Page 2 of 2 Previous
At age 3, she had left the pack into which she was born, which is normal behavior for a wolf, Peterson said.
"They disperse and look for vacant territory and an opportunity to mate," he said. "But she's been trapped on Isle Royale. She'd been traveling on her own for two years and never had pups."
Scientists long believed it was extremely rare for wolves to cross from the mainland to the park, but evidence is mounting that it has happened more than they realized — which would explain how the population has maintained some genetic diversity despite its inbreeding, Vucetich said.
Ice bridges in western Lake Superior were more common in the 1960s and 1970, and it's likely that wolves made the crossing back then, Peterson said. But they've become increasingly scarce as Great Lakes ice cover has shrunk in recent decades, contrary to the widespread cover this winter.
"That just isn't going to work very well" as a way to build Isle Royale's wolf numbers, he said. "Ice just is not forming the way it used to."
Green said it was too early to give up on ice bridges as a pathway, with some scientists predicting climate change will bring more extreme weather swings.
"Nature may yet provide course corrections," she said.