Before the winter is over, Grundy County will be hit with another bone chilling cold spell. Many people bundle up, trying to keep warm when the thermometer dips below zero. Now, take a look at your feathered friends, and try to imagine what they are going through when the weather gets cold.
This website brought to you in part by the following sponsor:
The sparrow that is sitting in your tree looks exactly like it did this summer when the temperature was a balmy 98 degrees. So why doesn’t it freeze to death when the weather gets as cold as it has been recently?
The fact is, a bird has many defenses against cold weather. The first defense would be their feathers. Feathers, as many people that own down-insulated clothing know, are natures’ best insulators. Even though the sparrow may look the same as it did this summer, it actually has as much as one-third more feathers than it did when the temperatures were warmer. Just like the family dog puts on more hair in the winter and sheds it in the spring and summer, birds put on more feathers and molt them in the spring of the year. Remember the bright yellow gold finches that visited your yard this summer when the dandelions were seeding? Those are the same dirty yellow finches that are feeding at your finch feeder this winter. The difference in color is due to the fact that they have put on more, less flashy, feathers for the winter.
Underneath the outer layer of feathers, birds have a layer of feathers known as “down.” This layer is next to the bird’s skin and is used to trap air that is needed for insulation. You may notice that when the weather gets extremely cold, birds tend to ruffle their feathers more. If you are like me, you may think that the birds would get colder with their feathers ruffled, but in fact, they stay warmer. When a bird ruffles its feathers, it allows more air to be trapped by the down, which in turn provides more insulation.
Another defense against cold weather tends to make the bird look “headless.” Most people know that when a bird sleeps, it usually tucks its head under its wing. The reason for this is to reduce heat loss through the nostrils. Just like when your mother told you to put your hat on to keep you warm, the majority of the bird’s body heat is lost through its head. By covering the head, heat loss is minimized and the bird stays warmer.
You may also notice that roosting birds will tuck their feet into their feathers to cover their legs and feet. Or, active birds will perch on one foot at a time, changing from one leg to the other periodically. This, too, is done to help conserve energy and heat. The temperature of exposed legs and feet can be lowered to just above freezing by an elaborate arrangement of vessels that can exchange heat. This reduces heat loss through the bare skin and insures that the vital organs remain warm. These are the same vessels that are used by waterfowl when they walk around on the ice, or swim in the frigid water. Without these vessels the birds would loose their legs and feet to frostbite or they might even die.
On the coldest of days, birds have to stoke their internal furnaces by feeding almost constantly. A drop of 20 degrees can double their metabolic rate. If birds cannot find enough food to satisfy their needs, they will become weak and they will not be able to fly to find more food. If this happens, they will probably suffer a slow, agonizing death. The only hope they have is for the temperature to warm up before they die.
So, if you are among the millions of people that enjoy feeding birds, don’t be surprised if you have to increase the food supply as the temperature drops. And don’t be surprised if the birds seem to stay from daylight to dark, especially if the thermometer dips below zero!