Deep snow and new trail cameras are good news for martens, Wisconsin's only state-endangered mammal

Humans may be fed up with the snow in Wisconsin this winter, but one critter is reveling in it: the American marten. 

Wisconsin’s only state-endangered mammal, also called the pine marten, tunnels into snow to find food, including small rodents like mice. When the snow is deep, the little critters, which weigh between 1 and 3 pounds, can better evade predators like fishers, which can weigh up to 15 pounds. Deep snow also means martens don’t have to compete with fishers and other animals as much for food. 

The snow also makes it easier for the Wisconsin Department of Natural Resources to track the marten population, although a new technology is making that even easier. 

In December 2018, the DNR began deploying a network of 120 trail cameras in the Chequamegon-Nicolet National Forest to monitor martens. The setup includes a platform with bait to draw martens close enough for the camera to capture the distinctive yellow-orange fur on the animal’s chest and throat.  

In the past, the DNR used captured martens hair samples to track the population — a difficult and costly process that required tracking animals, which was harder in years of low snow cover. 

The new cameras will allow the DNR to track individual martens for years, get more accurate population estimates and monitor annual survival rates. 

"Using cameras to collect these types of data is cheaper, requires less time in the field, and is less invasive to the study animals," Skyler Vold, the conservation biologist leading the project for the DNR Natural Heritage Conservation Program, said in a statement. "Establishing long-term research and monitoring with trail cameras may help us discover more details to aid marten recovery in the state." 

Before European settlement, martens were found throughout northern Wisconsin. Their preferred habitat is dense, old-growth forest.

But by 1925, the marten had been extirpated from Wisconsin, due to unregulated trapping and habitat loss. The mammal was added to the state endangered species list in 1972, although reintroduction efforts began as early as the ‘50s.  

Wisconsin now has two marten populations in the CNNF and one in the Apostle Islands. The larger, more stable group is in the Nicolet side and was estimated to be between 160 and 282 martens in 2005.

Numerous groups are now working together to help the marten recovery, including the U.S. Forest Service, the Great Lakes Indian Fish and Wildlife Commission and tribes such as the Ojibwe; the marten is one of the Ojibwe's clan animals.

For conservationists, improving marten habitat means other species benefit, too.

"American martens are an important species in Wisconsin because they are known as an ‘umbrella species,’ " DNR conservation biologist Carly Lapin said in a statement. "Managing Wisconsin forests to improve habitat for American martens will also improve habitat for a wide variety of other species that also rely upon older forests." 

"We're optimistic about the population status of marten in Wisconsin," Vold said. "Establishing long-term research and monitoring with trail cameras may help us discover more details to aid marten recovery in the state." 

How to identify a marten

Martens are often confused with fishers, another weasel-family member that lives in Wisconsin. Here are some of the marten's distinguishing characteristics, according to the DNR:

• Martens have thick, soft fur that varies from tan to dark brown. They have red-orange throat patches that fishers do not have.
• Look for two dark lines that extend up from the inner corner of their eyes.
• In winter, long hair grows between their toe pads (like a snowshoe hare) to help keep their feet warm and travel on deep snow.
• Their bushy tails are about one-third the length of their body.
• Martens have proportionately larger ears than fishers.
• They are small and weigh 1 to 3 pounds; fishers are larger and can weigh up to 15 pounds.
• Martens are elusive and like dense, old-growth forest; they don't like to cross open areas.

Contact Chelsey Lewis at (414) 224-2144 or clewis@journalsentinel.com. Follow her on Twitter at @chelseylew and @TravelMJS and Facebook at facebook.com/journalsentineltravel.

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