Lost Woods: The Discovered Writing of Rachel Carson - Rachel Carson, Linda Lear (1999)

Part I

Chapter 4. Ace of Nature’s Aviators

[1944]

IT WAS TYPICAL of Rachel Carson’s literary craftsmanship and scientific understanding that she could find in the most mundane parts of the natural world some aspect that endowed the familiar with a unique sense of worth, even redemptive value. An early example was a feature article rehabilitating the common starling which first appeared in the Baltimore Sun in early 1939. Carson sold a revised version to Nature Magazine later that same year as “How About Citizenship Papers for the Starling?” It brought favorable comment from readers who were fascinated to learn something of the worthiness of this much maligned bird.

Research that came across Carson’s Fish and Wildlife desk during the war years reinforced her determination to write about scientific topics that would inform the public as well as make the hidden processes of nature understandable to the general reader. “Ace of Nature’s Aviators” reports the discovery of the remarkable migration patterns of the “remote and mysterious” chimney swift. It began as a Department of Interior press release. Having revised it as a feature article, Carson offered it to the Baltimore Sun and to Reader’s Digest, but since she was in need of immediate money following an appendectomy, she hastily sold a condensed version to Coronet which was published as “Sky Dwellers” in November, 1945.

IF AVIATION ENGINEERS could apply the wisdom of the chimney swift, several troublesome problems of aeronautics could be solved. Pilots, for example, would never have to worry about the amount of gasoline in their tanks. The chimney swift refuels on the wing, spends almost its entire waking life in the air, and never, except by accident, touches the earth.

In creating one of her most efficient mechanisms for flight, Nature has fashioned the swift as a flying insect trap. Its beak is short, its mouth one of the widest in birddom. Its torpedo-shaped body and long, slender wings are built for speed and adapted to sudden twists and turns. From dawn till dusk the swift speeds open mouthed through the sky, straining insects out of the air. Although the bird’s aerial existence involves a high rate of fuel consumption, its energy is perpetually renewed by the almost continuous intake of food.

Not only does it eat in the air, the chimney swift drinks and bathes on the wing, dipping to the surface of a pond for a momentary contact with the water; its courtship is aerial; it sometimes even dies in the sky. Probably it is less aware of the earth and its creatures than any other bird in the world. It never perches on a tree, never alights on the ground. Its whole existence is divided between the sky and a nocturnal resting place inside a chimney or a hollow tree.

For its mastery of the air, the swift has paid a strange penalty. Its feet have degenerated into little more than hooks, useless for perching or hopping as other birds do, but perfect for clinging to the wall of a chimney. As a result of its inability to perch, the swift’s idea of going to bed is merely to hang itself up for the night against some vertical surface, its toes securely hooked in a crack or over a convenient projection. Its stubby tail, edged with a row of bristles, provides a useful prop.

The chimney swift is one of the few birds unharmed by the white man’s invasion of North America - it has actually profited by it. Ancestors of the modern chimney swift lived in great hollow trees. When pioneering Americans began to cut down the forests and to build cabins and houses, then churches, schools, and factories, the swifts discovered that a chimney is a first-rate substitute for a hollow tree. Almost to a bird they changed their habits.

In more isolated parts of the country, a few chimney swifts cling to old-fashioned ideas: they still nest in hollow trees. The western cousin of the chimney swift - Vaux’s swift - only of recent years has begun to make the transition from trees to chimneys. So broadminded and so adaptable is the true chimney swift, however, that it has made the most of various other conveniences of civilization, nesting in abandoned buildings, in wells and cisterns, and in silos.

For its intra-chimney architecture the swift is equipped with enormously developed salivary glands. These secrete a thick, gluey saliva useful in fastening twigs together and in cementing the hammocklike nest to the wall of the chimney. The Chinese swift dispenses with twigs, fashions its entire nest of saliva, and so creates the principal ingredient of the delicacy known as bird’s nest soup.

During the nesting season the salivary glands enlarge, providing copious supplies of the needed cement. Later they shrink, but the hollow spaces left in the cheeks of the swift are put to good use - the bird crams them full of insects to bring back to its hungry babies.

Nest building takes two to three weeks, even longer if the days are rainy and the glue melts. Every twig used is collected by an amazing method: the bird snatches them on the wing from trees and shrubbery. To this day ornithologists cannot agree whether it uses feet or beak in the process.

