Wolves of Isle Royale offer unique opportunity to learn about predator-prey relationships

The American wolf population is declining, providing us an opportunity to understand predator-prey relationships.

A photo of a woof standing in the woods

The relationship of wolves and humans in the United States has been tumultuous.  Prior to European settlement, wolves inhabited much of the North American continent.  They were systematically eradicated, as settlers made their way west, being perceived as a threat to families and livelihoods.  Habitat was also destroyed as part of the westward expansion, further stacking the deck against wolf viability.  Today the American wolf population is a mere shadow of what it once was.

Whether you love them or hate them, studying wolves can be a great way to observe some of the dynamics that occur with any predator-prey relationship in nature.  When it comes to wolves, there is perhaps no better place to learn about this relationship than on Lake Superior’s largest island, Isle Royale.

The island is part of Isle Royale National Park (actually one large island surrounded by many smaller islands), which protects about 450 square miles.  In the late 1940s, wolves established themselves on the island via an ice bridge from Ontario.  Since that time, biologists have been studying the interaction of the wolves and their primary prey source on the island, moose, making this the longest ongoing predator-prey research study in the world.

Researchers have observed the species dynamics and collected data throughout the years, seeing the wolf and moose populations fluctuate dramatically.  At times, the wolf population on Isle Royale numbered as high as 50.  High levels of predators mean that the prey populations (moose) are kept in check.  Conversely, when the wolf populations were low, moose populations increased.  Similarly, when moose populations are high, their food sources—balsam fir, aquatic plants—are impacted.

In 2016, the Isle Royale wolf population had dwindled to two animals, sparking a debate among scientists as to what to do next.  On one hand, if new wolves were brought in, this long-running predator-prey study could continue.  On the other hand, if new wolves are brought in, is the study still valid (since humans have now altered the variables)?  In the end, the National Park Service decided to start introducing new wolves to the island in 2018, thus continuing the study.  Up to 30 more wolves will be brought in over the next three years. 

Michigan State University Extension natural resource educators can offer more insight into predator-prey relationships.


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