Isle Royale Winter Study: 13 New Wolves, 20 Radio-collared Moose

One of the newly introduced gray wolves picks its way through deep snow on Isle Royale. (Photo ©  Rolf Peterson and courtesy Michigan Tech News)

By Kelley Christensen, Michigan Tech Science and Technology Publications Writer
Posted April 30, 2019, on Michigan Tech News
Reprinted here in part with permission

Michigan Technological University’s 2019 Isle Royale Winter Study focuses on the implications of newly introduced wolves and the movements of newly collared moose.

Fifteen wolves. 2,060 moose. Extensive ice and deep, powdery snow. Michigan Tech researchers have released the annual Winter Study report. In its 61st year, the study is the longest running examination of a predator-prey relationship in the world.

The report chronicles the four-week research expedition to the island, where researchers track -- by ski and plane -- wolves and moose, collar moose, and catalog the cascading effects of an ecosystem that has lacked a healthy population of apex predators for a number of years.

New Tracks in the Snow

Prior to this fall and winter’s wolf reintroductions, the wolf population on the remote island had remained at just two -- a strongly bonded, but also highly inbred male-female pair -- for three years. The moose population, lacking predation, expanded by an average of 19 percent each year during the past eight years since 2011, when the wolf population first dwindled to fewer than 10. Consequently, primary plant species in moose diets -- balsam fir and watershield -- dropped precipitously.

The National Park Service (NPS), after an extensive review process, decided to introduce new wolves to the island. In September and October 2018, NPS introduced four Minnesota-born wolves (one male and three females) to the island. In late October, the male wolf died and on January 31, 2019, one of the female wolves left the island by crossing the ice bridge that had formed on Lake Superior, which reached nearly 95 percent ice cover.... Click here to read the rest of this article on Michigan Tech News.

Inset photo: Lake Superior reached approximately 95 percent ice cover during the 2018-19 winter. One of the introduced female wolves from Minnesota, used an ice bridge to leave Isle Royale in late January. (Photo © Sarah Hoy and courtesy Michigan Tech News)