Anderson: Wolf researcher’s new book explores predators, prey on Isle Royale

Dennis Anderson


Renowned Minnesota wolf researcher Dave Mech was in his early 20s and a graduate student at Purdue University when he arrived on Isle Royale in 1958 to study the predator-prey relationship between wolves and moose. Mech’s three-year groundbreaking project detailed for the first time the killing efficiency of wolves and the vulnerability of moose on the 210-square-mile Lake Superior island.

Now in a compelling new book to be launched Tuesday titled “Wolf Island: Discovering the Secrets of a Mythic Animal,’’ Mech, along with Twin Cities co-writer Greg Breining, chronicles Mech’s life and times on Isle Royale — camping, hiking and observing from a single-engine airplane how wolves and moose interact in their constant struggle for survival.

Q What is unique about Isle Royale’s predator-prey relationship between wolves and moose?

A It’s the only place where there is one large prey animal and once predator. This is unique in the world. In summer on Isle Royale, the beaver comes into play as prey animal for wolves. But there are no deer, bears or caribou, for example, to complicate the study of wolf predation.


Q How many moose are on the island?

A During the three years I was there, between 500 and 600. Since then the herd has varied between 1,000 and 2,000.


Q What types of moose do wolves typically kill on Isle Royale?

A Wolves generally don’t take just any moose, a fact that has been demonstrated elsewhere as well. Most often, they end up with calves, older animals and moose that are debilitated due to parasites, broken bones or for other reasons. I was able to confirm this by aging the moose that were killed by wolves.


Q You followed a pack of 15 wolves throughout your three years of study. How frequently would that pack kill a moose?

A They were able to kill every few days. The density of moose on Isle Royale is probably the highest in the world, and in different settings wolves may have to hunt longer than that. A wolf can go months without eating. If they can’t find a prey animal near them, they will continue to search far and wide. Wolves also will cache parts of a kill to eat later. Sometimes they bury food a mile from a kill and dig it up when they need it.


Q Killing a moose every few days or so seems to indicate a high degree of predator efficiency.

A In fact, only about 7% of hunts by wolves were successful. This rate applies to winter hunts. Even after all these years, we’re not sure of the success rate of summer hunts.


Q How do moose fend off an attack by 15 wolves?

A Usually, by just standing their ground. If a moose is healthy and just stands there and defies the wolves, the wolves will often give up. In that case, there’s not a lot of kicking by the moose. If a moose runs, wolves have a better chance, even

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