The thought of cuddling up under a blanket of snow in the middle of winter isn’t very appealing, unless of course you are a grouse. On those winter nights with clear skies and a sharp wind I often think about the wildlife that inhabits the north woods. Coming from a warmer part of the nation it seems counterintuitive for an animal to bed in snow when there are other options. However, when one thinks about the extreme temperatures here in northern Minnesota and the insulative quality of snow, it begins to make sense.
While some wildlife such as black bears and whitetail deer put on fat for winter, other species groups such as birds do not have the luxury of carrying extra weight. Many species of grouse make it through the winter by eating as much high calorie tree and shrub buds as they can just before sun down and spending the night under the protection of thermal cover. Thermal cover can be thought of as any living or non-living structure that limits the effects of wind and temperature on an animal. If you can imagine the difference between sitting on a bucket on the ice in the wind versus sitting in an unheated fish house on that very same day you might be able to relate the importance of thermal cover
Even the simple act of removing wind from your environment can make a big difference in your ability to stay warm. For grouse, the best thermal cover is light fluffy snow that is greater than 8 inches deep (also known as roosting snow). If good roosting snow is not available the second most preferred thermal cover for grouse tends to be young or densely growing conifers.
Grouse can enter the snow by either diving in while in flight or shuffling in one place until they are submerged under the snow. Once a grouse is under the surface of the snow they tend to tunnel away from their point of entry to confuse predators and conceal their final location. While under the snow grouse are well insulated from the outside wind and cold and remain closer to their thermal neutral zone than they would if they were roosting above the snow.
The thermal neutral zone is the temperature at which an animal does not have to burn extra energy to stay warm. As the snow melts in spring it reveals the depression made by a grouse as it slept under the snow. The depression is easily spotted as it is either stained yellow or contains numerous yellow to brown grouse droppings. The yellow comes from the pollen they eat when consuming catkin buds of various deciduous species. The ruffed grouse is just one of the many amazing wildlife species that is well adapted to surviving winter in our area. Every species has a strategy for surviving our harsh winters and their wide range of adaptations is something we are fortunate enough to enjoy contemplating while standing next to the furnace.
