Isle Royale National Park in Michigan is a wild, remote island in Lake Superior that serves as a natural refuge for wildlife, including its most famous residents: wolves and moose. Ninety-nine percent of Isle Royale is designated as a federal wilderness area and as the island’s top predator, wolves are essential to controlling the island’s moose population.
However, the wolf population has been slowly dwindling for several years, getting down to just two wolves by 2018 that were incapable of breeding or keeping the population of over 1,500 moose in check. In order to restore balance, NPCA supported the National Park Service’s bold plan to bring 20 to 30 new wolves to Isle Royale. This plan is underway with 14 wolves now hunting and breeding on the island, contributing to a decline in the moose population for the first time in nearly a decade.
The interplay between the island’s wolves and moose has been the subject of a study that has stretched across both decades and generations. Begun in 1958, it is the longest predator-prey study in the world. Through this unique study, researchers have tracked the ebb and flow of both populations, and it became clear that the near elimination of wolves on the island resulted not only in a surge in the moose population but dangerous ripple effects for the island’s vegetation. Without predators, the moose population rapidly increased and so did the amount of native plant species they were consuming.
The decline in wolves was driven in part by a virus inadvertently introduced by a hiker’s dog, which spread through the wolf population, cuttings it ranks from 50 down to 14 in 1980. However, the virus that struck the wolves was only exacerbated by the fact that fewer wolves were naturally migrating to the island. Historically, ice bridges formed on Lake Superior from the island to the mainland for more than 50 days a year, allowing wolves ample time to migrate. Over the last 20 years, these bridges have been far less common and consistent, essentially cutting off natural migration.
A sustainable solution
The wolf population at this remote Michigan park has been dwindling for years. A new plan, supported by the island’s eminent researcher, will benefit the animals and the ecology of…See more ›
As the wolf population plummeted, the National Park Service relied on an extensive environmental analysis, consulted scientists and gathered public input to determine a sustainable long-term approach to this crisis. On June 7, 2018, the Park Service released a long awaited Record of Decision calling for the introduction of 20-30 wolves over a three-to-five-year period.
NPCA has long believed that wolves are critical to maintaining a healthy landscape at Isle Royale National Park. We supported this carefully considered plan that will ensure this iconic species won’t disappear from the park and deprive the ecosystem of one of its key links.
Soon after the Park Service announcement, staff began putting the restoration plan in motion, with the arrival of four wolves from the Grand Portage Indian Reservation in Minnesota during fall 2018. The Park Service then partnered with the Ontario Ministry of Natural Resources and Forestry to transport more wolves from Canada in winter 2019, making this an international effort. The Park Service then worked with the Michigan Department of Natural Resources to bring additional wolves to the park in fall 2019. All the new wolves were captured in the wild, carefully transported to the park and set loose on the island with tracking collars to help researchers monitor their movement.
Fourteen wolves, including new pups, are now estimated to be on Isle Royale National Park, up from just two that remained when the National Park Service began to implement the wolf restoration plan!
Check out one of the newest arrivals stepping foot on the island and visit the Park Service website for regular photos, videos and other updates about the wolf relocations.
The Park Service and its partners continue to monitor the wolf population to determine evidence of social organization, reproduction and predation. In September 2020, the National Park Service and the State University of New York-College of Environmental Sciences and Forestry (SUNY-ESF) released a summary of the wolf recovery efforts, which estimates 14 wolves are now on the island and confirms wolf pups were born in 2019 and 2020. The annual winter study conducted by researchers with Michigan Technological University continues, with the most recent study results released in September 2020. The island’s wolves are grouping up, staking out their territories and hunting moose, contributing to a decline in the moose population for the first time in almost a decade.
Research has documented other signs of progress as well. The Park Service and the State University of New York – College of Environmental Science and Forestry released a study in December of 2019 that confirmed the new wolves are hunting moose. Using collar data, researchers found the remains of 60 prey, which included moose, beavers and snowshoe hares, but in a positive sign, over half of the prey were moose. This confirms what scientists predicted, and what we hoped for — these new wolves are adjusting well, feeding on the overly abundant moose.
Additional research confirmed that the introduced wolves are feeding, traveling, sleeping close to one another and forming groups. This has also led to wolf-on-wolf aggression that resulted in the deaths of two wolves, including one of original pair. These events are not uncommon as wolves defend and establish their territories and social hierarchy. Although wolves are traveling together, researchers say they are not defined as a “wolf pack” until a breeding pair reproduces.
As the wolves adjust to their new home and the study continues to track their numbers, we are hopeful that Isle Royale will once again have a thriving wolf population.
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