Wolves on a remote Lake Superior island appear to be rebounding after years of strain, but researchers say the increase is coming alongside a sharp decline in moose that serve as their primary food source. The findings come from Isle Royale National Park, a 134,000-acre (54,200-hectare) refuge far from roads and human visitors, where scientists conduct long-running predator-prey monitoring.
Researchers used a winter survey window that ran from Jan. 22 through March 3. They estimated the island’s wolf population at 37 animals, compared with 30 wolves based on data gathered before researchers evacuated the island in 2024. The 2026 estimate represents the highest wolf population since the late 1970s, researchers said, and it marks a notable improvement from a period when the population had dwindled to just two wolves about a decade ago.
The survey also comes after multiple disruptions to the annual winter work in recent years. The pandemic in 2021 forced scientists to cancel the survey for the first time, according to the report. Then, during the 2024 winter effort, the National Park Service ordered researchers to evacuate the island after unusually warm weather left the ice surrounding Isle Royale unsafe for ski-plane landings, the report said. The researchers rely on those planes to track wildlife because the island has no runway, and the need to land on iced-over Lake Superior adds risk and complexity.
Plans for 2025 were also derailed, the report said, after a pilot suffered a medical issue late in the trip. This year, a team led by researchers from Michigan Tech University carried out the winter survey and produced the new estimates for both wolves and moose.
Scientists reported that the moose population is declining dramatically even as wolves rebound. This year’s survey estimated 524 moose on Isle Royale, down 75% from a peak of 2,000 in 2019. The report said wolves likely killed almost a quarter of the moose population over the last year, and researchers observed no moose calves during the winter survey for the first time in almost 70 years.
Sarah Hoy, a Michigan Tech researcher who specializes in predator-prey interactions and one of the survey’s co-leaders, described the harsh conditions during the work. She said researchers faced wind chills that dipped to minus 50 degrees Fahrenheit (minus 45.5 Celsius) and that it was difficult to keep warm with the woodstoves in their cabins, even as clear skies improved observation opportunities.
Hoy said the scientists spotted wolves on all but one of the survey flights. She also highlighted moments from the study period, including watching a pack snuggle together on the ice on Valentine’s Day, and she said the team observed behaviors such as courtship, pups tugging on each other’s tails, and packs working together to take down a moose. The researchers said they plan summer research as well, with an eye toward how the growing wolf packs can maintain balance with the broader ecosystem.