The winter season presents a series of challenges for wildlife, such as food shortages, cold temperatures and large snowfalls. Fortunately, many species have physiological and behavioral traits to help survive and thrive in New York’s cold winter climate.
Staying warm can be a challenge through the cold temperatures, wind, and moisture of winter. Many mammals wear their protection from the elements by growing a thicker coat of hair for the winter. Deer and moose hairs have a hollow core in each hair, which traps air for better insulation. The title for densest winter coat in New York goes to river otters. Otters’ tightly packed hair is coated with oils and performs a role similar to a surfer’s winter “drysuit”- trapping air in the undercoat to keep their skin dry during winter swims. In the case of snowshoe hare and ermine, their fur changes colors in the winter from light brown to a stark white which helps them blend in with the surrounding snow and hide from predators. Of course, the oversized hind feet that give the snowshoe hare its name are also a very useful adaptation for floating on the snow.
Beyond having a thermal coat, most species will seek an environment within their ecosystem where conditions are relatively milder. White-tailed deer gather during times of deep snow and spend more time in dense conifer stands, sunny south-facing slopes, or sheltered suburban environments. This deer behavior is known as yarding, and it allows deer to share the best food, shelter, and movement trails. During elongated cold spells, don’t be surprised if you see large herds of deer in your neighborhood.
When deep snow covers the ground, a sheltered environment becomes widely available to many small animals under the snow. When snow is six inches or deeper, the temperature at ground level under the snow typically remains just below 32 degrees Fahrenheit, even when the temperature above the snow may fall well below zero. This stable environment under the snow referred to as the “subnivean zone.” Ruffed grouse will torpedo head-first into fluffy snow and then shelter within the tunnel they have created, known as a snow roost. Ermine, small rodents, martens, and shrews build tunnel systems under deep snow where they are protected from wind, extreme cold, and the eyes of some predators. They are not entirely safe from predators above the snow, though! If you see a fox listening carefully and then pouncing into a snowy field, it is likely hunting by ear and trying to pin rodents it hears moving under the snow.
Storing food can help animals feed themselves through the winter. Many species of rodents (squirrels, chipmunks, etc.) will store food in what is known as a cache during fall and then utilize those caches throughout the winter. Beavers will remain active throughout winter and will not only cache food like fellow rodents; they will maintain open patches of water in the surrounding areas of their den to allow periodic passage in and out.
Black bears ensure their winter calories by putting on additional weight during autumn, then surviving on stored fat while sheltering through the winter in a den. A bear den may be a hole in the ground or a cave, but bears also commonly den above the ground in thick brush piles or hollow trees. Black bears dramatically reduce their activity, metabolism, and body temperature during winter through a process called torpor. Bears in New York typically enter their dens during November or December and emerge during March or April. Female bears will also give birth to cubs in the den, typically one to four cubs born during January and February. The newborn cubs will nurse and grow inside the den, so they are strong and healthy when spring arrives and they begin to travel with their mother.
While New York winters can get frigid and the snow can pile up, rest assured that our native wildlife have developed ways to not only survive winter, but to thrive in it.
