About as thick as one of your fingers, these vents probably provide fresh air. By late winter, as the snow melts down to the tunnels, we might get a glimpse of just how abundant this vole network can be. We notice the presence of voles beneath the snow, and so do predators. Shrews and ermine take advantage of their own small size to pursue the voles through the tunnels. Shrews sometimes stay beneath the snowpack for a long time.
Ermine come and go in search of mice to eat.
Foxes, coyotes, and great gray owls give voles quite a surprise when they dive for dinner in the snow. Though we seldom see the catch, we can see the telltale impressions of feet, wings, and bodies, where a predator has plunged into the snow. Squirrels and Grouse Red squirrels often descend from trees and go under the snow to visit their food caches. They might also find that traveling beneath the snow is easier, safer, and warmer than scampering across it. Ruffed grouse roost beneath the snow to escape bitter cold.