Mystery of missing Northland wolves solvedScientists studying the wolf population on Isle Royale were told of a grisly discovery in late May that could explain the reason for a dwindling number of wolves on the island.
By: Mike Creger, Duluth News Tribune
Scientists studying the wolf population on Isle Royale were told of a grisly discovery in late May that could explain the reason for a dwindling number of wolves on the island.
An alpha male, another male and a female were found dead in a mine shaft on the large Lake Superior island by National Park Service staff.
In a winter study released in March, biologist John Vucetich and ecologist Rolf Peterson from Michigan Technological University reported that they thought Isle Royale’s gray wolf population faced extinction because only nine of them remained. It was a mystery as to why they were dying off.
A dwindling moose population was blamed, because moose are the main food source for the wolves. The researchers also guessed inbreeding and a shortage of female wolves were playing a part.
“We now understand a major reason for the decline in pack size,” Vucetich was quoted in a news release from Michigan Tech.
He believes the wolves fell into the water-filled shaft sometime early in the winter, before his team arrived in January for its annual seven-week study.
One wolf was a collared male the team had been looking for. The other male was believed to be a pack leader, or alpha male. The female was born last year.
Loss of the alpha male can leave a pack rudderless, Vucetich said, it’s “why we saw such a desultory pattern of travel and low kill rate in this pack.” He said the pack seemed to have no “game plan” as his team watched them in January.
The Park Service will explore sealing off the mine before similar incidents occur.
The mine shaft was created in the mid-1800s.
Park superintendent Phyllis Green said the mine find is just one of a number of incidents that have befallen the wolf packs there. In the 1980s, they were ravaged by a contagious virus, taking the population from 50 to 12.
“Random events often play a large role in isolated island populations,” Green said in the Michigan Tech release. “Information from this event will serve to help us evaluate future management.”
Park officials and scientists have been debating whether they should interfere by adding wolves from the mainland to the pack or let it die off and start anew.
Wolves are thought to have crossed an ice bridge in the 1950s to the Lake Superior island just east of Grand Portage. They eventually formed packs and kept in check what had been an overwhelming moose population. Because of fewer winters when the lake freezes over, the pack has become even more isolated.
The Tech scientists will gather what information they can from the bones of the three wolves.
It isn’t known if a litter of pups were born this spring. The team noticed the lone female had a mate.
The moose population is also up, another hopeful sign for the pack.
The Associated Press contributed to this report.