Monday, November 26, 2007

The Animals Are Getting Ready For Winter!

People usually spend the winter in a home with some sort of heat; they put on extra layers of clothing and heavy coats for added warmth when they go outside. When the need for food grips them, they go to the grocery store. But what about the wild animals that live around us?

The biggest problem for most animals in the winter is finding enough food. Wild animals cope with the changes in weather and availability of food in one of three ways: adjusting, hibernating or migrating. Most land-bound animals are forced to remain and stay somewhat active during the winter. They must adjust to our changing weather. Many make changes in their behavior or bodies. Cold-blooded animals (i.e., insects, reptiles, amphibians, and fish) must hibernate if they live in environments where the temperature and therefore their own body temperature drops below freezing. Box turtles burrow into the soil or mulch piles. Reptiles like lizards and snakes seek protective cover under rocks, leaf litter and mulch piles. Many others hoard food stores to get them through the winter. Squirrels and mice stash their food in tree cavities, under leaf litter, or in holes in the ground. Still other animals, such as voles, have communal food storage areas underground.

Most animals prepare for winter by changing their bodies - accumulating body fat is the most crucial, a vital insulator for warmth and source of energy. Many of these animals, like deer, squirrels, and raccoons, spend the fall feasting on energy- and fat- rich acorns and other nuts that help them put on an insulating layer of fat beneath their skin. Their sparse summer coat is gradually replaced by a warmer one made up of a dense layer of under fur and a thick surface layer that helps to trap body heat. These species, as well the rabbit, otter, muskrat, fox, and bobcat, remain active throughout the winter, foraging or hunting daily. For other species, such as opossums and skunks, winter activity is temperature dependent. During extremely cold periods they spend their time in their nests or dens, curled up in a semi sleep dormant state.

Hibernation is the practice among certain animals of spending part of the cold season in a more or less dormant state, apparently as protection from cold when their normal body temperature cannot be maintained and food is scarce. This deep sleep allows them to conserve energy and survive the winter with little or no food. Hibernation is caused by a chemical trigger released by the brain when the animal experiences extremes of temperature, lack of food, or decreased amounts of daylight. Most hibernators prepare in some way for the winter. Some store food in their burrows or dens, to eat when they awaken for short periods. Many eat extra food in the fall while it is plentiful, and store it as body fat to be used later for energy.

Hibernators have two kinds of fat: regular white fat and a special brown fat. The brown fat forms patches near the animal's brain, heart, and lungs. The fat sends a burst of energy to warm these organs first when it is time for the animal to wake up. Hibernating animals are able to store enough food in their bodies to carry them over until food is once again obtainable. They do not grow during hibernation. Their bodily activities are reduced to a minimum; in fact they may have only one or two heartbeats every minute. This energy-efficient dormant stage enables the hibernating animal to have periods of inactivity that last for weeks or even months. True hibernators go into such a deep sleep that they are difficult to wake and may even appear dead. Their body temperature drops, and their breathing and heart rate drop significantly. For example, the groundhog, or woodchuck, is one of our true hibernators. It spends most of the summer in fields and in tunnels it has dug below. During winter, the groundhog finds it way to the deepest recesses of those tunnels where it will hibernate. A hibernating groundhog's heart rate slows from 80 beats to 4 beats per minute, and its body temperature drops from 98F to as low as 38F. If its temperature falls too low, it will awaken slightly and shiver to warm up a bit.

If an animal lives in an area where the winter is mild, it may hibernate only briefly, or not at all. However, even when the winter is severe, hibernators may wake up for short periods every few weeks to use their "toilet rooms" and eat if food is available. Animals such as raccoons, skunks, and some chipmunks are light sleepers and are easily awakened. They may sleep during the most severe weather and wake to roam and forage for food in milder weather.

Our largest hibernator is the bear. Bears are unique because, unlike other hibernators, they do not eat, drink, or excrete at all while hibernating, which can be as long as six months. Although the quarters are cramped, female bears give birth and nurse their cubs during hibernation. Other true hibernators include the jumping mouse, little brown bat, the eastern chipmunk, and some species of ground squirrels.

This week, let's have some fun learning about how animals live in the winter.
Crafts, coloring pages, stories - we could even make a feeding station to help out the animals that live nearby.

If your family has some ideas we can use to learn about animals in winter, please leave a comment and I'll be sure to say Thank You!