Efforts to restore populations of the rare American marten after their disappearance from much of northern New England in the mid-1900s have had limited success. Despite several reintroduction attempts beginning in the 1980s, their distribution remains patchy, especially in Vermont, where they are only known to inhabit the Northeast Kingdom and an area in the vicinity of the Glastenbury Wilderness Area northeast of Bennington.
Several studies by a former graduate student at the University of Vermont have concluded that the best bet for rebuilding marten populations is to ensure that corridors of high-quality habitat are available to allow martens to disperse and reduce inbreeding threats.
Cody Aylward, who is now a doctoral student at the University of California at Davis, described martens as a snow-dependent species residing in thick forests and avoiding developed areas. “If you’re somewhere where martens occur, you’re way out in the wilderness,” he said. “They once were widespread, but after historic habitat losses, they’re just left in these really deep woods.”
Focusing on the small number of martens in southern Vermont, Aylward compared their genetic diversity to those of animals living in the Adirondacks, northern New Hampshire, and Maine. He found the animals from southern Vermont have low genetic diversity, the result of continuous isolation from martens elsewhere in the region.
“The only way to combat the threat of low genetic diversity is to facilitate the exchange of individuals between patches of populations,” Aylward said. “That’s also helpful in case something goes horribly wrong, such as all of the animals from one patch don’t make it through the winter. If they’re connected to other areas, maybe those areas can be recolonized.”
Aylward examined the availability of the animal’s preferred habitat – thick forest, especially at high elevations – and mapped out potential travel corridors between population patches. Because many of these corridors were indirect and quite lengthy, he also mapped corridors that were more direct routes but featured lesser quality habitat.
“One model said the longer, high-quality route is best, and the other said the more direct intermediate-quality route is best,” he said. “It’s hard to argue against targeting the best-quality habitat, but there’s a concern that the animals might not be able to navigate that distance, even though they can disperse quite far.”
On the other hand, the animals are cryptic and difficult to observe, so it’s possible that unknown marten populations persist between the known patches.
“There’s still so much that we don’t know about martens and where they are,” Aylward said. “There may be areas where they’ve existed for decades, and we just didn’t know about them. Whenever I see folks in the community posting pictures of where they’ve seen them, I’m excited because that adds another record in the books. It’s important that people are on the lookout for them.”