Life Under the Snow
When I look out my window, Winter has put a white blanket on the ground as far as I can see. It looks untouched and very peaceful. The other day, when I was filling the bird feeder in front of the house, I noticed quite a few holes in the snow. They were the size of a quarter and not vertical, but horizontal. I was puzzled. But watching them from the bay window of the house, I saw little field mice and red squirrels poking their heads out, grabbing some bird seeds and disappearing into their holes again.
I had just found an entrance to the “Subnivean Zone”, a place under the snow where field mice, voles and other animals make their cozy winter homes. Subnivean Zone is a scientific term, meaning under the snow. Vegetation, leaf debris or branches help to physically hold up the snow, which forms an open space which will be used by small mammals. The interior tunnel walls form into a hardened layer as well, making the tunnels more durable. This is probably due to the packing of the walls by the residents’ bodies as they move through them, the freezing of the exhaled moisture in their breaths and air drafts in the tunnels. I first noticed these wandering lines in the melting snow one Spring as the snow cover slowly turned to a slushy, semi-transparent, grey layer on my back lawn. I could see white, rope-like lines snaking along the ground on the surface of the lawns.
Much like our classic image of the eskimo igloo home, made from cut blocks of snow, this habitat offers a constant interior temperature of around 32 degrees or more, regardless of the colder temperatures outside. Indeed, temperatures inside a classic eskimo igloo can become quite comfortable, despite the fact that the abode is made of ice! The heat from their bodies, the condensation of the moisture in their breaths and the warmth from the small seal or whale fat candles used for light, help create a refrozen layer of ice on the interior walls that adds stability and sealing inside. Add some caribou, wolf or bear hides for bedding, and you have a very livable abode!
What mankind wrought with the igloo, was just a re-creation of the dens in the subnivean world, where animals have used dead leaves, grass, etc. as insulation and bedding.
The subnivean zone has a lot to offer. It protects those small mammals from the cold temperatures, bitter winds and many of the hungry predators. It takes only six inches of snow for a sturdy roof and ample living space to be formed.
Many animals like mice and voles depend on this habitat under the snow for winter survival. They eat plants, seeds and bark from shrubs. They also store up small amounts of food to make sure there is always something to eat. They can be active all winter, but they may also huddle together in a deep sleep.
They have a series of tunnels under the snow to make travel easier. Those tunnels are highways between their sleeping quarters to my bird feeder and caches of food they gathered in the Fall. Of course, those holes also act as ventilation shafts between their home and their food supplies.
The subnivean zone has a lot to offer. It protects those small mammals from the cold temperatures, bitter winds and many of the hungry predators. It takes only six inches of snow for a sturdy roof and ample living space to be formed.
Many animals like mice and voles depend on this habitat under the snow for winter survival. They eat plants, seeds and bark from shrubs. They also store up small amounts of food to make sure there is always something to eat. They can be active all winter, but they may also huddle together in a deep sleep.
They have a series of tunnels under the snow to make travel easier. Those tunnels are highways between their sleeping quarters to my bird feeder and caches of food they gathered in the Fall. Of course, those holes also act as ventilation shafts between their home and their food supplies.
Living under the snow offers a lot of protection, but owls for example can hear rodents running in the tunnels from 30 yards away. Forming a ball with their feet they are able to punch through the top layer of snow and grab their prey. Foxes and coyotes detect animals under the snow by scent and sound as well and will pounce and dive right in for the meal. I remember one Winter watching a red fox trot across the unbroken expanse of snow in a field near the house. He stopped suddenly pricked his ears forward to a spot about a meter to his side and began to twitch his head slightly from side to side while staring intently at the blank spot in the almost knee-deep snow cover. After a few moments, he launched himself into an arcing leap and came down like an arrow, front paws together and nose to paws, burying himself up to his shoulders. A moment later he popped up with a vole in his mouth and trotted away. At the time I thought it was a lucky grab, but I was wrong.
At the end of the winter those tunnels become visible and you cannot help but admire those creatures. The complexity and extent of this hidden world slowly emerges into view as the snow melts. There is a whole complex web of life active in the apparently barren landscape of Winter, just below our view.
There is more life around you than you can see.
There is more life around you than you can see.
RSS Feed