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Whats living under the snow?

Owls can find mice even through the snow.
Owls can find mice even through the snow.
Steve Jurvetson

The deep snow we have this year doesn’t seem to have any advantages and other than insulating our favorite garden plants it probably doesn’t help us humans much. But under that insulating snow pack many animals, plants and tiny organisms are living quite comfortably. This under snow world is called a subnivean environment.

Under a deep layer of snow down near the ground the temperature stays about 32 degrees which is much warmer than the surface temperatures. After a snowfall the warmth from the ground starts melting the snow, causing water vapor to rise and form a crust on the snow’s surface and leaving a drier, light, crystalized area of snow at the bottom.

In this fluffy layer protected from wind chill and swings in temperature, mice, voles and pocket gophers happily tunnel. They tend to socialize more than they do above the snow and form little sleeping colonies in comfy nests where the temperature may rise to 50 degrees or more.

The concentration of carbon dioxide may rise under the snowpack, which benefits the buried plants but could be harmful to animals. But mice and voles make small tunnels to the surface to release this gas and they avoid low spots where the CO2 may concentrate.

Under the snow the tiny animals find seeds, dormant insects and vegetation,( including the stems of some of your garden plants), to eat and they are fairly well protected from predators, although some predators can find them through the snow. But shrews and weasels enter the subnivean world also, following the tunnels the mice and voles make and gobbling them up. They may choose to make their own nests under the snow.

Red Squirrels, those pesky small red squirrels with white eye rings also utilize the subnivean world, making tunnels under the snow to look for buried nuts and vegetation. Some may also make nests there if there are no suitable tree cavities to protect them. And when there is a good snow pack ruffled grouse dive bomb from trees into the snow, and then tunnel into the snow further, digging out a snow cave to sleep in. In the Artic seals and polar bears also make snow caves.

Plants are also happy under the snow and some dim light seeps through the snow, especially toward spring. Many seeds will start germinating, and moss will grow. Plants like snowdrops develop their buds and begin stretching to the light so they can bloom as soon as they can pop through a melting snowpack. If grass and other vegetation was buried in snow before being exposed to really cold weather it will stay green. Soil microorganisms will remain active and there are certain microorganisms that have evolved to live very well in the subnivean environment.

As deer and rabbits scavenge our landscapes and struggle to survive a brutal winter with a deep snowpack, populations of mice and voles may actually rise. Shrews and weasels fatten up on them and produce more babies. Hopefully the hard winter will result in fewer deer and rabbits being born in the spring but the mouse, vole, shrew and weasel population may be larger.

If you are a chionophile, or snow lover, you may go for a winter walk on the rooftops of creatures buried below you without any harm. Just don’t use a snowmobile on top of their homes as this will compact the snow pack and destroy the subnivean world.

There is some risk to the subnivean population as spring nears. If a warm up occurs rapidly the snow may melt too rapidly to be absorbed into the ground quickly or evaporate into the atmosphere and a wet, even flooded environment will occur under the snowpack. This will drown some animals or give them hypothermia and may also drown plants and germinating seeds. So as much as we want the warm up to come quickly there are many small creatures out there hoping it doesn’t.

Here are some additional articles you may want to read.

Treating frostbite in poultry

What you need to know about squirrels.

Keeping Livestock healthy in cold weather.

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