Louise Knott Ahern

lkahern@lsj.com

A year after award-winning LSJ story%2C no sign of new wolf pups spells trouble for Isle Royale wolves

Researchers found no evidence of wolf reproduction over the summer

The number of moose on the island has doubled to more than 1%2C000

Isle Royale was designated a National Park in 1940%2C before wolves were on the island

Another season at Isle Royale National Park will end in two weeks, leaving the island park closed to visitors until next spring.

But as the last boat pulls away to cross Lake Superior, it will leave behind an endangered population of wolves which, for only the second time in more than four decades, has apparently failed to reproduce.

Scientists who study Isle Royale wolves and moose in a famed 55-year research project say they found no evidence of new wolf pups during their summer stay on the island.

The finding — or lack thereof — is significant because it's one more sign the island's iconic wolves are struggling to survive following generations of inbreeding, disease and isolation. The only other time the wolves did not reproduce was in 2012.

Researchers caution that lack of evidence does not definitively mean the wolves didn't reproduce this year. It just means it's unlikely, said John Vucetich, a Michigan Technological University professor and principal researcher on the Wolf-Moose Project.

"There are usually signs," Vucetich said. "You might hear the pups howling. By late summer or early fall, it's not uncommon for a visitor to have taken photos. We didn't see any of that."

He said they won't know for sure until the research team returns to the island in January for their annual winter study, when snow cover makes it much easier to spot the animals.

"There is still possibility we'll see reproduction," he said. "They would be nine-month-old pups in January. If we do, it would be very good news. But it's a bad sign that we didn't see any signs this summer."

Only nine wolves remain on Isle Royale today, down from a high of 50 in the early 1980s. Scientists blame a variety of factors for the wolves' decline, including climate change.

Lake Superior used to freeze on average every other year, allowing wolves to move back and forth between the island and Canada. Today, the lake only freezes every 15 years or so — including last winter — as the average lake temperature as risen by 4 degrees.

The isolation has forced the wolves into generations of inbreeding. Every wolf on the island is now related in some way and has the health problems to show for it.

Researchers have not found a wolf carcass with a healthy spine in 15 years. All suffer from a deformity called lumbosacral transitional vertebrae.

Vucetich and his predecessor, retired professor Rolf Peterson, have called on the National Park Service to take the unusual step of bringing new wolves to the island to attempt to revive the current population through fresh genetics — a so-called genetic rescue.

The park service announced in April it needed more time to study the issue and would not immediately intervene.

Isle Royale officials hope to hear in the next few weeks whether the National Park Service has approved their request for funding to study and complete a management plan of the island's wildlife and vegetation. Spokeswoman Liz Valencia said they hope to start that process in 2015.

"We need to look at the entire ecosystem and how things could change in the future," she said. "How will we manage moose in the future? How will vegetation change?"

Isle Royale Superintendent Phyllis Green did not return a call for comment this week. However, in a statement released last April, she said the park service did not want to rush a decision on how to proceed.

"The plight of these nine wolves is a compelling story," she said in the statement. "But we are charged with a larger stewardship picture that considers all factors, including prey species, habitat and climate change, which could, in a few generations, alter the food base that supports wildlife as we know it on Isle Royale."

Other scientists have also criticized the idea for a genetic rescue because neither wolves nor moose are native to Isle Royale. Neither arrived to the island until the 20th century.

However, Vucetich said time is already running out. Both animals have become part of the ecosystem, whether they were native to the island or not, he said.

Wolves used to kill moose at a rate of 12 percent to 13 percent every year. In the past three years, that rate has dropped below 3 percent, he said. The moose population has doubled in three years as the wolves have declined. More than 1,000 moose now live on Isle Royale.

Without a viable predator on the island, he said, the moose population will grow unchecked and eat away at the forest.

"What's important is the ecosystem function of the wolves," Vucetich said. "If we let Isle Royale proceed too much longer without predation operating normally, it will cause long-term damage to the forest that won't be undone."

Though last winter's cold snap led to near-record ice cover on Lake Superior, researchers don't yet know if any mainland wolves took advantage of the frozen highway to come to the island.

Vucetich said they will collect fecal samples over the winter to test for new DNA. Researchers will also likely notice other changes on the island by then if a new wolf has arrived.

"If there is an immigrant wolf, there would be something different about their relationships and behavior," he said.

One wolf took advantage of the ice bridge to get off the island last year, though she didn't make it far. A radio-collared female named Isabelle crossed the ice but was shot and killed on the mainland.

There was some potential good news this summer, Vucetich said. Three pups born in 2013 appear to have survived their first year.

DNA analysis collected over the winter revealed just a couple of weeks ago that one of the pups was male.

That makes future reproduction possible, though perhaps not likely. All the wolves on the island are closely related, which limits the young male's future mating choices.

"If wolves don't reproduce this year and their predation numbers are lower than last time, it's just going to tell us what we already knew," Vucetich said. "The ecosystem function of wolves was lost three years ago, and we're now in a fourth year. Our concerns are not that we're going to lose it in the future. It's already gone."

Did you know?

Isle Royale is one of the least-visited of all the national parks. Roughly 17,000 people visit the island every year. Yellowstone National Park, by comparison, can see that many people in a single day during the peak season.

However, people stay longer at Isle Royale than nearly every other national park. The average stay at the park is four days.

Did you know?

Isle Royale is home to the Wolf-Moose Project, a 55-year study by researchers at Michigan Technological University. It's the longest-running study of its kind and could only happen at Isle Royale. The island is the only place in the world where major predator and a major ungulate — a term for things like deer, elk and moose — live together without the interference of some other species.