Are the Apostle Islands a refugia for a recently re-colonized forest carnivore? American martens on the Apostle Islands

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Rapid environmental change is reshaping ecosystems and driving species loss globally. Carnivore populations have declined and retracted rapidly and have been the target of numerous translocation projects.

Identifying refuges, locations that are resistant to environmental change, should improve population recovery and persistence. American martens (Martes americana) were extirpated across much of the Great Lakes region by the 1930s and, despite multiple translocations beginning in the 1950s, martens remain of regional conservation concern.

Surprisingly, martens were rediscovered in 2014 on the Apostle Islands of Lake Superior after a putative absence of >40 years. To identify the source of martens to the islands and understand connectivity to the mainland, we collected genetic data on martens from the archipelago and from all regional reintroduction sites.

In total, we genotyped 483 individual martens, 43 of which inhabited the Apostle Islands. Martens on the Apostle Islands were abundant (densities 0.42-1.46/km2) and genetically like mainland sub-populations. We detected some regional gene flow, but in an unexpected direction: individuals moving from the islands to the mainland. Our findings suggest that the Apostle Islands were naturally recolonized by progeny of translocated individuals and now act as a source back to the reintroduction sites on the mainland.

We propose that the Apostle Islands, given its protection from disturbance, complex forest structure, reduced carnivore competition, and maintenance of historical snowpack conditions make this region a potential refugia for a forest carnivore.

Presenter biography

Matt Smith, Department of Forest and Wildlife Ecology, UW Madison

Matt Smith

Matt Smith is a graduate research assistant in the Pauli lab at the University of Wisconsin where his dissertation research focuses on understanding the ecology of martens on the Apostle Islands.

Broadly, he is interested in understanding how environmental change impacts population dynamics, genetics, and connectivity, in addition to, understanding the role biotic interactions play in species persistence.

His current project on the Apostle Islands has reconstructed the colonization history of martens to the islands and future work will address population viability and how marten diet is shaped by competitive interactions. He employs a variety of techniques but has focused on applying noninvasive genetic methods to address questions in conservation biology.

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