Coping with winter
Winter is coping time for wildlife. We humans as members of the planet’s most ingenious species do not necessarily endure the weather. Instead, we’ve found ways to offset the worst climatic extremes.
Wild creatures on the other hand, have to tough it out without the benefit of our central heating, electric plug-ins and high tech wonder fabrics. But nature has equipped the wild creatures who share our northern winters with good biological mechanisms and coping behaviors. Deer have a coat of hollow hair that provides and insulating blanket to conserve body heat – trapped air is a great insulator. If winter snows become deep enough to restrict easy movement from sheltered bedding areas to favored foods, deer “yard up,” gathering in traditional wintering areas in their own little groups. Their concentrated movements pack down the snow and help keep food accessible. If winter breaks and snow depths diminish so yarded deer can travel freely before food supplies are exhausted, they have a good chance to survive the worst weather. Their summer hair is solid. Their winter hair is hollow.
Ruffed grouse are blessed with the habit of roosting under the snow, when depths are sufficient and the snow soft enough to either dive or burrow beneath it. As any experienced winter trekker or camper will tell you, snow can be an excellent insulator. For grouse, the snow blanket means conserving vital body heat minimizing the time a grouse must be out feeding and exposed to predators like owls and goshawks. In the absence of good roosting snow, grouse will seek shelter in brush piles or thick conifers. Birds that winter in the north have some amazing survival mechanisms. Rather than reducing blood flow to conserve heat, as happens in human fingers and toes, birds have a special heat-exchange process. The blood vessels in their uninsulated legs are close together, so that heat from the warm blood flowing out of their body is absorbed by cooler blood flowing back into the body. This both conserves heat and prevents the thermal shock that might occur if supercooled blood returned directly to their body’s core.
Chickadees can survive under “controlled hypothermia” at the coldest times, reducing their core body temperature from as much as 107 degrees to as low as 80 degrees. If humans experienced such a drastic temperature decrease, we would die. But chickadees because they are able safely to decrease the spread between the frigid air temperature and their lowered body temperature, can actually reduce the demand on their body to generate heat. Like other birds they can also “fluff” their inner feathers, thus sealing out cold air and sealing in warm air. Even something as simple as body posture can help survive severe cold. Standing on one leg, or tucking the bill under a wing can reduce heat loss from exposed body parts.
And did you know birds fluff up by changing the angle of their feathers to their bodies? Small birds hide out in tree cavities, reducing their exposure in these tiny microclimates. Too, chickadees, redpolls and other song birds, like owls may also take shelter in the thick branches of conifers protected from the heat-robbing effects of wind. Some birds such as cardinals and blue jays change their food-gathering times to early morning and late afternoon when the winds go down. Just as migrating birds, like ducks, increase their fat reserves to fuel long distance flight, non-migrating birds in winter depend more on food-generated fats, which is why so many species are drawn to the suet we place in our backyard feeders. Suet, which is animal fat trimmed in the butchering process, is a high energy food. No wonder Native Americans and voyageurs process used the same fats to make long-lasting, high-energy Pemmican, mixing it with lean dried meat and berries. Winter is unquestionably a time that tests local wild creatures ability to survive. But nature has provided them with remarkable instincts and “equipment” to endure, proving once again that life finds a way. Bears hibernate. They don’t eat for several months and their heartbeat slows down to almost nothing. Bob White quail form a night-time small circle with their tails pointing inward. They not only keep warm on cold winter nights this way but it protects them from predators better. Foxes, coyotes and squirrels can wrap their tails around their bodies.
Ever notice songbirds in the winter? Often they can be seen perched on the limb of a tree or bush not moving a muscle, foot or wing, not even their heads. They are conserving energy, moving no more than absolutely necessary. Other animals such as elk migrate downhill moving from the colder and higher altitudes down to the lower and warmer altitudes where winter grasses and hay are available.
And there’s something about sightseeing from the seat of a nice warm car on a cold winter’s day that’s good for the soul. The other afternoon I parked the van beside the walking trail along the Boone River to see what I could see. I was in no hurry and neither was anyone else including Mother Nature. In the top of an old dead tree a bald eagle and a red tailed hawk sat nearly side-by-side on the same tree limb. Less than six feet separated the two birds. They were there when I arrived and they were still there when I left over two hours later. Now that’s patience. Several hours later – out of curiosity – I went back down to the river to see if they were still there. They were. The red-tailed hawk and bald eagle were still perched motionless on the same tree limb. I’ve been wondering which one flew away first? Which one outlasted the other? Which one had the most patience?
And now have a good weekend.