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Wolves of Isle Royale

Ranger Steve’s Nature Niche

By Ranger Steve Mueller

Moose were free from large predators from the beginning of the 1900’s when they colonized the island. In the mid 1900’s, wolves were able to cross an ice bridge from Canada to Isle Royale National Park. The danger of moose living in a predator free habitat is that the population can grow to a level causing starvation when food becomes over browsed and depleted. That is evident for human populations in many places around the world. It was a reason for massive Irish immigration to America during the potato famine in Ireland. 

On Isle Royale during the last 70 years, wolves helped keep the moose population from becoming too large. By searching the Internet for Isle Royale wolves, one can find graphs showing moose population fluctuations relative to wolf numbers. A large moose population occurred after someone illegally brought a dog to the island and parvo virus spread into wolves and reduced their population. Later wolf numbers increased and declined again. The limited number of wolves interbred with relatives and weakened their genetic blood strain similar to what occurred with European royalty when they could only marry royalty chosen from a small population set. 

Mating with first cousins is not allowed because of the genetic dangers for the health of children. Where many unrelated individuals live, opportunity allows genes to spread through the population and maintain a healthy population. On the island, wolf gene exchange was limited. Climate warming now prevents ice bridge formation between Canada and the island making it impossible for wolves to naturally come to or leave the island. 

Inbreeding weakens the wolves. A female bore a male and later a female. The declining wolf population was reduced to two wolves. They were the offspring of the female. The male mated with his half-sister. Their offspring did not survive. That male has not been seen for over a year and has probably died. Aerial flights are used to inventory moose and wolf populations in winter. The male could have stayed out of sight but more likely he has died. 

I have wondered about the last remaining lone wolf on the island and how a pack animal handles living alone. Bringing down a large animal like a moose is a pack endeavor. Other animals like beavers are good prey but are not available in winter. Wolves develop emotional relationships with their pack. 

It is clearly evident that when I went away for a week, BeeGee, our dog, was lonely and did not eat for days. When I returned, his demeanor changed. He became excited and joyous in my arrival. Scientists caution us from applying human emotion to animals. BeeGee and I developed a friendship where I was his and he was mine. He was a family dog but, in our case, he and I developed an especially close emotional bond. 

The lone wolf on the island has continued life on her own with no breeding opportunity. This past fall, four wolves were trapped in Canada and released on Isle Royale. One was male and three were female. They are fitted with radio collars that will fall off in two years. Batteries will die before then. At present the collars track wolf movements. The four wolves have remained on the north side of the island. Research scientists hypothesize it is because the south side is occupied wolf territory. That is where the lone female lives. 

The male’s collar stopped moving. His dead body was located for necropsy (autopsy) to determine cause of death. Only three released females occupy the north side of the island and the lone female remains on the south side. More wolves will be released in coming years. Release of 30 wolves is planned. They will come from Canada, Minnesota, and possibly from Michigan’s Upper Peninsula to provide genetic variation. 

Some people think that humans should not release wolves, while others think it is essential to prevent moose devastation of habitats that will disrupt the survival for many plants and animals. Human-caused climate change is already preventing wolves from getting to the island. We are a part of nature niches and need to determine how we fit into the natural world scheme. In our yards we determine life and death of species by how we landscape. Our yard landscaping is not wolf management but it is important for the survival of plants, birds, insects, toads, frogs, salamanders, snails, and many mammals. Wild yards are beautiful with abundant life.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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