Wolves on Isle Royale are rebounding to levels unseen in nearly fifty years, but the predators are rapidly depleting the moose herds that sustain them, according to researchers who completed their first full wildlife survey of the remote Lake Superior island in three years.
A team led by Michigan Tech University estimated the wolf population at 37 animals following a survey conducted from January through early March. That represents a sharp jump from 30 wolves counted in 2024 and marks the highest total since the late 1970s. The recovery comes after the population crashed to just two wolves a decade ago, a bottleneck researchers attributed to inbreeding that depressed survival rates among pups.
The moose story tells a darker arc. This year's count found only 524 moose on the 134,000-acre national park, a stunning 75 percent decline from the 2,000 animals recorded in 2019. Researchers estimate wolves killed nearly a quarter of the remaining moose population over the past year alone. Most jarring: the winter survey found zero moose calves, a development researchers said was virtually unprecedented in their seven decades of monitoring the island.
Isle Royale, nestled in far western Lake Superior between Minnesota and Canada, has long served as a natural laboratory for predator-prey dynamics. The roadless island's isolation offers scientists rare insight into how these animals interact without human interference. But conducting research there requires ski-plane landings on frozen lake ice, a logistical challenge that nearly sidelined recent work entirely.
The pandemic forced cancellation of the 2021 survey. In 2024, warm weather made lake conditions unsafe for landing, and researchers were ordered to evacuate. Last winter's effort collapsed when the pilot suffered a medical emergency. This year's successful campaign came after teams braved wind chills approaching minus 50 Fahrenheit and struggled to stay warm in wood-stove heated cabins.
The conditions produced exceptional observations. Sarah Hoy, a Michigan Tech researcher who co-led the effort, said scientists spotted wolves on all but one survey flight. Clear skies allowed researchers to witness courtship behavior, pups playing, and hunting sequences as packs brought down moose on the island's frozen surfaces.
"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," Hoy said.
The dramatic shift raises fundamental questions about ecosystem balance. Researchers now plan summer fieldwork aimed at understanding how the expanding wolf population can coexist with a moose herd that appears headed toward crisis without intervention.
Author James Rodriguez: "The wolf recovery is a genuine conservation win, but these numbers show predator and prey can spiral out of sync fast, and winter counts only tell part of the story."
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