On Lake Superior, wolves and their prey are starring in a pair of life-or-death dramas.
On a Canadian island, wolves threaten to wipe out a once-strong herd of caribou -- triggering rescue efforts. Across the lake, on the U.S. side, the decline of a wolf pack has led to a skyrocketing moose population -- and pleas to import more wolves.
In both cases, naturalists are seeking a way to restore the delicate balance between predator and prey. And it isn't easy.
Let's start on Canada's Michipicoten Island. Wolves came to the island across the frozen lake, and began attacking the region's last remaining caribou herd. The number of caribou dropped from more than 450 in 2014 to a few dozen this winter, the Duluth News Tribune reports.
A public outcry followed, and the Canadian government recently staged a daring rescue -- carrying nine caribou via helicopter to the Slate Islands, a distance of about 80 miles.
That will give some of the caribou a reprieve. And the Ontario Ministry of Natural Resources and Forestry hopes they thrive in their new home. But some worry that another big freeze will create an ice bridge to the island, allowing wolves to attack again.
“It’s possible that wolves could make it over to the Slate Islands, and it would only take them a couple of weeks to eat through the caribou,” Leo Lepiano of the Michipicoten First Nation told the New York Times. “It’s kind of foolish to put all your eggs in one basket.”
Meanwhile, U.S. scientists and officials are confronting a similar problem on Isle Royale National Park.
Wolves and moose have lived on that remote island for years. But all but two of the wolves have died off, after being weakened by inbreeding and disease, according to Wolves and Moose of Isle Royale, a scientific study that has been going for almost 60 years.
With fewer predators, the moose population has exploded, to more than 1,600, the Detroit Free Press reports. That's bad for the island's fir trees and other plants, which are being gobbled up. A food shortage could lead eventually to moose deaths.
The National Park Service is nearing the release of its plan for Isle Royale. A draft included three options for bringing wolves to the island. The agency prefers the option to import 20 to 30 wolves over a period of up to five years.
Gordon Eason, a retired biologist who worked for the Ontario ministry, spoke to the Times about Michipicoten Island -- but his words also are fitting for Isle Royale: “I guess that’s one of the costs of managing threatened species or endangered species. You have to intervene in part of the cycle that isn’t functioning anymore.”