On a wild, remote island in Lake Superior called Isle Royale, gray wolves have lived and thrived for more than 60 years. In the forests on this island — which encompasses the majority of Michigan’s Isle Royale National Park — a wolf population that grew to almost 50 individuals once contributed to a biodiverse, healthy ecosystem.
In recent years, however, the number of wolves on Isle Royale has plummeted. In 2009, scientists from the Wolves and Moose of Isle Royale project — begun in 1958 and now the longest continuous study of a predator-prey system in the world — documented only 24 wolves living on the island. As of February 2014, that number had dwindled to nine — the second lowest total for the island ever recorded.
Some blame climate change for the decrease. Others say it is just the natural order of things for species to come and go in a particular area. But whatever the cause, the question for the future health of the island and the park is: should we intervene to save Isle Royale’s wolves?
Reasons to reintroduce
In the late 1940s, three gray wolves from Canada walked 15 miles across the ice of Lake Superior to Isle Royale. The island’s appeal probably had a lot to do with a resident population of moose, thought to be descended from forebears who swum to the island a few decades earlier. In the past, during most winters, the Lake Superior waters between mainland Ontario, Canada, and the island would freeze over, allowing new wolves to find Isle Royale. But beginning in the 1970s, rising temperatures caused ice bridges to form only about once a decade, which means that the chance of new wolves making it to the island to supplement the gene pool steadily decreased. What’s resulted is the most extreme case of inbreeding ever documented in a wolf population.
Some biologists have put forth a proposal to capture a few wolves from the Ontario mainland and release them on Isle Royale in order to augment the gene pool and increase the number of wolves on the island. They believe that the main reason to keep the wolf population going is to preserve the island’s ecosystem. Moose love to browse balsam fir. Unchecked by predators, they could quickly decimate all the balsam fir trees on the island — a change that would cascade down through the food chain. In an average year on Isle Royale, in fact, wolves kill about 10 percent of the moose; but in the last two years, only 2 percent of the moose population has succumbed to predators. As a result, the moose population has doubled in the past three years — to more than 970 — and that’s not good for the island’s biota as a whole.
Sense for standing back
Almost the entire island of Isle Royale is protected under the 1964 Wilderness Act. In the past, most environmentalists have taken a hands-off approach to such wild lands. The rationale is that the natural order on Earth is that species will continually “wink in” and “wink out”; human manipulation of species’ numbers in a landscape can be a slippery slope. In 1900, caribou and lynx were the largest animals on the 206-square-mile Isle Royale. Both eventually disappeared, along with smaller species, such as coyotes and spruce grouse. Wolves and moose are relative newcomers here, along with tricolored bats and tree frogs. So, unlike in Yellowstone National Park, wolves aren’t native to Isle Royale. Therefore, performing a genetic rescue by introducing new wolves would break new ground.
What’s more, point out those against introducing new wolves to Isle Royale, the global trend of climate change has brought with it unpredictable extremes, such as more severe storms. It’s possible that longer-lasting ice bridges between the mainland and the island are in the near future.
On April 9, 2014, the U.S. National Park Service issued a statement regarding the Isle Royale wolves: “The agency will not take any immediate action to bring wolves to the island.”
Leaving the door open
In November 2013, a report on climate change released by the park forecasted that wolves and moose might not survive on the island in the coming years as the temperature warms — despite more severe storms and the longer-lasting ice bridge theory. That saddens those who wish to or have visited the island; Isle Royale’s wolves have drawn many tourists to Michigan. Places untouched by humans and where wolves roam free are rare on the planet.
The National Park Service did leave one ray of hope for those who want to see Isle Royale’s wolves endure. In its April 9 statement, the agency added that if the island’s population of wolves declined to all males or all females, and if the moose population grows to overbrowse island vegetation, bringing more wolves in remains an option.
What’s not clear is whether these new wolves would still find brethren there, or whether they would be starting a brand-new race.
Do you think biologists should step in to save the Isle Royale wolves? Or should we allow unaltered nature to take its course?
Feature photo: Wolves were native to Yellowstone National Park. After being extirpated in the mid 1900s, they were reintroduced in 1994. ©Eric Rock