negligible.
The National Park Service, with the encouragement of biologists from Michigan Technological University conducting the long term moose-wolf study, decided to bring new wolves to the park.  Last fall 16 wolves were live trapped on the Grand Portage Chippewa reservation near the Pigeon River on the Minnesota-Ontario border. Four were selected for their size, health, age – between two and five and sex – three females and a male, and were taken to Isle Royale for release. A pair was released on the island Sept. 26, and single females were released on Oct. 2 and 4.
For even the small group of wolves, there were plenty of interesting opportunities to learn more about this plan. Wearing radio collars, the relocated wolves provided a mapping of their travels as they explored the entire island. Biologists noted the new arrivals avoided the territory occupied by the original pair. Then on Nov. 13, Isle Royale National Park announced the male released on the island had died.  Its remains were recovered and sent to the University of Wisconsin. The cause of death has not been released but no obvious signs were immediately apparent.
Another surprise came in early February as a temporary ice bridge afforded an opportunity for one of the relocated females to leave the island and return to the Canadian mainland. Its departure was noted at the conclusion of the month-long government shutdown. The annual seven-week winter study of wolves and moose on the island was delayed by shut down, so when biologists arrived they followed the tracking signal on the ice toward the mainland. Satellite tracking indicated the wolf’s path was not a straight line, but a walk northeast before making a nearly 90 degree left hand turn back to a small island on the Canadian shore before arriving on the mainland a few miles north of the U.S.- Canada border.
Studies have shown captured wolves released less than 80 miles from their home range will make an attempt to return home. The new Isle Royale wolves were held a short time on the island before release to help them acclimate to their new home, but the main bet was they would be unable to cross an ice bridge due to their rarity. This winter proved to be one of those unusual ones with a large amount of ice on Lake Superior and several opportunities for wolves to move in either direction.
Severe winter conditions delayed the next step in the plan to increase the number of wolves on Isle Royale. This step came from a giant part of the Lake Superior chess game. Canada agreed to provide wolves trapped on Michipicoten Island (71.4 mi2 – 184 km2), the third largest island in Lake Superior. Only Isle Royale (206.7 mi2 – 540 km2) and St. Ignace Island in Ontario (105.8 mi2 – 274 km2) are larger.

A female moose and calf are seen feeding in the snow on Isle Royale.

