Isle Royale National Park's Wolf Population Down To Just Eight, No New Pups Last Year
Just eight wolves can be found at Isle Royale National Park, the lowest count ever tallied, and no new pups were brought into the population last year, another first that seemingly moves the population closer to extinction.
But against that dire news, National Park Service officials continue to work towards a solution that could reverse the wolves' plight, and a rebounding moose population could contribute by offering the eight a bountiful prey base.
If there's any good news to be found in the annual census released Tuesday, it's that biologists now believe at least four, and maybe five, of the wolves are females; a year ago they thought there were just two.
Tracking the vagaries of wolf dynamics at Isle Royale is difficult, wildlife biologist John Vucetich explained Tuesday, because genetic sampling is used to determine sex, and those tests take time. Lack of funds prevented testing on scat samples collected the past two years until this past January, when the results became known.
Rebuilding the island's wolf population won't be easy, though, as the animals long have suffered from inbreeding.
Three decades ago Isle Royale was home to multiple packs totaling 50 individuals. But lone wolves searching for new territories don't easily find themselves on Isle Royale, as ice bridges that allow them to cross Lake Superior from Ontario to the island are few and fragile due to warming waters and somewhat mild winters. As a result, there hasn't been a refreshing infusion of off-island wolf genes since a Canadian male made that 15-mile ice bridge crossing in 1997.
His arrival did provide a welcome burst of genes. He sired 34 offspring, which in turn produced at least 22 of their own. But the passage of time without additional mainland interlopers has narrowed the gene pool.
Park officials are expected to propose possible solutions later this year. In the meantime, wildlife biologists will be carefully watching to see if any pups are born this spring. Last year's failure to produce a litter was startling.
"For wolves, making pups is a relatively easy thing to do," Dr. Vucetich, who monitors the wolves along with Dr. Rolf Peterson from their Michigan Tech base in Houghton, Michigan, said Tuesday during a phone call. "When they are unable to do it, it certainly is noteworthy."
Adding concern to that failure a year ago was the new realization that there were at least four females for breeding a year ago, said Dr. Vucetich. "What's of a concern now, is that the reason they're not reproducing is not because they can't find females; it's for some other reason," he said.
And yet, that concern could vanish overnight if pups show up next month.
"If they have pups this April, then I guess you'd say (last year's failure) is a fluke, they just couldn't do it," the wildlife biologist said. "But if they don't reproduce two years in a row, then of course, it's already an OK question to ask: Is this the beginning of the end?"
Moose, Vegetation Thriving As Wolves Decline
The steady decline of wolves at Isle Royale comes as other facets of the park's natural kingdom are on the rise.
While the moose population plummeted to as few as 530 in 2009, that decline allowed robust vegetative growth to occur on the 45-mile-long island in Lake Superior. That growth fed a rebound, and today the ungulates number roughly 900.
"Because moose were so low for so long, it gave an opportunity for the vegetation to just rebound in a way that I'd never seen in my time on Isle Royale," Dr. Vucetich said. "Balsam fir has experienced a release of growth that they have not seen in 100 years. Moose are up to their eyeballs in food."
And that bountiful buffet has led to an abundance of moose calves, noted Isle Royale Superintendent Phyllis Green.
It remains to be seen if the burgeoning prey base will be enough to buoy the wolf population. Understanding that, the park superintendent has been working with experts in and out of the Park Service to explore options for giving the wolves a lift.
Those options range from doing nothing and possibly watching the predators vanish from the island to bringing in some new animals to perform a "genetic rescue" by contributing to the currently shallow gene pool.
"Some people say, 'Why don't you just go out there and throw wolves at the problem?'" she said Tuesday during a call from her office. "Well, wolves kill wolves. They have territorial disputes all the time. So if your intent in doing that was to replenish the genetics that are there, that might not be your end result.
"Whatever action we take has to be extermely well-thought out. We've gained a lot from the research that's been done for the last 50 years, I think. We need to sort out what are the critical things we need to learn in the next 50 years, too."
For now the eight wolves are roaming the island in two packs of three -- the remnants of the old Chippewa Harbor Pack at the east end and the so-called "West-end Trio -- and two lone wolves in between.
While Superintendent Green expects to have a draft proposal for how to manage the wolves for public review in a few months, she noted Tuesday that climate change is bringing a lot of changes to the park and affecting a lot of species. All that information, plus genetic projections, must be considered in looking at the wolves' future.
"We know these wolves are having genetic issues. Other populations that get isolated because of climate change will, too. So there's going to be limited resources to address all of the issues that come out of climate change," she said. "We have to be really smart about where we focus our resources. That's part of this. That's why we need a good discussion internally on policy and wildlife management and intervention vs. non-intervention. The wolves, they're certainly tenuous, but we've got time to be thoughtful."