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Continued: Bitter winter, pup survival alter Isle Royale wolf debate

Isabelle was born in 2008 to one of the two packs on the island, but, as wolves often do, left the pack in 2012 to find a mate. The pickings are few — and all the males are related to her. That inhibits mating in wolves as well as people, Peterson said.

In addition, lone wolves are vulnerable to attacks from breeding packs in the relentless competition for the right to reproduce.

Because she wears a tracking collar, the researchers have been able to follow her lonely and persecuted life. Last year they saw three other wolves chase her to the edge of the water and attack her with all the ferocity they use to bring down a 900-pound moose. They left her wounded and bleeding on the edge of the ice. When the researchers left last winter, they weren’t sure if they would see her again.

“But she has survived,” Vucetich announced on the research study’s blog in late January. “It would not be surprising if she’s learned to kill moose by herself. A wolf that can do so is better than most.”

Isabelle is now 5, a prime age to mate. About one in 10 wolves will strike off on their own and try to start new packs, and some will travel for hundreds of miles in their search. On Isle Royale, however, the wolves are trapped — unless there is an ice bridge.

No one knows what’s in the heart of a wolf, but Peterson said he thinks it’s quite possible, that given the chance, Isabelle will head out. Mech said that as long as there are potential mates on the island, she’s more likely to stay put.

The chances that a wolf would come from the mainland are also very small, researchers said. It’s known to have happened only three times in the island’s history. And today mainland wolves face a treacherous path across roads, yards and urban areas — never mind 20 miles of shifting ice.

Still, the survival of the three pups and the renewed possibility of ice bridges may have bought the National Park Service some time. Phyllis Green, park superintendent, is weighing three options: doing nothing, reintroducing wolves if their numbers hit zero or a “genetic rescue” by bringing a few new wolves to mate with those that are in residence.

Peterson and Vucetich said they favor genetic rescue. And Isabelle, if she had a vote, would likely agree.

 

Josephine Marcotty • 612-673-7394

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  • COURTESY OF JOHN VUCETICH. In the upper left, the male and female alph...

  • Isabelle, a five-year-old female, is not attached to either of the two packs on Isle Royale.

  • In the upper left, the male and female alpha wolves of this pack on Isle Royale rebuked one of their new pups born last year on the island. Researchers, who say this winter critically helped the survival of at least two and perhaps three pups born last spring to the alpha pair, believe that one of the other two pictured wolves is also one of the new arrivals.“Those wolves are not nonreproductive. In another year or two they could produce some more.”David Mech, a wolf expert with the U.S. Geological Society in Minnesota

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