This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Ned Rozell is a science writer at the institute.

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While hiking deep in a forest outside Fairbanks, a bird biologist and I saw an animal the size of a cat scramble up a spruce. When we stopped, a marten clung to the tree bark by its back toes and grunted its disapproval. We traded peeks through the binoculars at the pointy-nosed creature scolding us.

Mysterious predators of the northern woods, marten are members of the weasel family with supple, strawberry blond fur, bushy tails, short legs, and long, tubular bodies. Known as Alaska trappers’ bread and butter, marten have voracious appetites.

“One trapper aptly described them as walking stomachs,” said Tom Paragi, a wildlife biologist with the Alaska Department of Fish and Game in Fairbanks. “They’re one of the easier animals to trap.”

Like other members of the weasel family, marten hunt and kill small animals, most often voles, though they sometimes eat snowshoe hares, young birds, and blueberries. Marten feed on red squirrels in other parts of North America, but in Alaska biologists have seen marten sharing squirrels’ underground network of winter tunnels without killing them.

Marten aren’t afraid to tackle animals their own size, Paragi said. He once pieced together a marten drama evident by tracks left behind in the snow. He observed where a marten paused during its wandering after seeing a goshawk perched on a low tree limb.

“The marten gave it the bum’s rush from behind,” Paragi said, adding that he could tell by blood and other marks that the marten killed the goshawk, making a meal of a raptor that could have had the marten for lunch.

“They are fairly fearless,” Paragi said.

Marten are loners, roaming forests solo except for a few weeks during the breeding season. They seem to prefer mature conifer forests for birthing and raising young, and use hollow logs for dens.

The marten is one of a few mammals able to delay part of its reproductive cycle. Marten mate in mid-summer when food is plentiful, but fertilized eggs within females don’t implant into the uterus wall until springtime, a phenomena triggered by longer days. Marten kits are born in late March to mid-April. In August, the youngsters go their own ways, beginning solitary lives that can last up to 14 years.

The adult marten Paragi studied in Nowitna Wildlife Refuge usually lived in an area of about five-to-10 square miles. Juvenile marten moved as much as 50 miles before settling into their home ranges. Rod Flynn, a biologist at the Alaska Department of Fish and Game in Juneau, found that marten on Chichagof Island would sometimes travel 65 miles, as far as they could go without swimming.

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