Hannah Irwin
Curious Nature

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January 11, 2014
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Vail Daily column: Pine martens: Quiet cousin to the weasel

Mountain lions, grizzly bears, wolves — these large apex predators are a symbol of wilderness and create awe for those who have had the fortune of getting a glimpse. Interactions with elusive creatures are a source of pride for the lucky few who cross their paths. Yet one of my own most memorable wilderness encounters was with a pine marten, the small and secretive hunter of mature forests.

If you were to see one, you might think you were looking at a young fox, due to its angular face and large, pointy ears. Upon second glance, you would notice that it’s a little too long and narrow to be a fox. Their tails are long and bushy like a fox or mink, but lack the white tip of the red fox’s tail. They have an orange or white patch on their chests, unlike minks.

Pine martens are the most arboreal of all the weasels, able to scramble between branches and leap across trees as acrobatically as a tree squirrel. However, they are equally comfortable on the forest floor. In the summer, they pursue voles, squirrels and birds, but their diet often includes more snowshoe hares in the winter.

Due to the plentiful snow in the Rocky Mountains to provide thermal protection, pine martens stay active in the winter. They grow extra fur between their toe pads which creates a snowshoe effect, helping them run across the top of snow in pursuit of hares or squirrels. They will also tunnel into the subnivean zone, deep in the snowpack where it stays about 32 degrees Fahrenheit regardless of the above-snow temperature. There, they can find warmth and hunt for rodents. Curious and intelligent, pine martens dive into hollows in the snow where voles, mice and shrews have tunneled underneath.

Since they have limited body fat reserves, they must hunt extremely efficiently to save energy and stay warm. In particularly cold or adverse weather, pine martens hide out under fallen logs, or in woodpecker cavities or squirrel’s nests. They will sometimes fall into a torpor, a deep-sleep-like state where their body temperature and breathing slows to conserve energy.

Nature’s Shy Guys

Extremely shy and weary of humans, our encounters with pine martens are typically brief. However, the snowpack makes it easy to find evidence of their activity. For starters, they mark their territories with scat piles, often high up on fallen logs or rock piles. Since weasels have a loping gait, their front and hind tracks overlap. Their tracks are round and shallow, with a length between 1.5 and 2.5 inches. You may not be able to spot their five toes, which are usually covered by fur. If the trail leads to or from a tree, it is most definitely a pine marten rather than another weasel cousin, such as the ermine.

I was walking by myself along Gore Creek this past year, when I was startled by a pine marten on the path, only about 15 feet in front of me. Each of us froze, and stared at one another for a good 10 seconds, until he turned in the opposite direction and disappeared behind a stand of trees. It was only then that I gasped, realizing that each of us had just had a rare experience, as this solitary animal rarely interacts with others unless they are food. I still wonder what he thought about my presence and what he learned about humans that day.

Next time you find yourself taking a ski break in the trees or wander near some bird feeders, look for evidence of this quiet, solitary predator. Maybe you’ll be lucky enough to join the ranks of those to whom the pine marten has chosen to reveal itself.

Hannah Irwin is the community programs coordinator at Walking Mountains Science Center. She is a self-described nature nerd who loves all critters great and small.


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The VailDaily Updated Jan 11, 2014 10:31PM Published Jan 11, 2014 04:30PM Copyright 2014 The VailDaily. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.