Winter Ways of Wildlife
WINTER poses a problem for teeming numbers of earth’s wild creatures in the northern climates. They solve the problem in many different ways. For example, snow is evidently more friend than enemy to many of these wild creatures, since it is an excellent insulator. ‘Let the snow come’ is their tune.
And so when a blizzard bothers the white fox, he just digs deep into a snowdrift. Curled up with his bushy tail covering his nose, the white fox then sleeps out the blizzard. When fierce winds disturb the cottontail rabbit, he may make a cavelike niche in the snow, letting the wind pack the drifting snow around him. The rabbit’s own body heat warms up the cavern, and the snow protects him from the wind.
Cozy, snug conditions—these are what a great number of small rodents find under the snow. Winter temperatures at ground surface seldom fall below 20° F. even in Alaska or Siberia, where the air temperature might drop to 50° below zero F. Making nests and runways under the snow, they merrily go about their business, finding that the snow protects them not only from the cold temperatures above but also from many of their usual predators.
Some birds, too, take advantage of snow. The ptarmigan, an Arctic bird, frequently dives into a snowbank to sleep for the night.
To many creatures, the best way to deal with winter is to sleep through it or at least much of it. So when winter comes and humans may busy themselves ice-skating on a pond, they do not see any frogs around. This is because the frogs, like a number of other cold-blooded creatures, have gone to sleep for the winter. The frogs find themselves a nice bed of unfrozen mud at the bottom of their favorite pond. But before they do this, they eat plenty of food, so that once they go to sleep they need not be concerned about meals.
Snakes in northern climates also find themselves a good place to snooze when winter comes. They search out hollow logs or a bed under a stump. A cave or rock den also makes a good sleeping place. Certain caves almost become a hotel for snakedom. In the mountains of Pennsylvania, a den was found that housed almost 200 sleeping rattlesnakes and copperheads.
Eating well before winter comes, snakes live off their fat during their winter snooze. As winter goes on, of course, they use up their fat. Thus, in late winter a naturalist once saw timber cutters wake up a big rattlesnake from his sleeping quarters under a large log. During his sleep, the rattler had used up so much of his fat that, as the naturalist said, the snake’s skin “hung on him almost as loosely as it appears to hang on the sides of an elephant.”
There are also a number of warm-blooded creatures that slumber through the winter. Take, for example, the groundhog by the name of woodchuck. Mr. Woodchuck digs himself a burrow and ensures privacy by sealing off his sleeping chamber with dirt scraped from the far end of the room. Then he rolls up into a ball and sleeps away, sometimes as long as six months! Naturalists have dug up dozing woodchucks and found that these hibernators breathe only about a dozen times an hour. The pulse rate may drop from a normal rate of around eighty or ninety beats per minute to five or less. And the animal’s temperature may drop to around 40° F. Once asleep, Mr. Woodchuck is insensible to sound or touch. You could roll him across the floor, for example, without waking him up. No insomnia for woodchucks!
Such deep sleep seems to make hibernators immune to many dangers. For example, a slumbering hedgehog was placed under water more than twenty times without drowning. And scientists put a sleeping marmot in an airtight jar filled with carbon dioxide. Remarkably, they found that this winter sleeper suffered no harm after four hours. So deep is the winter sleep of such creatures that waking up is a slow process requiring prolonged exposure to heat. Perhaps the all-time high in hibernation was registered by a young female ground squirrel, which slept for thirty-three weeks out of the year! Only nineteen weeks of activity, and back to sleep again!
Compared to woodchucks, ground squirrels, snakes, frogs, and so forth, the winter sleep of many bears is only a series of naps. This is because the slumber of bears in the winter may be disturbed, since their body temperature remains high and their breathing stays at a normal rate. Not regarded as true hibernators, bears can be easily aroused from their nap. Some even wake up on their own accord in the winter and prowl around for a few hours or days.
Of course, napping bears prefer not to be disturbed by anyone, not even by out-of-season warm spells. Scientists who studied grizzly bears in Yellowstone National Park found that they chose dens where they would not likely be disturbed; some dens were on canyon walls. All the dens were on slopes that faced north, so that brief warm spells would not warm up the den and wake up the occupant. The dens were cozily lined with the fine insulation of pine and fir boughs. But just when did grizzly bears enter their dens for their winter snooze?
Over a period of years, the scientists discovered that grizzlies did not enter their prepared dens for slumber until the onset of a blizzard, one that would quickly cover their tracks as they entered their dens. In a few hours, drifting, blowing snow covered their footprints, and now who would know that a dozing bruin was in bed?
Just as some humans head for southern climates with the approach of winter, so do many creatures of the wild, especially the birds. In fact, about two thirds of all species of birds in the northern United States and Canada (about twelve to fifteen billion birds) fly southward, to southern states and Mexico or to Central and South America, for the winter. Of course, for birds the trip southward is not just to get away from the cold; they need to travel to a warmer climate to make a decent living. During the summer up north they live on seeds, berries and insects. But in the winter not only are such tasty tidbits in short supply, but there is also a shortage of daylight hours in which to search for any available food.
The trip south, for many birds, is a long one. For instance, with winter’s approach, white storks from Europe travel as far as South Africa. And, oddly enough, young storks that have never yet been away from home travel first, without an older bird to show them the way. The yearly round trip of Mr. and Mrs. White Stork and family may cover some 14,000 miles! Truly as the Holy Bible says about the stork’s God-given instinct: “The stork in the sky knows the time to migrate.” (Jer. 8:7, The New English Bible) The wonderful winter ways of wildlife are indeed a credit to the Creator of all these creatures.
Consider this fact too: Many of the southward-bound feathered voyagers fly virtually entirely over water, making long trips nonstop. A Pacific subspecies of the golden plover lives in the Alaska tundra during the summer. In the fall this bird travels 3,000 miles over the Pacific Ocean to Hawaii! As if Hawaii is not enough of a trip, this bird will continue south for another 2,500 miles to the Marquesas. Not infrequently it will fly 500 miles more to the small South Pacific islands of the Tuamotu Archipelago.
Other Ways to Deal with Winter
Heading south, if you can do it, may be the ideal way to beat the cold, but for creatures that cannot fly, it is mostly out of the question. So a common way of coping with winter problems is to store up food supplies. The red squirrel enjoys mushroom meals and so stores up quantities of these during the summer. First, though, he dries the mushrooms by laying them out on the topmost tree branches. Then he stores them in a dry place, ready for winter use.
Putting on special winter coats is a common way many creatures survive the cold. They grow heavy coats specially equipped with a layer of fine, soft hair next to the skin.
Long before man started to manufacture coats with airy padding, the deer was taking advantage of dead-air space—heat traveling very slowly through still air. So with the approach of autumn, the deer sheds its cool summer coat and grows its winter coat, each hair of which is hollow. Covered with this air-insulated coat, the deer needs nothing more, even on the worst days, than finding protection in the deep woods among the pine and spruce.
But whereas a deer might get stalled in deep snow, the snowshoe rabbit cares not how deep the drifts get. Why is this? Well, with the approach of winter, new white fur grows abundantly on the rabbit’s feet. By the time snow is on the ground, the rabbit’s feet have been transformed into broad, soft light pads to carry him over the deepest drifts without sinking.
Right now in the northern hemisphere countless kinds of animals are coping with winter’s cold and winds. They may be asleep in a den or beneath the snow or bounding about the countryside. Amazing indeed are the winter ways of wildlife!