Assessing the success of American marten reintroduction to northern Wisconsin


The American marten (Martes americana) was extirpated from Wisconsin in the early 20th century, and they are currently the most endangered mammal in Wisconsin. Following multiple reintroduction attempts over the last 4 decades, there are recovering populations of martens in both the Chequamegon National Forest (CNF) and the Nicolet National Forest (NNF). To assess the potential role of competition in the delayed recovery of martens to the CNF, we used occupancy models and stable isotope analysis to explore niche partitioning between martens and a primary competitor, the fisher (Pekania pennanti). We observed significant niche overlap between the two species and concluded that competition may be contributing to the delayed recovery of martens in the CNF. Concurrently, we also non-invasively sampled marten DNA from the CNF and used genetic mark-recapture and parentage analyses to estimate marten abundance, density, survivorship, and recruitment. Many of these population processes and attributes were previously unknown for CNF martens and sound estimates of these parameters have helped gauge reintroduction success and guided future management.

To compare these vital rates and gain an understanding of mechanisms limiting marten recovery, we have also initiated a project in the NNF where recent track surveys and anecdotal evidence suggest a potentially stable population. Specifically, we are continuing to use genetic mark-recapture techniques along with prey assemblage estimates to assess factors such as immigration and nutritional limitation. Determination of vital rates will allow us to perform a population viability analysis, model the effects of various management strategies, and ultimately assess viability of martens in Wisconsin.

This work is funded by the US Department of Agriculture, Great Lakes Indian Fish & Wildlife Commission, US Forest Service, and the Wisconsin DNR.