Results from the 61st annual winter survey of moose and wolves on Isle Royale show that moose numbers have climbed to an estimated 2,000, up from an estimated 1,500 last year.
This was the second highest total ever recorded by the team of researchers from Michigan Tech.
The only year the count was higher was 1996 when moose peaked at 2,445. Due to serious over browsing, the population crashed to about 700 the next year when many moose ran out of food and suffered from the effects of starvation.
As far as counting wolves, researchers knew exactly how many were on the island.
Fifteen wolves populate the 45-mile long island. Two of them, a father and daughter that are also half siblings, were the lone wolves left until 13 were transplanted from Grand Portage and Ontario last fall and this March.
Meanwhile, without any real predators, moose numbers soared and the vegetation on the western side of the island has been greatly impacted with tree growth stunted because of the moose over browsing.
Two Michigan Tech professors, John Vucetich and Rolf Peterson (now retired) who headed up the study, have spent much of their careers studying the predator/prey relationship between the moose and wolves on Isle Royal, keeping a Michigan Tech study going that began in 1958. This is the longest predator/prey study conducted anywhere.
While the wolf population declined from a high of about 50 in 1980 to two in 2016, the moose population has steadily risen.
A lack of predators prompted the national park service to conduct a study that took several years to complete.
That study involved the public before a decision was made to bring as many as 30 new wolves to the island to restore an ecological and predatory/ prey balance.
During the decision making process, the park developed a management plan that addresses the role in the island echo system of wolves and their relationship with moose (their preferred prey), the condition of island vegetation, and the effects of ongoing climate change.
Isle Royale National Park was established as a national park in 1940, and at that time there were no wolves living there.
The best guess is that the first wolves arrived mid to late 1940’s by walking over a 14-mile ice bridge between Lake Superior and land in Minnesota-Ontario.
Before any wolves were transplanted to the island wildlife scientists hoped some would come from the mainland via an ice bridge, but ice bridges work two ways. In 2013 one wolf left Isle Royale via an ice bridge, and in 2014 two wolves visited from the mainland but then returned back home. This past winter one of the transplanted wolves returned home to Grand Portage across an ice bridge.
Wolves nearly disappeared in the 1980s after canine parvovirus was introduced to the island by a dog. Their numbers further fell because of inbreeding and disease.
The island’s study has tracked how wolf and moose numbers have risen and fallen together over the years. As the number of moose has grown and wolves declined, mostly from fighting, disease, and inbreeding, the terrestrial vegetation is taking a hit as moose numbers climb.
Wildlife biologists are hoping the newly transplanted wolves will get together and produce offspring and help restore the moose population to a point where both predator and prey thrive. For that to happen, the predation rate should be in the 10 to 15 percent per year, but that will be a few years off until the new wolves have settled and formed social groups, or packs.
Isle Royale superintendent Phyllis Green said the park intends to add as many as 15 more wolves to the mix. The next translocation of wolves will be from Michigan in the fall, Green said.
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