The closely watched wolf population on Isle Royale National Park has dropped to just three — the lowest number recorded since scientists began tracking them more than 50 years ago and a sign that without human intervention, they will likely soon vanish from the island altogether.
In their annual wolf survey released Friday, researchers from Michigan Technological University said the number has plummeted from the nine they saw last winter, continuing a decline in a population that once numbered as high as 50.
Moose, however, are thriving. There are now about 1,250 on the island, a number that's increasing by about 22 percent a year. At that rate, the scientists said, their population will double in three years, a sharp contrast to the dwindling numbers a few miles away on the mainland in northern Minnesota.
The tiny number of wolves answers at least one question in the ongoing debate about whether humans should interfere in what has been a 57-year natural drama of predator and prey on Isle Royale. It's now too late for "genetic rescue" by adding one or two wolves to the island in the hope that they would breed with others and add badly needed genetic diversity to the inbred group, and perhaps more offspring.
The three wolves consist of two adults, likely a breeding pair, and a 9-month-old pup that could be theirs.
The youngster has some evident genetic deformities, making its survival unlikely, they said.
If the adults are a breeding pair, they are unlikely to mate with another wolf.
They appear to be in good shape and capable of having more pups, said Rolf Peterson, one of the researchers who's been studying the predator-prey dynamic for several decades.
But they are now middle-aged and nearing the end of their reproductive lives, he said.
"You don't have the sense there is much time left," he said. Now, the only other option to maintain the balance would be to bring a whole new pack to the island.
Peterson and co-researcher John Vucetich have argued vehemently in favor of adding wolves to the island before the ecosystem crashes from an exploding moose population. The National Park Service is considering its options.
It is developing a new management plan for the island, also a wilderness area, that could take months or even years to complete.
Isle Royale National Park Superintendent Phyllis Green said the plan has to consider not just wolves and moose, but the entire island and the changing climate. The latest report does not change the direction or the timing, she said Friday.
"I think there are many more questions raised as a result of these winter events that will be looked at as part of the planning process," she said.
The question has been further complicated by the formation of ice bridges between the mainland and the island in the last two years, adding some unexpected drama.
Last year, a lone female wolf named Isabelle left the island as soon as the bridge formed, most likely seeking a mate. But she was shot with a pellet gun on the Grand Portage Indian Reservation by someone trying to chase her away from a dog. Instead of scaring her off, however, the pellet slipped between her ribs and killed her.
This year two wolves from the mainland — one with a tracking collar from Grand Portage band researchers — wandered over to the island.
Vucetich, who saw them curled up in the snow while on a regular aerial survey, said they did not interact with the wolves on the island. Within a week they were gone.
"Everyone wants to know: What does this mean?" Vucetich said.
The visiting wolves raise hopes for saving the population, he said, but it's not certain that anything would have happened even if the two groups had encountered each other.
But David Mech, a wolf biologist with the U.S. Geological Survey, said the ice bridges mean it's not necessarily over for the wolves of Isle Royale. He's long advocated that the park service and scientists should let nature take its course, and that wolves are remarkably resilient.
"Let's see what happens," he said. "Maybe we go back to where we were 60 years ago when the population just started. Maybe it will start up again."
Staff writer Tony Kennedy contributed to this report.
Josephine Marcotty • 612-673-7394
