What a winter! For over six weeks the ground was covered in deep snow and temperatures were well below freezing, with only very brief interludes in the 30s. A couple days in the low 40s last week gave me hope that perhaps I would soon see the ground again without its white blanket. No such luck!! It is snowing again today. . .
During this unusual weather, the mule deer (Odocoileus hemionus) that wander about our property and the general area disappeared.
Hoofed animals, be they deer, antelope, elk or even domestic cows and horses, find it difficult to walk through deep snow. It takes a lot of energy to plow a track in the snow. I read that a hundred pound deer expends seven to eight times more energy moving through 20″ of snow than it does walking on bare ground. And this is during a time when food resources are meager and difficult to find. Deep snow that has been through thaw and freezing cycles also develops a crust which can cut the skin on the animals’ legs like broken glass. In the same way humans will walk, snowshoe or ski in the same tracks through the snow, hoofed animals will follow previously broken trails or even roads.
Mule deer and other hoofed animals will also “yard up” during severe snow and cold conditions. The deer gather in larger and larger groups and stay together, usually under trees or in other relatively sheltered areas where the snow is less deep and less drifted. The snow gets packed down and the animals can move in the small area where they have yarded without expending huge amounts of energy. The surrounding trees or rocks provide some cover. And the proximity of the herd members to each other conserves warmth and protects against predation. Food may become scarce if the deer are yarded up for a long period of time. But overall, yarding up appears to help the greatest number of animals survive.
Leonard and I went searching for the missing mule deer and found them a couple of miles from our house (Modoc County CA). In a grove of junipers a group of about 75 mule deer were yarded up. Nearby was an open alfalfa shed where the deer were able to find some nourishment. They were scattered under the trees so it was impossible to get a photograph of the entire herd. Hopefully by yarding up and helping themselves to a tolerant rancher’s alfalfa supply, these mule deer will survive the harsh winter conditions.