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The two surviving wolves on Isle Royale—pictured here in February—are to be joined this fall by wolves from Michigan and Minnesota.

Rolf O. Peterson/Michigan Technological University

Inbred Isle Royale wolves to get company, rebooting the world’s longest running predator-prey experiment

In the next 6 weeks, the U.S. National Park Service (NPS) will airlift six wolves from the U.S. mainland to nearby Isle Royale in Michigan to help restore the predator-prey system on the island, park superintendent Phyllis Green announced in a press conference today in Houghton, Michigan. The operation is to be completed by 31 October.

The airlift will drastically change the classic study of the island’s predator-prey dynamics, found in every ecology textbook.

Just two inbred wolves remain of the Isle Royale population that has been preying on moose and studied for nearly 60 years. The new wolves are to be the first wave of several over the next 3 years, expected to result in a new population of 20 to 30 wolves. With this reboot of the predator-prey system, NPS is also seeking to engage more scientists to study the unique wilderness park. “How do we restart the science?” Green asks. “We know there are many aspects of the island we haven’t researched fully.”

The original Isle Royale population was founded by two or three wolves, with occasional influxes of new genes from mainland wolves wandering over the ice in cold winters. With ice bridges diminishing, planners have considered genetic diversity of the wolves along with an equal ratio of males to females. The mainland wolves will also be collared and screened for diseases. Two wolves are to come from the Upper Peninsula in Michigan and two to four from the northeastern Minnesota reservation of the Grand Portage Band of Lake Superior Chippewa, which has likely been the home of wolves that found their way to Isle Royale in past decades. Other wolves are expected to be brought in from Canada’s Ontario province in 2019.   

Whereas Ontario wolves have experience killing moose, Michigan wolves may have never seen a moose, and Minnesota wolves may have limited experience killing them, Rolf Peterson of Michigan Technological University in Houghton told Science. So the imported wolves are going to have to learn how to bring down the 450-kilogram mammals. “However, wolves are wonderful observational learners, and hunger is a strong motivation to test any potential prey,” Peterson says. The newcomers will also find an abundance of familiar beaver, which have been booming in number along with moose as the Isle Royale wolves diminished.

This past winter, the 9-year-old male wolf on the island “was looking grizzled around the face and gray,” Peterson says. There was little sign of courtship between him and the 7-year-old female, who is both his daughter and half-sibling. The female at times pawed at the male, but “it seemed like she was [providing] elder care in a way,” says Peterson, who has studied wolves on the island for decades.

Park planners will avoid the pair’s territory when they release the new wolves, although there may be conflict. The park service will remain hands off once the wolves are released. “We intend to let [the wolves] work it out,” Green says.