NECEC and Forest Fragmentation Part 3: The American Marten

We’re continuing our series on Central Maine Power’s proposed New England Clean Energy Connect (NECEC) transmission line project, focusing on its impacts to Maine wildlife. Maine Audubon feels strongly that NECEC and its mitigation plan offer unsatisfactory protections for Maine wildlife and is especially deficient in its consideration of habitat fragmentation.

We began with an introduction to NECEC and forest fragmentation and continued with a look at the impacts to ground-nesting birds like the Ovenbird.

In considering the impacts of NECEC and habitat fragmentation on Maine wildlife we will now consider a species that requires large unfragmented mature forest habitat, the American Marten.

Martens are large weasels that doggedly and energetically pursue a variety of prey through the deep woods. American Martens — also known a=s the Pine Marten — have a sleek body and a cute, catlike face…cute unless you’re on the receiving end of some sharp teeth, of course.  Active year-round, they hunt just about any prey they can tackle, including Snowshoe Hare, voles, mice, birds, fish, and insects. American Marten range across Canada and the Rocky Mountains, but only dip into the eastern United States in northern Maine and New Hampshire. They have large home ranges – up to 2,200 acres – and must travel extensively to find the food, water, denning sites, and resting places they need.

Snowshoe Hare are an important prey item for American Marten. Photo: Kent McFarland / Flickr

Although Martens have a varied diet they are rather particular about their habitat. Studies have shown that Martens are very rarely found in areas with low forest cover, even where forest connectivity remains. (Christina D. Hargis  John. A. Bissonette David L. Turner. The influence of forest fragmentation and landscape pattern on American martens. Journal of Applied Ecology, 25 December 2001. https://doi.org/10.1046/j.1365-2664.1999.00377.x.) The study found that Martens avoid clearcuts and other large openings. Additional studies at the University of Maine have found that marten prefer older, more structurally complex forests, with at least 60% canopy closure, and lots of dead standing and down wood for traveling through the forest and finding their prey.

Habitat preferences of marten are shared by over 70% of all vertebrate species in Maine as well, so conserving habitat that’s good for marten is also good for many other species. Recent changes in forest harvesting have dramatically reduced suitable habitat for marten and many other species that prefer mature forest characteristics, and as a result, their populations have been declining.  While low levels of fragmentation may not harm Marten much where connectivity remains, a permanent transmission corridor like NECEC may have the effect of creating a partial or full barrier between different patches of  Marten habitat and ultimately cause further population declines.