Isle Royale Wolf Pack Decimated By Deaths Of Three Wolves
June 15, 2012

Isle Royale Wolf Pack Decimated By Deaths Of Three Wolves

Lawrence LeBlond for

Researchers from Michigan Technological University studying the wolf population at Isle Royale National Park were bewildered as to why there was a significant decline in the numbers of wolves on the northwest island on Lake Superior during their 2012 Winter Study -- the population went from 16 to 9 in just one year.

After scratching their heads for months over the disappearances, the team received word in May that could explain at least some of the missing wolves: they reported today that the bodies of three adult wolves were found dead in an abandoned mine shaft, one of which was a young female, and one was an alpha male.

Biologist John Vucetich and wildlife ecologist Rolf Peterson said that the news deals a major blow to the wolf population on Isle Royale, as their study found only one female in nine remaining wolves on the island.

The grisly discovery was made by National Park Service biologist Ted Gostomsk. After receiving the news, Peterson and wife, Carolyn, went to investigate. They recovered and examined the remains of at least three specimens.

“We found there had been a real catastrophe in early winter, before we arrived on the island in January,” Vucetich said. “There were three dead wolves from the Chippewa Harbor Pack in the shaft: a collared male that we had been unable to locate this winter, an older male–maybe the alpha male–and a female born in 2011.”

“There is no way to know how the three wolves ended up falling into the pit, but very likely, accumulating snow and ice played a role in the accident,” he added. “We believe the incident occurred between mid-October and mid-January.”

The collared male was Romeo, whom the team was not able to locate during their winter study. They did note that they picked up the signal briefly once or twice, however. The drowned female and older male showed noticeable fat in their organs, indicating that they were not suffering from a food shortage.

The researchers explained that the young female´s death came at a critical time in the wolves´ history, as the shortage of females already represented a significant risk for extinction in the population. During a visit to the area in the spring, Vucetich and Peterson found an additional female in the Chippewa pack, easing the burden somewhat, yet there were no signs of breeding in that female.

The wolves, which have been on the island since the 1950s, could have their fate sealed if the females do not breed soon. The team said they do, however, believe that one female has mated, but will not know for sure until they see signs of the pups later this summer.

The Park Service is now debating on sealing off the mine, which was created in the mid-1800s by the Pittsburgh and Isle Royale Company, to ensure no other animals can be lost in this tragic way.

Park superintendent Phyllis Green said the mine find is only one of a number of incidents that have befallen the wolves on the island. In the 1980s, a contagious virus ravaged the wolf pack decimating the population, taking them from 50 to 12 individuals.

“Random events often play a large role in isolated island populations,” Green said in a Michigan Tech release. “Information from this event will serve to help us evaluate future management.”

Scientists and park officials are also debating whether more wolves should be brought in from the mainland, or if they should let nature take its course, then start off anew if and when the current population goes extinct.

It is believed that wolves made it onto the island by crossing an ice bridge in the winter during the 50s. Once arriving on the island they formed packs and were able to thrive with an overwhelming moose population, one of their main food sources. But scientists have also found that moose populations waned as well, which may have also lent to the decline of the wolf population.

Supported by the National Park Service (NPS), the National Science Foundation (NSF), Michigan Tech, and numerous private donors and field volunteers, the wolf-moose studies at Isle Royale National Park have been going on for more than 50 years, the longest continuous predator-prey study in the world.