Wolves and moose on Isle Royale

A pack of wolves hunting a moose on Isle Royale, 1966

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 since 1958. Isle Royale, the principal island of Isle Royale National Park in Michigan in the United States, is an isolated island with little migration 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. 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[1] to down to two.[2][3] From 2018 to 2019, 19 wolves were released at Isle Royale in hopes of bringing stability to the ecosystem, and as of 2020, there are estimated to be 14 wolves remaining on the island.[4]

The relationship between wolves and moose on Isle Royale has been the subject of the longest predator-prey research study, begun in 1958.[5] The wolves have been subject to inbreeding and carry a spinal deformity.[6] As of the 2014 count, there were only 9 wolves on the island,[7] with the 2015–2017 counts showing only 2.[8][3][9] A review completed in 2014 determined that new wolves would not be introduced into the park to attempt a genetic rescue,[10][3] but as of December 2016, the National Park Service had instead decided to introduce 20 to 30 wolves to the island. In 2018, three females and one male wolf from Minnesota were transferred to the island system.[11]

Isle Royale National Park is made up of about 400 islands, and is in the northwest portion of Lake Superior. It is about 50 miles (80 km) from Michigan's shore, and 12 miles (19 km) from the Canadian shore. The main island is about 45 miles (72 km) long, and nine miles (14 km) wide at the widest point, with an area of 205 square miles (530 km2). There are no roads, and no motorized vehicles are allowed on the island.[12] The park is closed from September to May during which the wolf-moose study personnel are the only human residents on the island.

  1. ^ "About The Project: Overview". The Wolves and Moose of Isle Royale. Retrieved April 11, 2015.
  2. ^ "Wolves - Isle Royale National Park (U.S. National Park Service)".
  3. ^ a b c Kozlowski, Kim (April 11, 2016). "Just 2 wolves left on Isle Royale". The Detroit News. Retrieved April 18, 2016.
  4. ^ "Summary report 2018-2020. Wolves and the Isle Royale Environment" (PDF). National Park Service. Retrieved February 12, 2023.
  5. ^ "Overview of the Ecology and Research of Wolves and Moose on Isle Royale". The Wolves and Moose of Isle Royale. Archived from the original on December 8, 2006. Retrieved April 16, 2006.
  6. ^ Isle Royale pack down to 2 female wolves by John Myers March 30, 2011 Duluth News Tribune newspaper
  7. ^ Rebecca Williams (January 6, 2015). "Isle Royale researchers take to the air for bird's eye view of wolves and moose". Michigan Radio. Retrieved April 10, 2015.
  8. ^ Two wolves survive in world's longest running predator-prey study, Science, Retrieved September 7, 2017: https://www.science.org/content/article/two-wolves-survive-world-s-longest-running-predator-prey-study
  9. ^ Flesher, John (April 17, 2015). "Scientists say Isle Royale National Park gray wolf population down to 2 and may soon die out". U.S. News & World Report. Retrieved April 18, 2015.
  10. ^ Lisa Kaczke (March 11, 2015). "Pair of wolves cross to Lake Superior island, but no success in breeding". The Dickinson Press. Retrieved April 10, 2015.
  11. ^ "Isle Royale wolf relocation". Detroit Free Press. Retrieved January 3, 2019.
  12. ^ "Ranking Report for Recreation Visits in 2008". National Park Service. Archived from the original on May 3, 2015. Retrieved August 20, 2009.