An Outdoor View: It's a jungle under there

Posted: Friday, November 19, 2010

When snow covers the ground with a thick blanket, which it's doing as this is written, the space between the ground and the snow cover becomes a whole new world.

This "subnivean zone," as it's called, forms when heat from the gound melts snow near the ground. It's anything but a peaceful place. It's a jungle, where prey is stalked, killed and eaten by voracious predators.

Here on the Kenai Peninsula, the king of this winter jungle is the short-tailed weasel, or ermine (Mustela erminea). From the tip of its long nose to the tip of its tail, it reaches a length of 15 inches, and it weighs up to 7 ounces, but what it lacks in size, it makes up for in ferocity. "Quick," "persistent" and "fearless" aptly describe it. In summer, it's fur is medium- to dark-brown with yellowish-white underparts. In winter, it's white except for the tip of its tail, which remains black all year.

The short-tailed weasel has to eat enough meat daily to equal at least 40 percent of its body weight. On the Kenai Peninsula, it lives mainly on voles, which are mice. In snow-covered areas during the winter, voles build runways in grass. The weasel, moving sinuously through these tunnels, finds voles mainly with its keen sense of smell. When attacking, it usually pounces with its forefeet, holds down its prey with its sharp claws, then bites the back of the vole's neck until it's dead.

During winters that create ideal conditions in the subnivean zone, vole populations boom, and weasels thrive. Even when full of vole meat, they keep right on killing, storing what they can't eat in caches, not unlike what Alaskans do with a surplus harvest of moose or salmon.

Shrews, the smallest of the mammals, also live in the subnivean zone. Much smaller than weasels, they're every bit as b-a-a-d. They range in size from 3 to 6.5 inches in total length. They're sometimes mistaken for mice, but shrews aren't rodents. They're insectivores. Shrews have tiny eyes and poor vision, but acute senses of smell and hearing. With sharp little teeth, they eat insects, spiders and other small invertebrates. Like weasels, shrews have voracious appetites. Their high rate of metabolism drives them to eat an amount of food equal to 80 to 90 percent of their body weight daily!

To give you an idea of how a shrew rolls, dig a hole in the ground and put a 3-pound coffee can in it, so the top of the can is flush with the surface of the ground. Bait the can with a small piece of bacon. The first shrew to come along will jump into the can, and won't be able to get out. One of the shrews will then eat the other. The next shrew that comes along will also go into the can, etc., etc., etc.. Theoretically, when the can fills up high enough with shrew feces and shrew bones, the last shrew standing would then be able to climb out.

Between the shrews and the weasels, life in the subnivean zone must be short, but quite interesting, while it lasts.

Les Palmer lives in Sterling.

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