Swifts are devoted parents. The male and female take turns incubating the eggs during the nearly three weeks required for the young to hatch. Thereafter, both birds assume the chore of keeping the infant mouths filled with insects, a task that must be performed faithfully for about four weeks before the young swifts are able to take to the sky in their own behalf.

Unexplained as yet is the fact that observers have sometimes seen three adult birds tending a nest. The polite but wholly tentative theory is that the parents have engaged a “nursemaid.” More realistic persons scoff at that and say the swift is polygamous. What the truth is, no one actually knows.

The chimney swift is rated the fastest small bird in North America and has few natural enemies it needs to fear. Flight records for an Asiatic swift indicate speeds up to 200 miles an hour. It is debatable whether even a duck hawk can overtake one in straight-away flight. An occasional swift, however, may be snatched by a hawk as the birds are circling above a chimney, preparatory to entering for the night.

From one enemy - rain - the bird has no defense. Cold rains, long continued, wash the skies clear of insects. Deprived of food, the swifts weaken and die in great numbers. During one unseasonably wet June reports of dead swifts came from all over southern New England, wheelbarrow loads were taken from the chimneys of large mills, bushels from the base of a chimney at Clark University. Fortunately, such occurrences are comparatively rare.

The life story of the chimney swift has been pieced together by naturalists and amateur birders only with the greatest patience and perseverance. A bird who never perches on a tree where you can focus your binoculars on him, who never visits feeding stations, who spends almost all the daylight hours far above your head, and who, in the fall, vanishes so suddenly and completely that only within the past year has his winter home been discovered - such a bird is not an easy subject for his would-be biographers.

Perhaps because of the very difficulty of the job, an extraordinary number of people seem to have interested themselves in the chimney swift, and have gone to endless trouble to learn its habits. One woman in Iowa had an imitation chimney, equipped with observation tower, built in her back yard so she could study the home life of the swifts that later nested in it. A West Virginia farmer suspended tin coffee cans in his chimney as an invitation to the swifts to nest there. The birds accepted, later permitted the farmer to raise the cans to the top of the chimney at intervals to photograph the young. The ornithologist and artist George Mitsch Sutton, as a young man in West Virginia, repeatedly climbed a tall church chimney and hung for hours, cramped, shivering, and wretched, just below the mouth of the chimney so he could make accurate notes on the wing movements of the swifts as they dropped into the chimney. And all over eastern United States and Canada, people have industriously banded chimney swifts in an effort to trace their migrations, until the total of swifts marked with identifying metal bands now exceeds 375,000.

Banding 375,000 chimney swifts is not as simple as it may seem. If you are one who insists upon lying abed in the chilly dawn or whose experience as a steeple jack is limited, don’t take up swift banding as a hobby. It requires a certain Spartan fortitude. Unlike most birds, the insect-eating swifts cannot be attracted to cage traps baited with grain or other foods. They have to be caught as they emerge at daybreak from the large chimneys where thousands of them sleep, especially near the time of the fall migration.

Swift banders stand about on roofs, shivering as they wait for daylight and the birds. They risk their necks clambering to the tops of tall chimneys to set their traps. They incur the suspicion of the law as they skulk about empty buildings in the small hours. Despite these hazards, Constance and E. A. Everett of Minnesota once wrote cheerfully to an ornithological journal about “the fun of banding chimney swifts.”

A few months ago the banders had their reward. Although many marked swifts had been recaptured, all recoveries had been made within the known summer range of the bird, and the winter home of the swift was still undiscovered. Then to the U.S. headquarters for the study of bird migration, the Fish and Wildlife Service, came a long, official envelope from the American Embassy at Lima, Peru. It contained thirteen bands, taken from chimney swifts shot by Indians in the jungles of Peru during the northern winter. Records showed that the birds had been banded in Tennessee, Illinois, Connecticut, Alabama, Georgia, and Ontario, dates of banding ranging from 1936 to 1940.

For the thirteen small birds, death won ornithological fame. The swift was the last North American bird whose winter range was unknown. The thirteen had now provided the solution of a major mystery of bird migration, had filled in the missing paragraphs in the biography of their race.