Isle Royale's 2 remaining wolves still alive, spotted this winter

They're still there.

Two wolves, half-siblings and father and daughter — an inbred, genetic tangle that probably should have contributed to their demise long ago. But for the third straight year, the last two wolves on Isle Royale in Lake Superior have continued to cling to existence.

The wolves were spotted again this winter during the annual winter study of wolf and moose populations by researchers from Michigan Technological University, on the more than 200 square-mile island that's part of a national park in Lake Superior.

The father is now 9, his daughter/half-sister is 7, said Michigan Tech wolf researcher John Vucetich.

"They are not in their prime anymore — they're old wolves now," he said.

More: Gold mine of potash sits beneath Michigan, could be worth $65 billion

More: Great Lakes still impacted by Ice Age phenomenon

Wolves came to Isle Royale more than five decades ago by crossing a frozen Lake Superior in winter. The island's wolf population once reached 50 wolves, and averaged 25 wolves over decades, before a population crash in recent years because of the physical and reproductive impacts of inbreeding. Changing weather patterns, leading to fewer and smaller ice-overs of Lake Superior, have meant fewer ice bridges between the island and mainland to potentially replenish the wolf population.

The remaining father-daughter pair have seen their pack die around them. They produced a pup one recent year, but it died within a year.

It's meant little to no predation on the island's abundant moose — and, in turn, a moose population boom. The moose count from this past winter's study was 1,475 — down from the 1,600 count the previous winter, though that could be attributable to a slight overestimation that season, Vucetich said.

"The bigger trend, for seven years now, is the moose population growing at 16% per year," he said. "The moose population can double in four or five years at that rate. They have done so over the past four or five years, and will do so again if current trends continue."

With the moose's voracious appetites — one adult moose can eat up to 60 pounds of plants per day — an unchecked moose population could dramatically alter Isle Royale's ecology for the worse. And that could one day soon lead to a massive moose die-off.

"I think we're on a knife's edge," Vucetich said.

"If wolves don't get it back together soon, if wolf predation isn't restored promptly, a severe winter could just make (a large-scale moose die-off) happen. But even absent a severe winter, the bottom could just drop out of the food supply at some point."

After years of debate and study, the National Park Service in March announced it was moving forward with plans to put 20 to 30 wolves from the mainland on Isle Royale over three years, a "genetic rescue" long advocated for by Vucetich and his fellow Michigan Tech wolf researcher, Rolf Peterson.

The process of physically re-introducing wolves could begin as early as this fall, depending on the availability of funding and the procuring of suitable wolves, Phyllis Green, the superintendent of Isle Royale National Park, said in March.

The bureaucratic process may produce a rescue too late for the remaining wolf pair — and possibly too late to stop a moose die-off, Vucetich said.

"If you wanted to make sure this didn't happen, you really needed to act four or five years ago," he said. "Now, it's a probabilities game. We just have to wait and see."

Michigan Tech Assistant Research Professor Sarah Hoy has studied the skull size of the island's moose, and found it decreased by 16% over 40 years.

Read more:

"Although the effects on body size are quite subtle, there was a marked decline in lifespan over the study period," she said.

Impacts on the moose go beyond wolves, also involving changes in fauna, particularly balsam fir, a staple winter food for moose, Hoy said.

"Maybe the trees can withstand one major source of stress, but with the lack of predation and changing climate, can it withstand two or more?" she said.

Peterson, who has been part of the Isle Royale study for the last 50 years, said the island provides a unique place to study moose and wolves, a neatly contained ecosystem that provides insights into other north woods settings.

"This is the perfect environment to observe predatory-prey interactions — but that doesn't make it easy," he said.

Contact Keith Matheny: 313-222-5021 or kmatheny@freepress.com. Follow on Twitter @keithmatheny.