An on-going study that takes place on Isle Royale, Michigan's only National Park, has found that the wolf population has increased while moose continue their multi-year decline.
The purpose of this study is to understand why the wolf and moose population on Isle Royale fluctuate. It's the longest running predator-prey studies in the world administered by researchers at Michigan Technological University.
"There's now 37 wolves on the island organized into three packs, between about 10 and 12 wolves in each pack," Sarah Hoy, one of the researchers who worked on this study, said.
The study also shows this year's wolf population is the highest its been since the 1970s. Hoy says the moose population has decreased by 75% since 2019, due to more wolves hunting them.
Back in 2019, wolves were reintroduced at the park because some of the wolves were too closely related that they couldn't produce any offspring.
"Since the wolves were reintroduced to Isle Royale, there were 19 wolves brought from different populations in the Lake Superior region," Hoy said. "We've been monitoring how well that newly established wolf population has been doing and it took a couple of years to stabilize, but the population has steadily increased."
She says when there was a lack of wolves at Isle Royale, the moose population increased rapidly.
"It went from about 400 moose to over 2,000 and moose are really large animals. They weigh over 800 pounds, and they eat a lot of food, so a lot of plants, so a moose can eat about 40 pounds of vegetation every day during certain times of the year," Hoy said.
There was also an ice bridge that formed at Isle Royale in recent years due to the bitter weather, connecting the remote archipelago to the mainland.
When the bridge forms, it only lasts one to two days, but this year it lasted two weeks, Hoy said.
"There were kind of reasonable opportunities for wolves to perhaps come across, but we didn't observe any kind of evidence of that," she said. "We did kind of see that wolves were kind of spending time walking along the shoreline."
