How nature helps wildlife survive the harshness of winter

Len Lisenbee

Humans generally aren't bothered too much with cold weather, as long as it is reasonable. Layers of clothing, insulation for the home, modern, well-stocked supermarkets and several semi-affordable sources of home heating energy allow us to survive even the most inclement weather.

But what about wildlife? How can wild animals cope with such extended bitter cold conditions?

Nature is generally a wonderful provider. She takes great pains, through the evolutionary process, to ensure that every species is capable of survival within the environmental niche it has evolved into. Either that, or nature will send that species into the oblivion we call extinction and tailor another to fill the void.

That is the real meaning of "survival of the fittest," and it is the most unbendable law of nature.

Almost everyone knows that whitetail deer have "hollow" hairs that help them survive the cold. But not everyone understands how a hollow hair can perform that service.

Deer forage after a night of fresh snowfall, in Boulder, Colo., Tuesday, Nov. 17, 2015.   (AP Photo/Brennan Linsley)

Dead air space, like the air trapped between the glass layers of a double-pane window or between the outer and inner walls of a house, is the key. Hollow hairs have still air inside that helps hold in warm body heat and keep out winter's chill.

At the same time, the close-lying hairs trap even more air around them, adding to their insulation abilities.

Deer, like many other woodland critters, also have the ability to store fat. When available food is inadequate for their needs, or when it becomes very cold, this fat reserve is tapped for additional food (heat) value.

As long as the individual animals aren't unduly stressed by other animals such as coyotes or domestic dogs or by too many other deer competing for a limited amount of winter food, they will probably survive, and in relatively good shape.

Deep snow is another matter entirely. Two feet of snow with a thin crust is enough to cause deer to "yard up," or congregate together in groups of 10 to 50 or more animals.

The yards are most often located in a sheltered area near good food supplies. However, if the deep snow persists and deer can't move, they begin to starve once the local food is exhausted. Deep snow can prevent them from moving to new feeding areas, even if they are only a short distance away.

If deer are subjected to extremely harsh winter conditions, nature has another way of assisting in the doe's survival. If she was successfully bred during the fall rutting season, a winter-stressed doe will actually re-absorb the partially formed fetus of her fawn(s). While she won’t give birth in the spring, her body has the ability to turn her fetus into useful energy that could save her life.

Wild turkey don't have the ability to store a lot of fat, so they must rely on a steady supply of food. And while they definitely prefer some food items over others, when the chips are down they will eat just about anything edible that they might find in their travels.

It isn’t unusual to see entire flocks feeding in harvested crop fields, scratching for kernels of corn or other grains lost to the combine.

Acorns are one of their favorite food staples. During a good "mast" year, when lots of acorns are on the ground, turkey can be found scratching under oak trees all winter long. They will also eat beech nuts when available, and ash seeds are another source of preferred wild food. Unfortunately last year was not good for mast crop production, so this winter could be very hard on wild turkeys and other wildlife species.

There is one other food possibility for these big birds. Turkey will feed extensively on wild grapes and wild cherries if the mast crop fails.

Actually there is a wide array of berry and seed producing plants they will seek out during lean times. They also look for insects, worms and grubs as they scratch in the forest litter. If the snow cover does not prevent that activity.

Deep snow can have a devastating effect on turkey. If they can't walk and scratch, they have to sit. The wind generally blows some ridges bare of snow, but not always. Flocks of turkeys have been observed sitting in the same tree for more than two weeks without moving during inclement weather.

But eventually they have to eat in order to survive the cold. If their internal reserves get used up before they can get to exposed ground, they will die. Extended periods of deep snow can be a killer on wild turkeys.

People living in turkey country are often surprised to find a flock of these homely yet somehow noble birds scratching and feeding right under their backyard bird feeders.

Wild turkey are also opportunistic when it comes to winter food. While they are normally shy birds and avoid human haunts like the plague, they will come to a bird feeder as long as they feel they are safe.

But, if a human shows himself to them for even a fleeting instant, they might move off quickly, or they may just ignore the human and continue feeding. I’ve seen both several times.

Some species like the woodchuck take the easy way out. Instead of struggling to find food during the winter, they (and some other species) hibernate for most or all of the winter. The deep sleep in an underground burrow is accompanied by greatly reduced body temperature and heart rate.

Body fat supplies the minimal calories needed for survival under these condition, and usually there is still some fat left when spring arrives to aid the species with the stress of breeding and searching for some tender new shoots.

Chipmunks hibernate, too. But while the woodchuck may awaken two or three times during the winter, chipmunks become active every week or so. During these periods they visit their larder of stored seeds and grasses for a mid-winter snack. Then it's bedtime once again until the next hunger pangs hit.

Without any doubt the most efficiently insulated wildlife species has to be our local wintering waterfowl. Ducks and geese spend most of their time resting on water just a little warmer than ice.

Sometimes they even sit on the ice to rest. And when they feed it is either in a frozen crop field or under the surface of that cold water.

Nature has been kind to ducks and geese in the insulation department. A heavy coating of feathers, waterproofed by oil from a gland on their lower back, keeps wind and moisture away from the skin. A thick undercoating of fluffy yet efficient down feathers traps air (heat) next to the skin. That combination allows them to survive even the most frigid weather conditions.

Food, especially for our local wintering ducks, can be a serious problem. Many of them have become accustomed to getting free handouts of goodies from good-hearted humans on the city pier and along lake shores.

If that food supply doesn't arrive on any given day, they will still be sitting there waiting for it to arrive instead of looking for more natural aquatic food stuffs.

The greatest disservice humans can show any wildlife is to get it accustomed to feeding only to suddenly stop that feeding. Wild birds and animals don't understand when the food they have learned to rely on suddenly isn't there any more. They will continue to come to the feeding site, spending valuable time just sitting around when they should be searching for other food sources.

By the time they do start their search they may be too weak to survive. And please remember that it is illegal to feed deer at any time.

People who have back yard bird feeders face the same problem. They must be dedicated and responsible. Once the feeding starts it can't be suddenly stopped. To do so would stress the birds that rely on that food.

It is the human's responsibility to keep the food coming at all costs. Failure to do so, regardless of the reason, is a most inhuman act.

Len Lisenbee is the Daily Messenger's Outdoor Columnist. Contact him at