A 5-year-old female wolf who crossed an ice bridge from her home on Isle Royale was found dead near Grand Portage.
Michigan Technological University biologist Rolf Peterson tells the Associated Press the cause of death was not immediately clear and an autopsy is planned.
The radio-collared wolf had been named Isabelle by researchers who for decades have used the island in Lake Superior as a laboratory to study the predator-prey relationship between wolves and moose.
Concern about the future of Isle Royale's wolves has grown as the population has shrunk. The AP says wolf numbers fell to 8 last year, down from 24 five years earlier.
An article published in the magazine Nature this month explains that some scientists – including the two biologists now leading the Isle Royale study – favor transplanting other wolves onto the island to replenish its inbred population.
Other researchers disagree and think nature should be given more time to run its course. Wolf expert David Mech of the U.S. Geological Survey told the Star Tribune this month the wolf numbers on the island could still rebound, pointing to the recent birth of new pups there.
The AP story says three pups survived their first few months at Isle Royale but the deaths of Isabelle and another adult would put the population at nine.
Unless, of course, wolves other than Isabelle have made use of that ice bridge this winter. An editorial in the Chicago Tribune Monday expressed hope that mainland wolves from Minnesota or Ontario would make their way to Isle Royale, which is a national park. The Tribune says ice connections to the island were once common but have become more scarce, with 2008 being the last winter that offered one.
With Lake Superior 90 percent ice-covered this winter, the idea of Isle Royale wolves mingling with mainlanders has captured some imaginations. In a tongue-in-cheek article last week a writer for MinnPost explained that an NSA connection helped him track down the radio frequency of Isabelle and conduct a telephone interview with the wolf as she visited a Thunder Bay restaurant. ("Suffice it to say, I'm 5 years old now and the clock is ticking.")
Michigan Tech's Peterson tells the Star Tribune that the dwindling wolf numbers threaten Isle Royale's ecosystem. There's been an explosion in the moose population, which Peterson says has doubled since 2006 and now sits near 1,000. Moose feed mainly on balsam fir. If that tree disappears from the island it's unlikely that either moose or wolf would survive, he says.