Critter: American marten (Martens Americana)

Photo courtesy of Wisconsin DNR

The American marten, also known as the pine marten, is a nocturnal member of the weasel family and is the only state-endangered mammal in Wisconsin. Last December, state conservation biologists began installing a network of trail cameras at 120 different sites throughout the Chequamegon-Nicolet National Forest in effort to restore its populations.

What does an American marten look like?

American martens are small slender mammals that weigh 1-3 pounds and measure 15-24 inches in length, which includes a long bushy tail and they are six inches tall. The female is about three-fourths the size of the male. Often confused with the two other weasels that live in Wisconsin, fishers and stone martens, the American marten has prominent ears, pointy face, large eyes and luxurious golden-brown fur with a yellow chest. It has been said that they resemble a bushy-tailed house cat. There are two black vertical lines that run above the inner corners of their eyes. In the winter, long hair grows between the toe pads on their feet, keeping them warm and enabling the marten to more easily travel on soft snow.

Where do martens live?

The American marten lives in mature, dense forests, preferring a mixture of conifers and deciduous trees including hemlock, white pine, yellow birch, maple, fir and spruce. Marten young, called kits, are born in tree dens late March and April and are weaned at about six weeks old.

Important to martens are fallen trees, stumps, root mounds and mature trees with large cavities, which provide prey, protection and den sites.

In Wisconsin, martens can be found in Oneida, Vilas, Forest and Florence counties as well as Douglas, Bayfield, Ashland, Sawyer, Iron and Price. They were placed on the Wisconsin Endangered Species List in 1972. Today, American martens live across Canada and Alaska and in the Sierra Nevada Mountains, the Rocky Mountains south to Colorado and the northern parts of Minnesota, Wisconsin, Michigan, and the East coast states of Maine, New York and New Hampshire.

American martens are excellent climbers and will pursue prey, red squirrels or chipmunks up a tree and may also climb trees to escape danger. On the ground the move in a zig-zag pattern, followed by a series of jumps.

What do they eat?

American martens are omnivores, meaning they eat plants and animals. Mice and other small rodents are martens’ primary prey, but they also eat squirrels, hares, shrews, birds, bird eggs, amphibians, reptiles, insects, fish, crayfish, nuts, fruits and carrion. In winter, martens will tunnel under the snow in search of mice and other small mammals. At certain times of the year they feed extensively on wild fruits. While they are at home in trees, American martens do most of their hunting on the ground.

What is their life cycle?

American martens first mate at about two years old. The breeding season is July and August and while fertilized then, the female’s eggs don’t fasten to the wall of her uterus until January or February. Young are born in late March or April, with females birthing two to four kits. They kits are weaned at six to seven weeks and nearly full grown at three months. They have a life expectancy of three to four years in the wild.

What threats do they face?

Direct predation is the major cause of mortality of martens in Wisconsin. According to the Department of Natural Resources, verified predator deaths were caused by raptors, such as eagles, fishers, other mammals, including coyote and fox, and incidental trapping.

Though trapping for martens is illegal in Wisconsin, licensed trappers hunting other furbearers accidently catch and kill some martens.

The forests that covered the Northwoods before the 1800s provided prime habitat for the American marten. With the arrival of European settlers, trappers and lumbermen who cut forests and trapped martens without regulation, the populations declined. Trapping was banned in 1921, but by the mid 1940s, martens had been extirpated from the state, until reintroductions took place, beginning in the 1950s. Additionally, forest management plans that reduce canopy coverage, create barriers to marten movements, remove large diameter trees with cavities and whole-tree harvesting for fuel all reduce marten habitat.

The photos and data captured from the trail cameras placed by DNR Natural Heritage Conservation biologists throughout the Chequamegon-Nicolet National Forest are expected to provide reliable information to aid in species recovery.