Wildlife ecologist Rolf Peterson and fellow research scientist John Vucetich, both of Michigan Technological University in Houghton, found Isle Royale’s two remaining wolves sitting on the ice, feeding on a freshly killed moose calf this January. The wolves looked healthy and had a sea of moose to hunt.
The moose kill was one of four the two researchers could attribute to the wolves as they conducted the 59th winter moose/ wolf predator-prey study for Michigan Tech, which was released in late April.
This research is the longest continuous study of any predator-prey system in the world.
Wolves came via ice bridges that formed during cold winters from Canada sometime in the late 1940s. In 1980, it was estimated that there were 50 wolves on the island, and as recently as a decade ago, 30 wolves prowled the national park.
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, according to the study’s 59th annual report.
A seven-year-old female and nine-year old male gray wolf are what is left of the wolf packs that once roamed the island. With an estimated 1,600 moose herd growing at a rate of 20 percent per year over the last six years, scientists are worried that the moose will over browse and destroy much of the vegetation on the island.
No further wolf pups are expected from the two remaining wolves.
Attempts by the male to breed with the female failed, noted the researchers, when the female rebuffed the male, baring her teeth, during the breeding period. The male is both the female’s father and half-sibling. One pup they did have died after living for about one year. The pup had trouble walking because of deformities to its spine (and other issues) caused by inbreeding.
Currently, the National Park Service is assessing about 5,000 public comments on its proposal to introduce 20 to 30 wolves to the island to establish a new population. A decision on that plan is expected by the end of this year.
Since the steady decline of wolves over the last half dozen years, researchers have noted beaver and moose have tripled, undoubtedly because of lack of predation, noted Vucetich.
The two wolves appear healthy and still have all their canines, something necessary for the survival of carnivores. The pair has already far exceeded the four-year average lifespan of wolves in the wild, escaping the two causes of death that took down their wolf packs: battles with other wolves and starvation.
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