Subnivean now there's a word you don't see or use everyday. Subnivean means "under snow". It is the area or habitat between the snowy blanket and the earth below. It is comprised of tunnels and gaps. And with each snow event, we shovel and fight our way over the top - often unaware of the activity taking place below us. Now we haven't had many snow events this winter. And the snow moving part of me is certainly not complaining about that! But there are animals who are adapted to living quite comfortably below the surface of the snow. And for them, this winter may have been a little bit more challenging.
These special areas provide small animals with shelter from the elements, access to their food, and protection from predators. Without the snow they are more vulnerable to predation.
The thick covering of snow actually gives many small animals their only chance at surviving the winter season.
As the first snows fall, some of it is kept from reaching the ground by the grass and other vegetation. This creates natural gaps of air between the layer of snow and the ground. The gaps are then connected by tunnels dug by mice and voles. These spaces are further enhanced over the remaining winter months as the warm ground melts under the snow and the water vapor freezes to the undersurface of the snow above it.
The blanket of snow serves as a great insulator and moderates temperatures in the subnivean. Even when the above snow temperatures drop to subzero, subnivean temperatures remain at or near freezing point. And being able to move under the snow is a great advantage to small mammals that are the main diet of hungry foxes, coyotes, hawks, or owls. Have you ever watched a fox moving over the snowy terrain suddenly stop, cock his head and then dive after the sound of a small critter moving through one of these subnivean tunnels? One predator small enough to traverse the subnivean, however, is the short-tailed weasel as it searches for its prey.
As winter turns to spring, watch for the leftover signs of the tunnels following snow melt.