The single predator-single prey relationship between wolves and moose on Isle Royale in Lake Superior is unique, and has been the subject of detailed study for over 50 years. Isle Royale, the principal island of Isle Royale National Park in Michigan in the United States, is an isolated island with little of animals into and out of the island, and as a national park, human interaction and impact on the two species is also limited. Both the wolves and the moose first became established populations on Isle Royale in the 1900s. Over the fifty years of the study, the populations of both moose and wolves have shown repeated spikes and declines and have not settled to a balanced relationship. The moose populations have ranged from 500 to 2500 while the number of wolves has ranged from almost 50 to down to two. As of 2018, wolves are being released at Isle Royale in hopes of bringing back the wolf population.