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An icy arena for predator and prey

Fifteen wolves and 2,060 moose. Extensive ice and deep, powdery snow. In its 61st year, the Winter Study report is the longest running examination of a predator-prey relationship in the world. The report chronicles the four-week research expedition to Isle Royale in Michigan, 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. 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% 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% ice cover. Credit: Sarah Hoy

Visit Website | Image credit: Sarah Hoy