Imported wolves settle in as Lake Superior island teems with moose

Thirteen new radio-collared wolves are now scouting Isle Royale in Michigan and feasting on moose, whose numbers this winter reached 2060—the second highest estimate since ecologists began to study predators and prey on the island in 1958. The new wolves, imported to help restore the U.S. national park from overbrowsing by moose, are largely avoiding the territory of the remaining two wolves of the original population.

Twenty female moose are also sporting radio collars, allowing biologists to watch both wolf and moose movements online. After 8 years essentially unfettered by predation because wolf numbers were so low, the moose population has been booming at 19% a year, according to data released today by Michigan Technological University (MTU) in Houghton.

The new wolves are expected to check moose numbers and help restore balsam fir and other plants, according to National Park Service (NPS) planners. And the flood of GPS data is revealing “stuff we’ve never seen before,” says MTU wildlife ecologist Rolf Peterson, such as where moose congregate to feed on new spring growth. Peterson and his colleagues plan to chemically analyze the specific balsam fir trees moose eat to determine whether they choose twigs with compounds that may have anti-inflammatory properties.

Meanwhile, the collared wolves are transmitting numerous locations where they cluster, presumed to be moose kills, which will help researchers collect moose bones. These new data “will totally redirect our attention,” Peterson says.

Moose in the Great Lakes region are at the southernmost edge of their range, and they are declining as the climate changes—except on Isle Royale, notes Adrian Wydeven, a wildlife biologist retired from the Wisconsin Department of Natural Resources in Cable. The new data may help scientists understand what’s behind that difference, he says. He sees the project “as more of a moose conservation effort rather than wolf conservation.”

The NPS wolf relocation had a rough start, including a partial U.S. government shutdown in January, bad weather, and depleted funding. Two wolves died, one before transport, one after several weeks on the island; one imported female traveled back home when an ice bridge to the mainland formed in January.

Eight wolves hail from Michipicoten Island Provincial Park in Canada across Lake Superior. (The others are from Minnesota and mainland Ontario in Canada.) Wolves on the smaller Ontario island had eliminated their chief prey, caribou, and had been subsisting mainly on beaver. These wolves appeared underfed, but they were relocated as a pack, boosting their chances of thriving on Isle Royale, Peterson says.

Meanwhile, the island-born, highly inbred pair of the original population “is not giving up on each other,” says Peterson, who observed them from a spotter plane in February. As in previous mating seasons, the now 8-year-old female rebuffed the interest of the 10-year-old male, her father and half-sibling. They kept busy scent marking their territory in response to the relocated wolves as well as to tracks of other mainland wolves that apparently found their way across the ice bridge and back.

The pair’s pedigree demonstrates the challenge of maintaining genetic diversity on Guam-size Isle Royale. “Inbreeding is basically inevitable due to the island’s small size,” says University of California, San Francisco, geneticist Jacqueline Robinson, who analyzed the genomes of 11 Isle Royale wolves from blood samples collected since 1988. To further diversify the population, NPS plans to import more wolves from Michigan this fall.