Engineering a Comeback

The deep woods of Pennsylvania’s northern tier could be home again to an iconic native mammal not seen in the state in 120 years.

The American marten (Martes americana) — a weasel-like creature as prized for its pelt as its cousin, the mink — was gone from the landscape by about 1900 as a consequence of rampant logging and unregulated trapping.

The Pennsylvania Game Commission is now considering reintroducing the diminutive mustelid to its historic turf in the Pennsylvania Wilds, including the Allegheny National Forest, as part of a long-term plan tied to habitat health and biodiversity.

“Putting a missing piece back into place strengthens the entire ecosystem,” says the agency’s furbearer biologist, Tom Keller. “When you have healthy wildlife and healthy forests everyone benefits, including humans.”

Keller spent two years assessing tree height and canopy density, land cover, annual snowfall, prey availability, and other factors, all of which bode well for reestablishing the marten. He has toured the state in recent months pitching the proposal, primarily to sportsmen, some of whom have expressed concern about marten predation on a few of the species they hunt, notably ruffed grouse — which, owing to declining numbers, have “greatest conservation need” status — and turkeys. Data shows, though, that because martens prey mostly on rodents, impacts to upland birds, or to snowshoe hares — a hunted, but conservation watch-list species — would be minimal, Keller says, noting that, as omnivores, martens also eat nuts, berries, and other plant-based forage, and insects. If a viable marten population eventually is developed, it would be managed, in part, through regulated trapping, although growing a harvestable number could take decades. The marten’s natural predators include hawks and other birds of prey.

The prospect of marten reintroduction is supported by over 90 percent of more than 1000 respondents in each of two Penn State University surveys, and by eight out of 10 participants in a poll conducted by the Virginia-based research firm Responsive Management.

The board took an important step in that direction at its September meeting by voting to release a draft 10-year reintroduction and management plan for public review https://www.pgc.pa.gov/Wildlife/WildlifeSpecies/Pages/American-Marten.

Pennsylvania lost the marten at about the same time that several other species disappeared from Penn’s Woods or were pushed to the brink by the unbridled exploitation of the habitat they shared.

“We were providing so much timber and other resources to build our state and the nation that our old-growth forests were pretty much cleared by the early 1900s,” Keller says. “The overall ecological community was devastated because our forests were gone.”
More than a century of forest regeneration and enlightened wildlife management have helped to gradually rebuild populations of woodland species that now are thriving, including Pennsylvania’s state mammal, the white-tailed deer, and, in most areas, turkeys.
 
Pennsylvania’s legacy of species restoration also includes bald eagles, elk, ospreys, peregrine falcons, and beavers — as well as river otters and fishers, both of which, as mustelids, are related to martens Bobwhite quail, another lost native, will be considered next year.

Every species performs a service for the good of the whole, Keller says.

“What’s most important with martens is that because they supplement their diet with vegetation they disperse seeds [in their droppings] — and over a wide home range — which leads to new plant growth. They also help keep populations of mice, shrews, voles, and other small mammals in check.”

There may be other services, too, Keller says. “We’re always discovering new things. Reintroducing the marten will provide a great opportunity for learning what some of those are.”

Cultivating a population from scratch would begin with importing live-trapped martens from other states east of the Rockies, and Canada, Keller says.  “We would bring them in from a variety of places to ensure genetic diversity from the ‘get-go,’ and give the population a healthy start.”

Subpopulations of about 60 martens would be established in large tracts of contiguous, forestland in northern Pennsylvania elevated enough to be resilient to climate change, and then monitored with GPS telemetry to see which groups are surviving best in relation to their habitat, Keller says.

Although martens historically were found in other parts of the state, their forests have become too fragmented to sustain the species now, Keller says.

Loners by nature, martens come together only to breed, which begins when they are about 15 months old, and they use an unusual reproductive strategy — delayed implantation — to optimize chances of survival. This means the fertilized egg won’t begin developing in the uterus until food and other environmental resources are abundant, Keller says, noting that embryonic diapause can continue for the better part of a year.

“It’s been found in some cases that if resources aren’t favorable and the female experiences stress or starvation, implantation will continue to be delayed beyond the norm for an extended period of time.”

The mother moves her kits from den to den as they mature, selecting tree cavities and other spaces too small for males to enter. About two babies out of a typical litter of three make it to adulthood.

The marten’s large, semi-retractable claws allow it to scramble up trees to hunt or rest, and its sleek body and short legs enable it to rummage under logs, root balls, and other structures to forage and find cover that bigger predators can’t access, which is particularly advantageous in snow, when resources are more limited. Martens weigh one to three pounds and are about two feet in length. They have bushy tails and lush coats.

Although demand for their fur has plummeted in the U.S., it remains relatively high in China, Korea, Greece and other countries, especially for making hats because it is soft and lightweight. A pelt fetched about $30 last year. Many states have successfully stocked martens to the delight of trappers as well as wildlife watchers, says Keller, who notes that they are the most commonly reintroduced furbearing species in the U.S. 

“The marten is one of those key species people want to see continue and thrive,” says Ed Marx, northeast project manager for the nonprofit Wildlands Network, which promotes wilderness preservation and biodiversity throughout North America. 

“The Pennsylvania Wilds is one of just a few large core areas with contiguous habitat, much of it publicly owned and protected, where there’s sound reasoning for reintroduction. The Adirondacks is another.”

A recent entry in the Adirondack Almanack says marten sightings are not uncommon given the animal’s “sense of curiosity about intruders and lack of fear in approaching hikers from the safety of an overhead limb or the trunk of a tree.”

Sloan MacCrae, marketing director for the Carnegie Museum of Natural History in Pittsburgh, can attest to that, having encountered a marten while wilderness camping in the Adirondack High Peaks in 2005.

“We were striking camp when we noticed a little creature in a tree checking us out,” says MacCrae, who lives in Oakmont. “It was small and super cute and had a very beautiful, reddish coat.”

Keller would like Pennsylvania to one day offer similar opportunities to people who enjoy the great outdoors. “Everyone I’ve talked to who’s seen a marten says it’s a really special occurrence,” he says. “Seeing wildlife is the whole reason we go out there — not to be separate from the natural community, but to be part of it.”