Moose and Wolves on Isle Royale


Isle Royale is home to both wolves and moose, which is not unusual. What is unique about the island having both animals is the wolves are the only predator, and the moose are their only prey. This is such a rare situation that scientists have been studying this predator/prey relationship for over 55 years.

How did these animals get onto isolated Isle Royale in the first place? Also, what have scientists learned from studying these populations?

Migration to Isle Royale

Moose have lived on Isle Royale since at least the early 1900s. How they got there is uncertain; most likely, they either swam over from mainland Ontario or were brought in by humans to be hunted. Of course, this was long before Isle Royale was made a national park; hunting is now illegal there.

The wolves are another story. During an especially harsh winter in 1949, a single pair arrived via an ice bridge from Ontario. Because the genetic pool was so small, nearly all of the wolves on Isle Royale suffer from the same spinal deformity. In 1997, some new blood arrived in the form of Old Gray Guy, who earned his name through his unusual light gray color. He was so active that by 2009, about 56% of Isle Royale’s wolves were his descendants!

Population fluctuation

When scientists first began studying the animals on Isle Royale, they expected that the populations would settle to around 1,500 moose and 25 wolves. To everyone’s surprise, however, that hasn’t been the case at all. The moose population has swung from a high of 2,450 to a low of 540. The wolves once numbered 50, but as of early 2017 are down to just two.

What is causing this? A big factor is the lack of genetic diversity. Every single wolf on the island, even the ones descended from Old Gray Guy, can be traced back to just one ancestor. Right now, the population has gone down to only two wolves, both of them with serious problems related to inbreeding. For the first time, the National Park Service is considering a plan to introduce 20-30 new wolves onto the island over the next three years to prevent the population from disappearing entirely.

The moose population is doing just fine and the fluctuations are mostly dependent on the food available to them. Whenever the moose population reaches a peak, they naturally consume most of the available forage, which then leads to a famine. The cycle then starts over. Scientists hope that if new, healthy wolves are introduced to the park, a more stable predator/prey relationship will develop and both populations will stabilize. Current population statistics can be found at The Wolves and Moose of Isle Royale.

See the wildlife of Isle Royale for yourself

On your next trip to Isle Royale, keep your eyes peeled while you’re out for a hike and you might be able to see one of these wolves or moose for yourself! You may even see one from the air while your seaplane is coming in for a landing. To start planning your trip, call (906) 483-4991 or send a message through our website to make a reservation.

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Hancock Portage Canal
Seaplane Base
21205 Royce Road
Hancock, MI 49930

Cook County Airport
123 Airport Road
Grand Marais, MN 55604

(906) 483-4991

Isle Royale Seaplanes


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