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Iconic wildlife populations are declining on Isle Royale

Scientists at Michigan Technological University have uncovered new information on two iconic wildlife populations that inhabit Isle Royale – an island of the Great Lakes located northwest of Lake Superior. 

The researchers found evidence that wolves are thriving in the region, while the moose population appears to be in a state of decline.

The COVID-19 pandemic canceled the wintertime survey of wolves and moose on Isle Royale for the first time in 63 years. The MTU team visited the remote national park in the spring, gaining new insights into wolf and moose abundance. The experts report that the Isle Royale wolf population is likely growing. 

“We recovered footage of a group of four wolf pups taken in January 2021 by remote cameras at the east end of Isle Royale,” said Professor Sarah Hoy. “Additionally, observations of tracks and scats left by wolf pups last fall at two different locations suggest that there were probably two different litters of pups living at the east end of the island in September 2020.”

“Wolf foraging behavior seems driven by minimizing the risks associated with killing large prey, like moose, even when the differences in vulnerability among individual moose might seem relatively subtle compared to when predators are choosing between different prey species.”

The moose population is particularly sensitive to nutritional stress, which has concerning implications for how the animals will respond to a warming climate. 

“We found that the nutritional health of moose was importantly influenced by how hot it is during the summer, and also by how deep the snow is in winter,” said Hoy. “Moose tended to be more nutritionally stressed during winters with deep snow, which may be because deeper snow makes it more difficult for moose to move around and find food.”

The moose population is likely declining, and Hoy noted that moose really struggled to find enough food this past winter. 

“Because there have been such large numbers of moose on the island over the last five years and moose ate branches faster than the trees can recover and replace them, the amount of food available to moose during winter has been getting progressively worse each year since 2017.”

The study is published in the journal Animal Behaviour.

By Chrissy Sexton, Staff Writer

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