Tunnels in Snow

I've recently discovered that red squirrels and voles (field mice) dig tunnels through the snow. A couple of weeks ago we saw a vole moving in and out of tunnels under the feeders that are in front of our living room window, and my son saw a red squirrel disappearing under the snow and emerging at the base of the large maple tree near the curb. The photos below show tunnel openings I noticed yesterday, leading from our front step area (below one set of feeders, as you'll note from all the seed shell litter) and leading toward our other set of feeders -- and who knows where else.

Two tunnels I believe were made by red squirrels

Snow tunnel of a red squirrel -- perhaps with a vole tunnel to its right

Here are some photos another blogger caught of a red squirrel actually using such a tunnel. I'll keep my eyes open too, but this view of the tunnel openings isn't one I can catch without actually being outside and noticeable to the animals, and they move very quickly.

The current online issue of Audubon has an article by Jeff Hull that talks about the several layers of the snow habitat:

For many animals that don’t migrate or hibernate, snowpack provides shelter and food throughout the winter. The snow world, or nivean environment, is divided into three regions: supranivean (above the snow), intranivean (within the snowpack), and subnivean (beneath the snow). Birds such as grouse may cover themselves in powder near the surface to stay warm, while deeper snow shields mice and voles from birds of prey and foxes, coyotes, and bobcats. Tunnels that form along tree trunks and shrubs allow weasels and other small mammals to move throughout the layers. In the subnivean space, near the warmer earth, rodents such as mice and shrews graze on grass or insect eggs. And at the ground surface, fungi and bacteria communities thrive, a source of carbon dioxide that’s been recognized only in the past decade.

 The article also points out that as the snow warms and refreezes in early spring there are dangerous downsides to this otherwise protective winter habitat:

Earlier in the winter, depth hoar—fragile crystals with minute spaces between them—dominates the snowpack. Deer mice, voles, shrews, and weasels can move freely beneath and within it. Grouse often submerge themselves in soft snow as shelter from nighttime cold.

But spring’s isothermal conditions are dangerous for mammals below. Because the snow is water-saturated, it’s lost many of its insulating properties. A string of too-cold or too-warm days could be disastrous. “Should a real cold front move in, a cross section of snow could freeze and the animals could be trapped in there,” [naturalist JimHalfpenny, of Gardiner, Montana] says. This late in the winter, food supplies are grazed over. Being trapped in one place by an ice layer could limit the animals’ ability to forage, which could be fatal.

A sudden, sustained rise in temperature is equally dangerous. “Since water is percolating down, everything [at ground level] is pretty wet,” Halfpenny says. “In a real heavy melt, small mammals can get wet and get hypothermic—or, worse yet, drown. This can be a delicate time of the year for small mammals.”

During the heavy snows and frigid cold temperatures of the past couple of weeks, I've been particularly conscious of how difficult life must be for birds and other wildlife, but also heartened to discover the tunneling life of red squirrels and voles, which protects them from the elements and from predators to some extent. We try to keep our feeders full, make sure snow isn't clogging access to the seed, and sprinkle some seed and bread crumbs on the ground as well, to give a helping hand to those that can't perch on or cling to the feeders.

Christmas Snowstorm: Plop, drizzle, fizzle

Well, instead of another 8-10 inches of snow we got two or three inches of wet snow Thursday night and Friday morning, and a fair amount of drizzle and rain over the remainder of the day. The roads stayed mostly wet, though Dave did have a rather arduous drive on Highway 19 out to the interstate early yesterday morning to meet the rest of us at a family homestead in the south metro. We drove into St. Paul for delicious meals both Thursday evening and Friday afternoon and back home to Northfield in the early evening, the car thermometer reading between 37 and 34 degrees, with never a white-knuckle moment.

We dug out the very heavy wet snow from the driveway last night -- not much in inches, but a lot in weight -- but our muscles are becoming somewhat accustomed to this shoveling business lately and didn't complain too badly. (I asked my son, age 10, to help with the shoveling, but he had tossed his shovel down somewhere in the snow a couple of days ago and it was covered up and no longer to be found.) This morning, judging from the sounds made by the dog's feet when she went outside, everything has hardened to a crunchy crispness, so I'm glad we got the shoveling done.

Speaking of animals walking in the snow, on Thursday morning I found these tracks by our front door. Although I wish they were something wild and exotic, I must conclude* that they are tracks of a domestic cat. Ah well.


*Here is the animal track chart I've referred to before, provided by the Ohio DNR.

More About Animal Tracks

On Saturday, while taking pictures in the St. Olaf natural lands, I found these intriguing prints. While the impression is clearly of a large, three-toed animal, when I consult the guide to tracks I posted recently there just doesn't seem to be anything like that. Rather, the tracks appear to indicate a small hopping animal whose tiny forepaws land together first, creating a single print, with the larger hind feet landing separately ahead of the forepaws. This scenario is reinforced by the fact that the tracks appear almost in a straight line rather than staggered, as they would be if made by the left and right feet of a larger animal.

Animal Tracks in Snow

This morning I tried to identify some of the tracks in the snow just outside my front door near my bird feeders and a small sheltering evergreen. If you have any experience in this area, please consider this a request for your expertise.

The narrow trail at the left suggests perhaps a mouse -- a snaking trail with little indentations within it.

Below, you can see a couple of these trails and some much larger prints that mystify me at present. These larger prints -- 6-8 inches long -- contain a sharp double point like an "M" or cat ears at one end, a rounded but clawed-appearing other end, and deep indentations inside.

They mostly proceed in a straight line, not staggered, so I presume they reveal the hopping progress of a smallish animal rather than the giant tracks of a fearsome bear-deer.

I have consulted some track-identification guides like the one below from the Ohio DNR, but they haven't really helped.

Any insights?