The wolf population on Isle Royale is "most certainly headed for extinction."
That's the prognosis from researchers at Michigan Technological University, which put out its annual look at how the wolves (and moose) on the island are doing.
Isle Royale is located in Lake Superior, about 15 miles from the very northeast tip of Minnesota, up by Grand Portage. In the 1940s, wolves crossed an ice bridge from mainland Ontario on to the island, establishing their presence there for the first time.
But now the Isle Royale wolf population is on the verge of dying off.
Just 2 wolves left
At the start of 2015, there were three wolves on the island.
That number has likely dropped to two, according to a news release about the newest survey.
The two wolves still on the island are believed to be adults, one male and one female, and both born from the same mother (so half-siblings) – but the male is also believed to be the father of the female. As researchers put it, "any offspring from this pair would be extremely inbred and probably non-viable."
They're between 6 and 8 years old, and for comparison, the university's news release notes the average lifespan for Isle Royale wolves is about 4 years.
During winter surveys, nobody actually saw live wolves, but they did note fresh tracks and hear the howling of, at most, two wolves. There was also no evidence the wolves had reproduced, according to the report.
What happened to the wolves? Inbreeding
The "crash," as the university puts it, is likely the result of that genetic inbreeding, like what's seen in the two current wolf occupants.
Peak population came in about 1980, when it was pegged at about 50 – it very quickly dropped down toward 10, and for awhile fluctuated around 10-20. But since 2009, when researchers counted 24, the population has plummeted.
From 2014 to 2015, six of the nines wolves on the island at the time died – the reason still isn't known, the university's report notes.
Genetic rescue is pretty much a wasted effort at this point, the study says, and if wolves are going to live on Isle Royale, it'll likely have to happen with a re-establishment.
The National Park Service last month said it would stop considering a variety of population management plans, and instead focus on one question: whether to bring wolves to the island in the short-term, and if so, how to best do that.
Why bring wolves back? Because of moose
It would be about balancing the ecosystem.
At the same time wolf numbers have fallen, the moose population has shot up – it's now at about 1,300 and expected to keep increasing, the university's news release says.
That's because wolves acted as a natural population control. Without wolves, the moose numbers will continue to climb – which then impacts the vegetation on Isle Royale, possibly damaging the forestation.
"Concerns remain that the upcoming increase in moose abundance will result in long-term damage to the health of Isle Royale’s vegetative community," the report says.
The Isle Royale work is part of the longest running predator-prey study in the world, the university says. Part of the reason the island was valued is because it was a completely natural laboratory for study, the report says. Humans do not hunt wolves or moose on the land, and do no forest management.
You can keep up with the project at the Isle Royale Wolf website.