Wildlife biologist Rolf Peterson holds up the antler of a moose. Peterson has been studying wolves and their prey on Isle Royale for more than 30 years. (Photo by Lester Graham)
It’s been a cold winter this year, especially for Rolf Peterson. Peterson is a wildlife biologist who studies wolves and moose on Isle Royale. Every year starting in January Peterson spends several weeks on the island at the northernmost spot in Michigan surrounded by the frigid waters of Lake Superior. The environment is harsh, but Peterson says it’s the best time to observe wild animals, and as the Great Lakes Radio Consortium’s Gretchen Millich reports… his research has uncovered some of our most basic knowledge about predators and their prey:
Transcript
It’s been a cold winter this year, especially for Rolf Peterson. Peterson
is a wildlife biologist who studies wolves and moose on Isle Royale. Every
year, starting in January, Peterson spends several weeks on the island, at the
northernmost spot in Michigan, surrounded by the frigid waters of Lake Superior.
The environment is harsh, but Peterson says it’s the best time to observe wild animals.
And as the Great Lakes Radio Consortium’s Gretchen Millich reports, his
research has uncovered some of our most basic knowledge about predators and their
prey:
Isle Royale National Park has been compared to a priceless antique… a place that
will be even more valuable in the future. It’s an isolated wilderness, where wolves are
free to hunt as they have for centuries, protected from the threat of humans. No one is
more aware of the value of Isle Royale than Rolf Peterson, a wildlife biologist at
Michigan Tech University. Peterson has spent much of his life on this island. The
attraction for him is that humans are not in charge. It’s wolves, moose and other wild
animals that have the run of the park.
“In this particular place, society has said we’ll just let things go and do whatever
they do. And that could happen now really only in a national park. This happens to
be an island national park, so it has all the attributes which make it a real natural
outdoor laboratory.”
The study of wolves on Isle Royale was started by Durwood Allen of Purdue
University in 1958. In 1970, he chose Peterson, a graduate student, to help him
wrap up the program. But Peterson didn’t end the study. Instead, he made it his
life’s work. Right now, Peterson is on Isle Royale, tracking the wolf packs and
checking to see how many moose they have killed. This technique only works
in the winter, when the trees are bare and Peterson can follow wolf tracks in the snow
from an airplane.
“The anticipation peaks in January when we finally get here and take those first
couple flights to see what’s happened in the past year. You know which
packs are still here, are they going up or going down. Each year it’s a brand new
revelation, almost guaranteed.”
Wolves first came to Isle Royale in 1949 – by crossing the ice on Lake Superior.
There they found a moose population with no natural predators.
For many years, Peterson believed that the size of the moose population was driven
only by their food supply and the condition of their habitat. But in the 1980’s, he made
one of the most important discoveries about predators in the wild.
“It wasn’t until events during the 1980’s in which wolves either went up real fast or
down real fast and the moose population responded in inverse fashion that
I realized – wow, wolves really do make a difference in many cases. So now
I tend to think that wolves are one of the primary drivers of population change
in their prey.”
What Peterson observed was an interdependency between predator and prey: Moose
provide food for wolves, while wolves prevent overpopulation in the moose herd by
hunting the old, the young and the sickly. It’s an idea that has had implications
in areas around the world, where moose are hunted by humans.
“The wolf has really shaped moose as we know it and in places where we use moose
consumptively, the more we can adopt the harvest patterns of wolves, the more
productive our use of moose will be, because this is the pattern that moose have evolved
with for millions of years.”
Peterson’s family shares his fascination with wildlife. His wife Candy and their
two sons have spent many summers on Isle Royale, looking for wolf and moose
carcasses to add to Peterson’s bone collection.
But during the winter, it’s only Peterson and his assistants who brave the cold of this
wilderness to follow wolf tracks in the snow. Peterson says he intends to
follow those tracks and the interaction between wolves and moose on
Isle Royale for many years to come.
For the Great Lakes Radio Consortium, this is Gretchen Millich.