The Subnivean Zone
Weasels in their winter coats
Last year at this time I was fascinated with tracks in the snow. With a walk through the field, I could reconstruct an entire evening of animal life. This year it's so cold that I've stayed in and spent time thinking of the wildlife that exists under the snow instead—the space between the bottom of the snow pack and the warmer ground below. Trapped moisture there rises and freezes, making a roof-like structure several inches high. A world exists there filled with rodents, insects, grasses and seeds. Many series of tunnels, bed chambers, living and feeding spaces blanket any area where snow has accumulated.
This subnivean zone is cut off from the normal sky with a cave-like cover. It is active when temperatures are well below freezing. Weasels hunt the tunnels for mice and voles. Mice and voles feed, sleep and even reproduce during the months of snowpack. Owls, coyotes and foxes break through the crusty top layer and reconnect the separated worlds. All levels of wildlife would find it hard to survive long winters without the nourishment provided from this special world.
Today, instead of walking, I peer through the window and notice a fox breaking through the crust and listening and watching. He is connecting to that subnivean zone to sustain himself. His tracks reveal a constant search for this little known or observed space. We owe it to ourselves to at least imagine the active lifestyles happening there each winter.