Advertisement This isn’t just a temporary way of coping with an inconvenience for these creatures; it is a seasonal way of life — when there is enough snow, that is. It is actually a blessing of sorts, especially when our temperatures plummet like they did after the snow fell.
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Photo by Jim Solberg |
A snow cover of around six inches has generally been found to provide enough insulation to maintain a steady temperature of around 32 degrees — downright cozy when air temps and wind chills can get well below zero. I was surprised to learn that this snowy underworld even has its own scientific name — the subnivean environment. Just as subterranean means “under the earth,” subnivean means “under the snow.”
Several small rodents in our region, including voles, mice and pine squirrels make tunnels and food chambers between the snow and the ground. There they can remain relatively well hidden from predators as well as being protected from the bitter cold.
Voles, in fact, often create complex networks of tunnels lined with grass that can be seen in spring when the snow melts. But when you look out over the snowy fields now, this subnivean activity is virtually invisible to us. Even though they remain unseen under the blanket of snow, however, there is still danger for them.
Some predators are still able to detect the critters when they move. Owls can hear them from a considerable distance and fly silently to plunge in after them. Fox and coyotes are also able to hear them, but they need to get much closer to detect the stirrings under the snow. It is fun to watch them as they twitch their ears and turn their heads to zero in on the target and then leap high to pounce through the snow on the unsuspecting rodent.
If the fox, coyotes and owls don’t get them, the wily weasel can easily wend its way through the tunnels and ambush the residents in their snowy retreats. Of course, if they pop their little heads above the snow to run errands, they are also vulnerable to a host of other predators, such as our winter raptors. These include the barred and great-horned owls as well as the ubiquitous red-tailed hawk. In a typical winter these predators will contribute in eliminating up to 90 percent of the voles.
In addition to the mammals, many insects and spiders also survive and even reproduce under, within or on the surface of the snow. As the winter progresses, I will be watching for some of these cold weather arthropods. If you look carefully, especially on any relatively warm sunny day near a stream or spring, you may even see some of these snow bugs flying about.
Scientists have also discovered that a thriving population of bacteria and fungi are active throughout the winter on soil under the snow. They feed on plant material that has been buried by the snow and they will grow and even produce spores in this subnivean world. When the snow melts in spring, I have occasionally seen ground that was covered with a filmy layer of such “snow molds.” The growth quickly dies off once their snowy environment is gone.
As you enjoy our white Christmas and Hanukah holidays, don’t assume that all those seemingly empty fields of blown and ice-crusted snow are dead zones — there may be a teeming world of life underneath.
Hawks in winter
I have seen one of our common winter raptors, the red-tailed hawk, at many locations lately. I could depend on seeing at least one almost every time I ventured into Minnesota to view the swans and eagles below Brownsville or headed north along the river toward Winona.
They often were perched on prominent tree branches, where they could watch for rodents and other small mammals along the edges of the road. If they are facing you, the white on their bellies may be what attracts your attention in the first place. In general, they prefer locations where they can perch near an opening in the woods.
They were also seen frequently on Goose Island flying over the ducks and muskrats before the sloughs froze solid. Now I still see them soaring over the island or perched in trees near the roads or sloughs. I saw one recently on one of the raptor perches put amongst the newly planted trees by the U.S. Corps of Engineers on the south end of the island. Another one landed in the tree at the entrance to Goose Island Campground and watched over the orange-tinted river ice as the sun settled behind the Minnesota bluffs. Our winter red-tails might be locals or birds that have migrated from farther north. They watch for prey from their perches or soar over the landscape looking for cottontail rabbits, squirrels and any of the subnivean rodents that dare to emerge from their tunnels.
An occasional bird might also be taken, but the trimmer profiled Cooper’s and sharp-shinned hawks are the specialists in capturing birds. As any one with a bird feeder knows well, life continues in all its excitement and drama throughout the winter.
Enjoy outdoors
Hope you all enjoy the holiday season and can somehow take advantage of the wonderful outdoor opportunities our region offers.
Whaditiz
It’s a wahoo bush, also called the “burning bush” for its red seed clusters.
