page_title: Isle Royale National Park
section_title: Fauna
hierarchical_section_title: Isle Royale National Park / Natural history / Fauna
caption_attribution_description: English: Moose swimming off Isle Royale National Park
context_page_description: Isle Royale National Park is an American national park consisting of Isle Royale and hundreds of adjacent islands, as well as the surrounding waters of Lake Superior, in the state of Michigan. Isle Royale National Park was established on April 3, 1940, then additionally protected from development by wilderness area designation in 1976, and declared a UNESCO International Biosphere Reserve in 1980. The park covers 894 square miles, with 209 square miles of land and 685 square miles of surrounding waters. The park's northern boundary lies adjacent to the Canadian Lake Superior National Marine Conservation Area along the international border.
context_section_description: Isle Royale National Park is known for its timber wolf and moose populations which are studied by scientists investigating predator-prey relationships in a closed environment. This is made easier because Isle Royale has been colonized by roughly just one third of the mainland mammal species, because it is so remote. In addition, the environment is unique in that it is the only known place where wolves and moose coexist without the presence of bears.
  Historically neither moose nor wolves inhabited Isle Royale. Just prior to becoming a national park the large mammals on Isle Royale were Canada lynx and the boreal woodland caribou. Archeological evidence indicates both of these species were present on Isle Royale for 3,500 years prior to being removed by direct human actions (hunting, trapping, mining, logging, fires, competition for resources from exotic species and possibly disease due to the introduction of invasive species). The last caribou documented on Isle Royale was in 1925. Though lynx were removed by the 1930s some have periodically crossed the ice bridge from neighboring Ontario, Canada, the most recent being an individual sighting in 1980. Although lynx are no longer present on
  the island, their primary prey, snowshoe hares, remain. Before the appearance of wolves, coyotes were also predators on the island. Coyotes appeared around 1905 and disappeared shortly after wolves arrived in the 1950s.
  Moose are believed to have colonized Isle Royale sometime between 1905 and 1912. It was initially believed that a small herd of moose (moose typically do not travel in herds) colonized the islands by crossing the ice from the adjacent mainland; later this theory was modified to a herd of moose swimming 20 miles across Lake Superior from the nearest mainland. The improbability of these theories received little scrutiny until recent years. Although no thorough scientific investigation to determine how moose arrived on Isle Royale has been carried out to date, both cultural and genetic evidence indicates they were likely introduced by humans to create a private hunting preserve in the early 1900s. The cultural evidence that moose were trapped in northwestern Minnesota and transported to Isle Royale sounded far fetched to many until decades later when genetic evidence revealed the moose on Isle Royale were more closely related to moose in the far northwestern Minnesota/Manitoba border area than the mainland adjacent to Isle Royale in far northeastern Minnesota bordering Ontario. Further evidence has also shown that the Washington Harbor Club, a group of well-to-do businessmen, owned various buildings on Isle Royale in addition to railroads that ran from Baudette to Duluth and Two Harbors and so had the means to transport moose from northwestern Minnesota to Two Harbors.
  There are usually around 25 wolves and 1000 moose on the island, but the numbers change greatly year to year. In the 2006-2007 winter, 385 moose were counted, as well as 21 wolves, in three packs. In spring 2008, 23 wolves and approximately 650 moose were counted. However, recent reductions in winter pack ice had ended replenishment of the wolf population from the mainland. Due to genetic inbreeding, the wolf population had declined to two individuals in 2016, causing researchers to expect that the island's wolf population would eventually become extinct. At the same time, the island's moose population had exploded to an estimated 1600. By November 2017, the wolf population was down to one, a female.
  In December 2016, the National Park Service (NPS) put forward an initial plan in which they would bring additional wolves to the island in order to prevent the pack from disappearing completely. As of June 7, 2018, the decision to relocate 20-30 wolves to the island has been approved and the NPS is actively developing specific implementation strategies. There was some debate as to whether or not the introduction was an unnatural intervention.
caption: Moose swimming at Isle Royale.
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