This part of the story though has threads rooted in pre-settlement times around the lake. Moose were not the primary member of the deer family in the region before the arrival of Europeans. In the very earliest of times, after the retreat of the last glacier, caribou began to appear. They may have been in parts of Lower Michigan as early as 13,000 years ago, and fossil remains of what may have been a caribou have been found at a site of Paleo-Indians in Macomb County dating back to 11,200 years ago, reported by C. E. Cleland in American Antiquity in 1965. They disappeared from the Lower Peninsula around 1853, seen occasionally on Beaver Island in Lake Michigan. Caribou left the U.P. around 1912 or 1914, and departed from Isle Royale in 1925. It should be noted two of these final refuges are islands.
As the Lake Superior region was logged, mined and developed, the boreal forest habitat of the woodland caribou shrank quickly, and as it did white-tailed deer moved in from the south where boreal habitat nearly totally disappeared. The white-tailed deer brought the brain worm, a parasite, with them too. Although it does not affect deer, it is fatal to caribou and moose alike. Moose wandered down from the north where wolves discovered the remaining caribou were a lot easier to catch than the much larger moose. Caribou have managed a periled existence on the north shore of Lake Superior. Through the 1970s they continued at three sites: Pukaskwa National Park, Pic Island near Marathon, Ontario, and the Slate Islands, eight miles off shore from the town of Terrace Bay, nearly right across the lake from Marquette.
Pic Island is near the shore and within easy reach each winter for wolves. The Pukaskwa is a truly remote, wilderness national park, nearly all of its (725 mi2 – 1,878 km2) is boreal forest. Despite its rugged terrain, most of the caribou lived along the Lake Superior shore or on small islands off shore, as far from the wolves as they could get. The Slate Islands have been the classic last stand for the caribou of Lake Superior. Their population has fluctuated between low double digits to over 400 individuals on the complex of small islands with an area of 25.4 mi2 – 65.4 km2. The Slates, believed to be formed as the result of a meteorite impact, are located six miles off shore. Throughout most of the 100+ years the caribou have been known to live on the island, the site was wolf free, creating one of the most unique herds of caribou in the world. In the 1970s they were the smallest bodied, with few much over 160 lbs – 73 kg, smallest antlered, with nearly all females antlerless (female caribou typically have antlers) and with 50 percent of stags without antlers, a 10.4 percent reproductive rate, lowest of all caribou, and one of the highest population densities per square mile. Their population was regulated most by winter food availability, with large die-offs in quiet, windless, high snowfall years when tree lichen were scarce because of few blowdowns limited opportunities to reach ground lichens.
Here is where the woodland caribou, moose and gray wolf roads all intersect today. As woodland caribou populations continued to decline across the north shore of Lake Superior a decision was made to move caribou from the Slate Islands during a boom year to another wolf-free island provincial park – Michipicoten Island where a single bull was spotted in 1981. The following year a bull and seven females were air lifted to Michipicoten to create a new herd. The caribou flourished at this new home going to an estimated 450 – 900+ in 2014, living side-by-side with healthy populations of snowshoe hare and beaver.
Then came the winter of 2014-2015. Residents of the Lake Superior region will remember it as one of the coldest on record, when the entire lake virtually froze over. A new piece moved in the chess game as wolves made it across the ice to Michipicoten Island from the mainland. In just a little over two years the caribou population dropped to an estimated 30 individuals and Canadian citizens clamored for them to be saved.
The next chess pieces, caribou, were then moved. In the past, the Lake Superior ice formed bridges between the islands and the mainland and woodland caribou and gray wolves moved regularly back and forth. Now, victims of climate change, caribou locked on the island for years at a time and unable to detect lethal wolf numbers in time to leave, meet their doom.
Nine females and one bull were captured on Michipicoten and taken back to the Slate Islands. Wolves also wandered across the ice in 2014 to the Slates and all but wiped out the caribou herd. By 2017 one report stated only a small handful of bulls remained from a herd of 100 or more. It should be noted population estimates are often extremely difficult at forested sites like Isle Royale, Michipicoten Island and the Slate Islands where even large mammals can be difficult to find in dense forests.
Ontario Ministry of Natural Resources and Forest (OMNRF) biologists studied trail cams on the Slates and concluded that because of warmer winters no new ice bridges formed to assist the departure of the wolves after the caribou population plummeted and the wolves died. This created a safe home for the returning new caribou from Michipicoten.
Fearing for the rest of the caribou back there, four more females and another large bull were removed from Michipicoten and taken to yet another site, Caribou Island, 25 miles south Michipicoten, where there has been no history of wolves.
With the caribou essentially removed from Michipicoten Island, the future of the wolves was now in doubt. Questions arose about the ability of the snowshoe hare and beaver populations’ ability to feed the wolves and raised concern of the possibility the wolves would starve to death. Time for another chess move – take the wolves and move them to Isle Royale! Over a two-day period Feb. 28-March1 this year, three males, all around 90 pounds, and a 62-lbs female were trapped and taken to Isle Royale. There, they joined the two females from Minnesota, and the male and female already there. The current park plan calls for 20-30 wolves to be relocated to the island over a three-to-five-year period. Much will depend on the ability of the relocated wolves to remain, survive, form packs and reproduce in the coming years.
For many years a population of around 20 wolves lived on Isle Royale with a herd of about 1,000 moose. It seemed like there was a good balance of nature as both populations remained fairly stable. Climate change, the introduction of parvo-virus to the island, which killed many of the wolves, and inbreeding of the wolves changed that balance. Many felt the island should be left alone so nature could run its own course and humans should not interfere. Biologists feared the island’s forest would be so severely damaged it would take decades to regenerate itself.
In looking at the history of the Lake Superior region, and the current impact of humans on the land, waters, air and climate, it is impossible to separate people from the workings of the environment. It is not possible to “let nature run its course” untouched. Reintroducing wolves to Yellowstone National Park was hailed as a huge achievement in restoring the ecosystem to something close to its original state. Not only has a truer balance developed between herbivores and the flora of the park, but noticeable changes have come to that flora enhancing the habitats for many other species. Aspens have erupted along the river valleys, reducing erosion along riverbanks as elk were forced out of valleys where they are easy prey. The subsequent changes help birds, bears and other species of animals to thrive in those same valleys.
Maintaining similar balances in the islands of Lake Superior will help maintain those same kinds of balances and keep the genetic diversity of many of the species that live there higher, species healthier as the chess games and the beauty of the night continue.

Next time: how does biological diversity affect wilderness and the human spirit?

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