Wolves on a remote island in Lake Superior are flourishing, but their growing numbers are taking a significant toll on the moose population, their primary food source, according to a report published this week. This delicate ecological balance is under scrutiny in a unique natural laboratory.
Isle Royale: A Natural Laboratory
Isle Royale, a vast 134,000-acre (54,200-hectare) national park situated in the far western reaches of Lake Superior, between Grand Marais, Minnesota, and Thunder Bay, Canada, serves as an unparalleled site for scientific observation. Here, researchers can study wolf and moose dynamics largely unhindered by human interference.
Population surveys of these iconic species have been conducted on the island since 1958, traditionally an annual winter undertaking when the roadless park is closed to visitors. These long-running studies provide invaluable data, yet recent years have presented significant hurdles for the dedicated research teams.
Survey Challenges Overcome
The 2021 pandemic forced the cancellation of the survey for the first time in its history. More recently, researchers were ordered to evacuate during their 2024 winter survey after weeks of unseasonably warm weather rendered the surrounding ice unsafe for ski-plane landings. These planes are crucial for easier wildlife tracking, as the island lacks a runway, necessitating landings on the iced-over Lake Superior. Last year proved equally challenging, with the entire effort abandoned after a pilot experienced a last-minute medical emergency.
But this year, a team of researchers led by scientists from Michigan Tech University were able to conduct a survey from 22 January through 3 March. Findings from the survey led them to estimate the island's wolf population at 37 animals. Data scientists gathered before they evacuated in 2024, a survey showed the population was 30. The 2026 estimates are the highest since the late 1970s and represent a marked improvement since the population dwindled to just two wolves a decade ago. Researchers believe inbreeding led to depressed survival rates in pups.
Moose Population in Sharp Decline
The island's moose population, though, is declining dramatically. This year's survey put the population at 524 moose, down 75 per cent from a high of 2,000 in 2019. Wolves likely killed almost a quarter of the moose population over the last year, scientists estimated. For the first time in almost 70 years, researchers observed no moose calves during the winter survey. Sarah Hoy, a Michigan Tech researcher who specializes in predator-prey interactions and one of the survey's co-leaders, said scientists had to brave wind chills that dipped to minus 50 degrees Fahrenheit (minus 45.5 Celsius) and it was difficult to keep warm with the woodstoves in their cabins. But clear skies facilitated exceptional observations. The scientists spotted wolves on all but one survey flight, she said.
One of the highlights was watching a pack snuggle up together on the ice on Valentine's Day, she said. “It's always such a privilege to get to see wolves interacting, witnessing courtship behavior, pups playfully tugging on each other's tails, or a pack working together to take down a moose,” she said. Scientists plan to conduct summer research on the island with an eye toward how the burgeoning wolf packs can maintain balance with the rest of the ecosystem.
