The last two wolves on Isle Royale are hanging on against the odds even as scientists and administrators in the National Park Service decide how and when to bring more wolves to the island to rebuild the pack.
Researchers at Michigan Technological University on Monday released the results of their 59th annual winter survey of wolves and moose on the island that found the last two wolves still alive.
The wolf numbers have crashed from 24 in 2009 to just the pair — a seven-year-old female and nine-year-old male — as inbreeding spurred genetic defects that have crippled the wolves’ ability to survive and reproduce.
The wolf pair are believed to be too old to reproduce on their own. But even if they could, it probably wouldn’t help. Their genetic plight is underscored by the fact they are not only father and daughter but also half-siblings who share the same mother. The pair mated and had a pup in 2015, researchers said, but it was visibly deformed and didn’t survive to the 2016 winter survey.
As wolf numbers have declined for nearly a decade, moose numbers on the Lake Superior island have skyrocketed, from 1,300 last year to 1,600 this winter. John Vucetich, Michigan Tech wildlife researcher, said the moose population could double to record high levels within three or four years.
The research shows the moose population increasing by nearly 22 percent annually. Vucetich and fellow Michigan Tech researcher Rolf Peterson, who has been studying the island’s wildlife for six decades, said moose numbers are going up so fast because of high reproduction rates, virtually no pressure from wolves, mild winters and an abundance of food.
But the expanding moose herd is bad news for the island’s forests as moose begin to eat too much, damaging the forest’s ability to regenerate. Eventually moose will run out of food, and their population will crash, too.
“Everything we’re seeing on Isle Royale is consistent with our past understanding of the ecosystem’s dynamics,” Vucetich said in releasing the new report. “We have every reason to expect the moose population will continue to grow and increasingly impact the forest.”
It’s because of that unhealthy predator-prey balance that the National Park Service decided in December to intervene and bring new wolves to the island. Isle Royale officials now are deciding how many wolves to bring, where to get them and when to bring them to the island, with a decision expected this fall.
In addition to the Park Service’s “draft preferred alternative” of introducing up to 30 wolves immediately to bolster the population, the Park Service considered a no-action alternative and a slower reintroduction, starting with just six to 15 wolves and waiting to see what happened.
Phyllis Green, Isle Royale park superintendent, said the wolf reintroduction proposal attracted more than 5,000 comments from the public. Her staff currently is poring over those comments, with a final decision expected by fall.
“We’re seeing the full spectrum of responses. A significant number are from wilderness supporters who don’t want us to do anything,” Green told the News Tribune on Monday. “And there is support for (wolf reintroduction) as quickly as possible.”
Green said it probably would be 2018 before any new wolves are brought to the island, if the draft is adopted as a final decision. Any relocation likely would occur in late fall or early winter, she said.
The 45-mile-long, 143,000-acre island is located about 15 miles off Minnesota’s North Shore.
Moose came to the island around 1900, peaking at 2,445 in 1995 and hitting bottom at just 385 in 2007. Wolves are relatively new to the island, having crossed the ice in 1949. Their numbers reached a high of 50 in 1980, and 24 wolves roamed the island as recently as 2009.
Climate change, spurring fewer years of ice bridges between the island and the mainland, has reduced the number of new wolves venturing to the island and reduced the pack’s genetic diversity.
Researchers also have found that, due to the diminishing wolf pack, the number of beaver colonies on the island has dramatically increased, from about 100 to about 300 in just six years.
The 59-year Michigan Tech effort is the longest running predator-prey study in the world.