With a subnivean home, a rodent won’t have to venture to the surface very often, where they would be pretty obvious to predators on a backdrop of white snow. While safer, hiding in their holes isn’t without its risks. Tunnel collapses can crush them, melt water can flood them out, and these tunnels are not predator-proof. Smaller predators, like short-trailed weasels, can fit into the tunnels to seek out their prey. Sometimes they will even move in and take over, eating all the resident rodents and setting up a little homestead of their own! Predators with excellent hearing, like foxes and owls, can hear the rodents moving under the snow and will punch through the roof of the tunnels to grab their prey. A favorite winter find of mine is wing prints in the snow, left behind when an owl has dropped from above to grab a rodent out of their subnivean hide-away, and then taken off again.
A different kind of wing print in the snow, pictured below, can indicate not a predator attack but a snowy survival strategy. Ruffed grouse are known to keep themselves warm overnight by literally diving right into fluffy snow. When the snow is at least eight inches deep and isn’t crusted over with ice, a ruffed grouse will fly headlong into it, tunneling up to a few feet further in before settling down for the night. In his book Winter World, Bernd Heinrich reports flushing grouse out of their “snow roosts” as late as noon on his walks in the Maine woods.