Winter at Craters of the Moon

[Image: wide view of Craters covered in snow]

Craters of the Moon in winter

Douglass Owen, Park Ranger-Geologist: Winter is highly variable. There are winter days that are very cold, well below zero. There are other days that may be up in the 20’s. We actually have more calm days in the winter than we do in the summer. Wind is usually not a big factor, but we can have ground blizzards as well as regular blizzards.

Typical snowpack here is close to three feet during January, February and March, so it’s kind of a paradise for skiing and snowshoeing. We’re about 700 feet higher than Arco so we catch a lot more snow than most people realize. We’re about the same elevation as Ketchum, next to Sun Valley. Consequently, we usually have plenty of snow for skiing and snowshoeing. There’s no fee—it doesn’t cost anything to ski or snowshoe.

Joan: How does winter weather affect the area?
Doug: Winter snows are a major source of water. Freezing, thawing and frost-wedging are probably some of the major agents of change here in the park. As that water expands, it cracks the rocks apart. This is what probably causes the collapse some of the lava tubes, as you get this cross-wedging with sealing blocks.

[Image: lava sticking out of the snow]

Craters of the Moon in winter

Winter winds have a great impact on some of the life in the monument. As the wind blows snow and ice crystals, the particles abrade the terminal buds on the tree branches. Those buds don’t produce limbs, so you end up with flagging, where most of the branches are on one side of the tree. The same thing happens in the summer, when the high winds pick up the cinders that we have here and abrade those terminal buds. So it’s a combination of summer and winter effects.

A snow cover actually helps plants and animals survive the winter. When we have several feet of it, it’s a very good insulator. Very fresh snow is as much as 90 percent air and 10 percent frozen water. Consequently, the temperature down at the ground-snow interface is very close to freezing [32 degrees F], even if it’s 20 or 30 degrees below zero at the surface. So you find many little animals, particularly rodents, utilizing that interface between the snow and the ground for foraging and passageways.

If [you are an animal and] your coat is dark coat and you are running across the surface of the snow, not only are you losing a lot of heat, but also you don’t have much camouflage. You are very vulnerable to a raptor—say, a golden eagle or a kestrel or a great horned owl— and so that’s a safer environment down there. Plus, you’ve got the insulation of the snowpack itself.

Joan: Tell me about the animals that are here.
Doug:
We have 58 different mammals that live here. A number of them are hibernating this time of year, animals like our marmots and our ground squirrels. Other animals go in and out of hibernation, like the yellow pine chipmunks. Others are more active. Our bobcats, our foxes, our coyotes—they are out there hunting, as are the weasels. Other little rodents are active, too—things like voles. Our little volcanic farmers, the pikas, are down in the lava living off their hay that they collected during the summer. We’ve got cottontails, white-tailed and black-tailed jackrabbits. We’ve even got pygmy rabbits out here.

So there is a lot more life than most people realize—but the thing you see most often in the winter is the signs that they leave behind: tracks or trails or scat.

[Image: kids playing in snow]

Children snow shoeing in the snow at Craters of the Moon

Joan: What kind of strategies do animals use in order to cope with winter?
Doug:
To survive winter and there are basically three strategies. They can escape or migrate. Another strategy is to avoid winter—they go into hibernation. And then the third strategy is basically to adapt. There are many different adaptations: behavioral, physiological, and so on.

Joan: When you look out across the snow on a day like today, how do you describe it?
Doug
: I think it is magnificent. I think it is something that is awe-inspiring.

The dynamics of this place—both geologically and the adaptations of life to cope with this harsh volcanic terrain and then a superimposed, high-desert environment on top of it—it’s just remarkable. Life finds a way to cope with any environment. We have temperatures over 100 degrees in the summer, occasionally, and in the winter we can have temperatures 40 degrees below zero. You are talking about almost 150-degree temperature range that life has to cope with. It’s just remarkable. It’s just a fascinating place.

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