After decades of trapping, the last known American marten was spotted on Isle Royale in 1917. Fifty years later, in 1966, the National Park Service planned to reintroduce martens to the national park situated in Lake Superior, but nobody knows if the agency ever followed through. Then, in 1993, martens were confirmed on the island for the first time in 76 years.
Whether these small, forest-dwelling carnivores — valued historically for their fur — had been hiding there the whole time, found their way back, or were introduced in the 1960s without any records has remained a mystery for the last quarter century.
But in new research published today (Aug. 23, 2018) in the journal Scientific Reports, University of Wisconsin–Madison researchers in the Department of Forest and Wildlife Ecology, collaborating with the National Park Service, traced the recolonization to martens likely arriving in the 1990s, shortly before they were spotted.
Genetic studies of martens from Isle Royale and nearby populations in America and Canada showed that the contemporary population came from nearby Ontario, Canada. The animals likely wandered over on an ice bridge in the winter, the researchers speculate.
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Image via Jonathan Pauli, University of Wisconsin