Movement corridors reveal conservation opportunities, challenges, and indigenous roles in the recovery of American Martens (Waabizheshi; Martes americana) in the upper Great Lakes region

Abstract

Reintroductions are increasingly occurring in landscapes differing from historical conditions. These novel landscapes often feature unknown connectivity, creating uncertainty around long-term recovery of reintroduced populations. We studied a recovery network of American martens (Waabizheshiwag [Ojibwe], Martes americana) in the Great Lakes region where serial reintroductions have resulted in eight populations with uncertain viabilities. Recent observations suggest dispersal is occurring, although functional connectivity within the network is unknown. To quantify network-wide connectivity and identify corridors, we analyzed >1100 genotyped individuals collected from 2000 to 2023. We hypothesized populations within the recovery network are connected via dispersers, especially from populations in Michigan and Minnesota, and that landscape resistance governs the degree of connectivity. We identified two spatial genetic structures in the network: a cline of relatedness originating in the Upper Peninsula of Michigan and extending into Wisconsin, and a genetically distinct population in Minnesota that were related to the rest of the network's subpopulations via historical translocations. A resistance landscape, parameterized by a resource selection function, revealed connectivity is governed by forest complexity across the Great Lakes recovery network. Notably, anthropogenic fragmentation as well as natural ecoregions elevated resistance and reduced connectivity. These ecoregions feature unique conservation concerns and sometimes conflicting management objectives—further complicating regional species recovery. Key corridors were protected with notable Tribal jurisdiction (Bad River Band of Lake Superior Ojibwe). However, we also identified important gaps in corridor protection within Minnesota. Collectively, these areas represent important opportunities for tribal engagement and land management to facilitate natural dispersal within a recovery network.