In summer the mountains are bustling with life. Songs of birds and insects fill the air and colorful forms flash from tree to tree. In contrast, the winter mountains are quiet and still. Into what secret places have the vibrant forms of summer retreated? Where do the winter mountains hide their burgeoning life?

Some of the exuberant forms of summer die with the first frost. Many insects cannot tolerate cold and perish when the first ice crystals form on woodland soils, leaving only their eggs or developing larvae safely deposited beneath a blanket of fallen leaves.

Some mammals slip into burrows beneath the ground to sleep away the cold winter months. Snakes seek shelter in crevasses, rock shelters, or used or unused mammal burrows. Box turtles dig their way beneath a sheltering layer of soil, while aquatic turtles seek the soft mud at the bottom of shallow pools. And many of our most colorful birds simply fly away.

Oh, to be a bird! To fly southward to some tropical paradise as winter descends on the Appalachians! But exactly where do our common summer birds go during the winter months? How do they find their way to their winter homes and how do they find their way back?

For thousands of years, bird migration was a mystery to humans. Observers of nature did notice that many birds as well as various other animals disappeared and then reappeared at certain times every year.

Hibernating mammals, reptiles, and amphibians could be located and observed, although with some difficulty, and posed no questions as to their winter location and activity. Similarly, insect grubs could be found in the soil and observed as they metamorphosed into adults in the spring.

But many types of birds seemed to simply vanish in winter. No trace of them was ever found until they suddenly reappeared in spring. Ancient Greeks believed that these birds never really left, they just transmuted into other species each fall and then changed back to their original form in the spring. This was no more amazing to them than the metamorphosis of a caterpillar into a butterfly. As evidence of transmutation they cited the intermediate feather patterns of fall migrants captured as they changed from breeding to nonbreeding plumages.

Aristotle believed that swallows hibernated in knotholes or rock crevasses, curled up in a ball and "quite devoid of feathers." This appears to be a misinterpretation of hibernating bats, which do curl up in such locations and also resemble what a swallow devoid of feathers might look like.

Europeans of the Middle Ages thought swallows spent the winter underwater, in the mud at the bottom of lakes and ponds. This belief was probably fostered by the swallow's habit of flying low over pond surfaces and dipping its bill in order to drink.

The truth about swallows is in i-nany ways stranger still. The Barn Swallow, which is the American equivalent of the European Swallow, leaves the Southern Appalachians each fall and flies as far as Bolivia, Argentina, and northern Chile, where it spends the winter. Is this any easier to believe than transmutation or hibernation "devoid of feathers"?

Many other familiar Appalachian birds are also long distance migrants. The Wood Thrush journeys far to entertain us with its hauntingly beautiful territorial call. Thoreau had this to say about the voice of the Wood Thrush: "Whenever a man hears it he is young, and Nature is in her spring; wherever he hears it, it is a new world and a free country, and the gates of heaven are not shut against him." The Wood Thrush winters in Central America but returns to our southern mountains each spring to sing to us and give our lives meaning.

Another long distance migrant is the Scarlet Tanager. This northeastern most member of the tropical tanager family leaves the forests of Peru and the upper Amazon each spring to ignite our woodlands with the most intensely red plumage of any Appalachian bird.

Wave upon wave of migrating Warblers enliven our wakening mountains each spring. Look for them when Dogwood blossoms are fully extended and new leaves begin to appear on our forest trees. These birds journey from tropical America to dine on leaf-eating insects and to feed them to their young.

Aphids, caterpillars, leafhoppers, and beetles are the reason we have warblers, tanagers, swallows and other migratory birds. Nature seldom wastes food, and insects are a high protein food source which becomes superabundant during each Appalachian spring. Just as caterpillars time their life cycles to emerge with the new leaves, warblers hatch their young at the time of maturing caterpillars.

But just how do warblers navigate from Costa Rica to Roan Mountain, how do Barn Swallows find their way from Argentina to the Asheville basin? Certainly, a high-flying bird can recognize regional landmarks such as mountains and coastlines. But most songbirds migrate at night.

Studies have shown that night migrating birds can find direction from the stars and can also orient themselves by detecting the earth's magnetic field. Even birds raised entirely indoors will align themselves properly to the stars, even the artificial stars of an indoor planetarium, upon seeing them for the first time. Nor is the entire sky necessary; birds can deduce location and bearing if enough sky is visible to reveal a handful of the brighter stars. On completely overcast nights migrating birds must rely on a sense of direction based on magnetism as well as on other cues such as memory, hearing, or even smell!

Warblers and other migrants apparently hatch out of the egg equipped with a star map in their genes, an internal clock, a sense of direction based on the earth's magnetic field, and an intense desire to be at a certain place at a certain time.

The Scarlet Tanager leaves the forests of the upper Amazon each spring, upon raising its young on inchworms and leaf beetles in an Appalachian oak forest. Here the food supply is more abundant and a larger brood may be raised than in the forests of Peru.

Carrying Amazonian fire on its back, the vividly colored migrant unerringly returns each year. Individual tanagers often return to the same mountainside, the same stand of oaks and hickories, the same nesting territory each spring.

Each Scarlet Tanager is an ember of tropical warmth whose presence helps to rekindle the fire of life in our Southern mountains. Each migratory flight spins another strand in the web of life which binds the Appalachians to the Andes, the Mississippi to the Amazon, and all living things to the earth which gave them birth.