Living in the North and spending as much time as possible in the out-of-doors, I have always noticed and been intrigued by how many birds stay in our area through bitterest cold and heaviest snow and ice. Hiking through the woods in 20 below weather, I see hundreds of chickadees, kinglets, crows, owls, and other birds all looking healthy and apparently thriving in the bitter weather. As scientists study bird behavior in these cold climates, we find an incredible number of different methods are employed to beat the cold.
Many birds like the grouse will dive into snow drifts and spend the coldest periods under two feet of snow where the temperature is 6O degrees F higher than the outside temperatures. Many birds like pheasants and turkeys have counter-current heat exchange systems in their legs in which the arteries run alongside the veins. The returning cold venous blood is warmed by the arterial blood so much less heat is lost.
An interesting heat conservation system is involved in the roosting patterns of birds. Birds frequently nest in groups, but these groups are not just random accumulations. The birds approach a nesting tree, making calls as they approach. Mating pairs will nestle up to each other instantly, as will siblings. The birds in the center hunch up with their bills pointed up. Birds on the edges hold their heads to the side. Even just having three birds in this arrangement reduces heat losses by 37%.
Another method of surviving cold weather in birds is their eating behavior. Studies on chickadees have shown that at the start of a day, they will have no body fat at all but, by the end of the day, there are layers of fat layered in the sternum to be turned into heat. Many birds shiver to activate the heat production process. Some lower their body temperature to reduce the heat losses. Some owls even crouch on a frozen carcass, ussing their body heat to thaw out their food.
The importance of life continuing even during cold periods is obvious. The ingenious ways that living things survive and prosper in the cold speak of planning and design. Trial and error does not work for these cases because error means death. We can know there is a God through the things He has made. (Romans 1:19-23).
References: Natural History, February, 1993, pages 4-9 and Sports Afield, December, 1990, page 42
The Incredible Immune System A War Machine Ready to Fight
Just 20 years ago, scientists had only fragments of information about how the many cells that make up your immune system interact to protect you against disease. Through -advances is cancer research, scientists now believe more than 100 million immune cells exist. For every virus or bacterium, there seems to be an inumune cell specifically designed to hunt down and destroy it. -Mayo Clinic Health Letter Medical Essay, February, 1995, page 1.
The world in which we live is ruled by microscopic organisms. These small panicles of life are the real workhorses of all life. They help our bodies digest food; they aid our reproductive systems; they decompose our wastes, prepare our soil, purify our water, and supply nutrients to our animals. Sometimes, due to mutations or other changes, they attack our bodies, making us ill. As the quote from the Mayo Clinic above says, we have a carefully designed system in our bodies which elminates the microscopic organisms that would do us harm.
The complexity of this system is astounding. It begins with the cells that actually do the fighting. There are three basic types:
B and T Cells. These are white blood cells which recognize and coordinate an attack on specific invading microorganisms.
Phagocytes. These white blood cells eat up anything that is not wanted. One kind of phagocyte called a macrophage gets rid of worn out cells and debris.
Chemical Killers. These white blood cells release powerful chemicals that destroy microorganisms.
Each of these cells carries the same chemical identification card with a unique molecular pattern on it so that your immune system does not attack itself.
Your body has an elaborate defense system designed to stop microorganisms at all places where they might enter your body.
Tonsils and Adenoids--which contain immune cells that protect your respiratory system.
Spleen--which has immune cells that destroy organisms that have entered your blood stream.
Appendix and Peyer's Patches--which contain immune cells that enter through your digestive system.
Lymph Nodes--which house B and T cells.
Lymph Vessels--which transport immune cells to your blood and immune organs.
Bone Marrow--which makes immune cells.
Thymus--where white blood cells mature into T cells.
Even in our simplified explanation, it is obvious how sophisticated and elaborate this system is. An undamaged immune system can keep us healthy and free of disease, especially when cared for properly. David's statement takes on a special meaning with this knowledge of God's marvelous design. "I will praise thee Lord, for I am fearfully and wonderfully made" --Psalm 139:14.
Back to Contents November/December 1995