Climate Confidential
Overview
Nine wolves, two men, and a drive to upend the conventions of wilderness
protection to save an isolated group of nature’s most elusive
predators. As we explore the themes of limits and borders this month, we
talk to two wolf ecologists who study the ways that isolation can
both sustain and limit a predator-prey ecosystem.
Published December 20, 2014
BY MARY CATHERINE O’CONNOR
Isle Royale rises from the icy waters of Lake Superior about 20 miles south of Ontario, Canada. This far north, temperatures often drop below 15 degrees Fahrenheit during winter. Since the late 1940s, gray wolves have carved out a niche on this narrow strip of protected wilderness, feeding mostly on moose.
The Isle Royale wolf population tends to fluctuate as moose numbers rise and fall. But the most recent count, last winter, found only nine wolves surviving on the island — close to an all-time low — and scientists say they saw no evidence of successful breeding this summer. At its peak, Isle Royale supported a population of at least 50 wolves. Moose, meanwhile, have doubled their numbers to 970 individuals in just three years.
Working the Island
Each winter, Peterson climbs into a small seaplane in Ely, Minnesota, with Vucetich, who joined the wolf-moose research project in the early 1990s. Pilot Don Glaser flies the two scientists to the island, which is also a national park. For two months, the three men live in a small lodge and spend many days in flight, chasing the radio signal from a collared wolf that can lead them to sites where wolves and moose interact.
In the summer, Peterson and Vucetich head to opposite ends of the island to study its diverse plants and mammals, including snowshoe hares and beavers. When they find a moose or wolf carcass, they perform a necropsy to discern the cause of death. But mostly, Peterson and Vucetich observe and document life among some of nature’s most elusive large carnivores.
“We spend an incredible amount of time just getting into position to get a few seconds of observation,” Peterson said. “The number of hours during any year that we actually spend watching wolves, you can count those on one hand.”
In the late 1950s and early 1960s, wolves could cross between Isle Royale and Canada by way of seasonal ice bridges, which formed during three out of the first four winters of the Michigan Tech study. But rising temperatures have made ice bridges increasingly rare. In the past two decades, only three winters have been cold enough for ice bridges to form. And only one of those seasonal links, in 1997, brought a new wolf to the island: a grizzled male that Peterson and Vucetich call the Old Grey Guy.
The Old Grey Guy may have saved the Isle Royale wolves from extinction. By the time he arrived, the island population had dropped to around 24 individuals and every wolf skeleton the researchers examined showed deformities in the spine. The population had fallen to 14 wolves by the time the first of Old Grey Guy’s progeny were born. But even a team of leading geneticists couldn’t pinpoint the root of the problem.
“We didn’t know what the problem was at that time,” Peterson said. But more wolf pups began to survive after the Old Grey Guy came into the picture, and Peterson’s team was able to prove that the population had been suffering from genetic depression. Simply put, without newcomers like the Old Grey Guy arriving from the mainland, the wolves of Isle Royale face a limited selection of mates, and they become inbred.
The Case for New Blood
The Old Grey Guy was the last wolf to migrate to Isle Royale from the outside world. If wolves are to persist on Isle Royale, Peterson and Vucetich say a genetic rescue will be necessary. In other words, they want to bring fresh DNA to the breeding mix by importing wolves from mainland populations.
• • •
Other scientists oppose the idea of meddling with a population that offers such a unique opportunity to observe and analyze trends in a natural laboratory over the long term. “The best thing we can do, for scientific purposes, is to just watch the situation,” former Isle Royale wolf ecologist Dave Mech told me in an interview for Al Jazeera America last spring. He’s concerned that monkeying with the wolf population would taint the scientific record, which has thus far been based only on observing the species.
For now, the National Park Service is taking a wait-and-see approach. In April, Isle Royale superintendent Phyllis Green announced that the park service would be taking no actions in the near term to perform genetic rescue and that it would instead conduct a three-year environmental impact study to ascertain not only the impacts of climate change on the island’s wolves, but also its entire ecosystem. The study was supposed to begin this fall, but a lack of funding meant the study will not commence until 2015 at the earliest.
When Science and Advocacy Meet
When asked if he considers himself an advocate, Peterson says “We’re advocates for science and education, for sure.” What about for wolves? “Through science and education, yes. There are sometimes abusive decisions made — abusive to the conservation of wildlife. And it’s important to study those issues carefully and, where appropriate, make noise about them.”
Vucetich, however, is undeterred. He said controversy like this comes with the job. “I think there might be some self-selection early on among wolf ecologists, figuring out what their tolerance is in getting engaged [in social or policy issues].”
source
No comments:
Post a Comment