Scientists: 2 mainland wolves made jaunt to Isle Royale park

Published 10:19 am Wednesday, March 11, 2015

TRAVERSE CITY, Mich. — Two gray wolves recently traversed the frozen Lake Superior surface from Canada to Isle Royale National Park, scientists said Tuesday, but the animals stayed only five days — dashing hopes that ice bridges would induce migrants from the mainland to replenish the island’s lagging wolf population.

One wolf was a female that had been fitted with a radio collar last year, enabling biologists to trace her movements. The other was smaller — perhaps an offspring of the female. There is no evidence that either mated during their short time at the island park, said Rolf Peterson, a Michigan Technological University scientist who studies wolves and moose there.

Scientists have long believed wolves first made their way to Isle Royale in the late 1940s by crossing ice that forms during particularly cold winters. They found a plentiful food supply in the moose that inhabit the archipelago in northwestern Lake Superior.

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The wolf population has averaged 23 but has fallen drastically in recent years because of inbreeding, disease and a temporary moose shortage, scientists say. Only eight were counted in 2013, the least since the 1950s. Last year’s total was nine.

Peterson and his Michigan Tech colleague John Vucetich recently completed their annual wolf and moose census. Peterson declined to discuss the findings Tuesday but said a report would be released in coming weeks.

It was disappointing that the two wanderers didn’t remain at the park, said Seth Moore, biology and environment director for the Grand Portage Band of Lake Superior Chippewa in Minnesota, which collared the female. Ice between Isle Royale and the mainland has broken apart and, with temperatures moderating, is unlikely to re-form this winter.