Capital City Carvers

Birds as diverse as kinglets, titmice, bluebirds, grouse, and penguins go one step further to reduce the amount of heat they lose. They huddle together. If one of them can pack 30 percent of its body surface tightly against one or more neighbors, then heat loss can be reduced by 30 percent. Creches formed by both young and adult penguins are based on this concept. Birds that roost in cavities, amid dense vegetation, or under snow reduce heat loss by warming the air around them, thereby reducing the temperature gradient and subsequent heat loss between them and their immediate environment.

When physical methods to reduce temperature loss are not enough, birds must increase their metabolisms to generate heat. This is especially important in small birds, which have a higher ratio of surface area to volume (body mass) than large birds, and lose more heat through the skin. But generating heat means burning calories. To make sure northern seed-eaters have sufficient fuel in winter, they store more of then-digested food products as lipid triglycerides than as carbohydrates. The higher fat content causes the finches to weigh more in winter than in summer, but the triglycerides' high caloric content is a key to survival. Heat is generated by all muscular activity, especially flying. Birds also generate heat through rapid, out-of-phase muscular contractions- they shiver. It is now believed that most and probably all northern winter birds shiver on a fairly regular basis.

Of course, there are times when physical adaptations aren't enough to prevent heat loss and heat production isn't sufficient to keep up. Under such circumstances, some birds enter torpor. Body temperature, heart rate, and breathing all drop, and the bird becomes lethargic. The state can last for days, but in most cases, torpor is simply a means of getting through a cold night. Birds typically recover the following morning by shivering and then feed actively to build up the fat reserves they'll need for another night.

Birds are indeed very remarkable creatures.

Habits in Action

(This always bears repeating)

• Clean Hands - wash your hands, they pick up dirt and transfer it to the carving.
• Clean Tools - wipe them after stropping, wipe them after you finish carving.
• Clean Bench - keep it clean of chips and dust.
• Clean Workshop - clean regularly to remove wood chips and dust. Vacuum, don't sweep.
• Clean Work - cover your work between sessions and, if possible, wash with dish soap before finishing.

A big Thank you to Ken and Lewis Digital for printing the newsletter. We would be hard pressed to do this without them.