Silent Spring
by Rachel Carson
7.
Needless Havoc
AS MAN PROCEEDS toward his announced goal of the conquest of nature, he has
written a depressing record of destruction, directed not only against the earth he inhabits but
against the life that shares it with him. The history of the recent centuries has its black
passages—the slaughter of the buffalo on the western plains, the massacre of the shorebirds by
the market gunners, the near-extermination of the egrets for their plumage. Now, to these and
others like them, we are adding a new chapter and a new kind of havoc—the direct killing of
birds, mammals, fishes, and indeed practically every form of wildlife by chemical insecticides
indiscriminately sprayed on the land. Under the philosophy that now seems to guide our
destinies, nothing must get in the way of the man with the spray gun. The incidental victims of
his crusade against insects count as nothing; if robins, pheasants, raccoons, cats, or even
livestock happen to inhabit the same bit of earth as the target insects and to be hit by the rain
of insect-killing poisons no one must protest.
The citizen who wishes to make a fair judgment of the question of wildlife loss is today
confronted with a dilemma. On the one hand conservationists and many wildlife biologists
assert that the losses have been severe and in some cases even catastrophic. On the other hand
the control agencies tend to deny flatly and categorically that such losses have occurred, or that
they are of any importance if they have. Which view are we to accept? The credibility of the
witness is of first importance. The professional wildlife biologist on the scene is certainly best
qualified to discover and interpret wildlife loss. The entomologist, whose specialty is insects, is
not so qualified by training, and is not psychologically disposed to look for undesirable side
effects of his control program. Yet it is the control men in state and federal governments—and
of course the chemical manufacturers—who steadfastly deny the facts reported by the
biologists and declare they see little evidence of harm to wildlife. Like the priest and the Levite
in the biblical story, they choose to pass by on the other side and to see nothing. Even if we
charitably explain their denials as due to the shortsightedness of the specialist and the man
with an interest this does not mean we must accept them as qualified witnesses.
The best way to form our own judgment is to look at some of the major control programs and
learn, from observers familiar with the ways of wildlife, and unbiased in favor of chemicals, just
what has happened in the wake of a rain of poison falling from the skies into the world of
wildlife. To the bird watcher, the suburbanite who derives joy from birds in his garden, the
hunter, the fisherman or the explorer of wild regions, anything that destroys the wildlife of an
area for even a single year has deprived him of pleasure to which he has a legitimate right. This
is a valid point of view. Even if, as has sometimes happened, some of the birds and mammals
and fishes are able to re-establish themselves after a single spraying, a great and real harm has
been done. But such reestablishment is unlikely to happen. Spraying tends to be repetitive, and
a single exposure from which the wildlife populations might have a chance to recover is a rarity.
What usually results is a poisoned environment, a lethal trap in which not only the resident
populations succumb but those who come in as migrants as well. The larger the area sprayed
the more serious the harm, because no oases of safety remain. Now, in a decade marked by
insect-control programs in which many thousands or even millions of acres are sprayed as a
unit, a decade in which private and community spraying has also surged steadily upward, a
record of destruction and death of American wildlife has accumulated. Let us look at some of
these programs and see what has happened.
During the fall of 1959 some 27,000 acres in southeastern Michigan, including numerous
suburbs of Detroit, were heavily dusted from the air with pellets of aldrin, one of the most
dangerous of all the chlorinated hydrocarbons. The program was conducted by the Michigan
Department of Agriculture with the cooperation of the United States Department of
Agriculture; its announced purpose was control of the Japanese beetle. Little need was shown
for this drastic and dangerous action. On the contrary, Walter P. Nickell, one of the best-known
and best-informed naturalists in the state, who spends much of his time in the field with long
periods in southern Michigan every summer, declared: ‘For more than thirty years, to my direct
knowledge, the Japanese beetle has been present in the city of Detroit in small numbers. The
numbers have not shown any appreciable increase in all this lapse of years. I have yet to see a
single Japanese beetle [in 1959] other than the few caught in Government catch traps in
Detroit...Everything is being kept so secret that I have not yet been able to obtain any
information whatsoever to the effect that they have increased in numbers.’ An official release
by the state agency merely declared that the beetle had ‘put in its appearance’ in the areas
designated for the aerial attack upon it.
Despite the lack of justification the program was
launched, with the state providing the manpower and supervising the operation, the federal
government providing equipment and additional men, and the communities paying for the
insecticide. The Japanese beetle, an insect accidentally imported into the United States, was
discovered in New Jersey in 1916, when a few shiny beetles of a metallic green color were seen
in a nursery near Riverton. The beetles, at first unrecognized, were finally identified as a
common inhabitant of the main islands of Japan. Apparently they had entered the United
States on nursery stock imported before restrictions were established in 1912.
From its original point of entrance the Japanese beetle has spread rather widely throughout
many of the states east of the Mississippi, where conditions of temperature and rainfall are
suitable for it. Each year some outward movement beyond the existing boundaries of its
distribution usually takes place. In the eastern areas where the beetles have been longest
established, attempts have been made to set up natural controls. Where this has been done,
the beetle populations have been kept at relatively low levels, as many records attest. Despite
the record of reasonable control in eastern areas, the midwestern states now on the fringe of
the beetle’s range have launched an attack worthy of the most deadly enemy instead of only a
moderately destructive insect, employing the most dangerous chemicals distributed in a
manner that exposes large numbers of people, their domestic animals, and all wildlife to the
poison intended for the beetle.
As a result these Japanese beetle programs have caused
shocking destruction of animal life and have exposed human beings to undeniable hazard.
Sections of Michigan, Kentucky, Iowa, Indiana, Illinois, and Missouri are all experiencing a rain
of chemicals in the name of beetle control. The Michigan spraying was one of the first large scale attacks on the Japanese beetle from the air. The choice of aldrin, one of the deadliest of
all chemicals, was not determined by any peculiar suitability for Japanese beetle control, but
simply by the wish to save money—aldrin was the cheapest of the compounds available. While
the state in its official release to the press acknowledged that aldrin is a ‘poison’, it implied that
no harm could come to human beings in the heavily populated areas to which the chemical was
applied. (The official answer to the query ‘What precautions should I take?’ was ‘For you,
none.’) An official of the Federal Aviation Agency was later quoted in the local press to the
effect that ‘this is a safe operation’ and a representative of the Detroit Department of Parks and
Recreation added his assurance that ‘the dust is harmless to humans and will not hurt plants or
pets.’ One must assume that none of these officials had consulted the published and readily
available reports of the United States Public Health Service, the Fish and Wildlife Service, and
other evidence of the extremely poisonous nature of aldrin.
Acting under the Michigan pest control law which allows the state to spray indiscriminately
without notifying or gaining permission of individual landowners, the low-lying planes began to
fly over the Detroit area. The city authorities and the Federal Aviation Agency were
immediately besieged by calls from worried citizens. After receiving nearly 800 calls in a single
hour, the police begged radio and television stations and newspapers to ‘tell the watchers what
they were seeing and advise them it was safe,’ according to the Detroit News. The Federal
Aviation Agency’s safety officer assured the public that ‘the planes are carefully supervised’ and
‘are authorized to fly low.’ In a somewhat mistaken attempt to allay fears, he added that the
planes had emergency valves that would allow them to dump their entire load instantaneously.
This, fortunately, was not done, but as the planes went about their work the pellets of
insecticide fell on beetles and humans alike, showers of ‘harmless’ poison descending on
people shopping or going to work and on children out from school for the lunch hour.
Housewives swept the granules from porches and sidewalks, where they are said to have
‘looked like snow’. As pointed out later by the Michigan Audubon Society, ‘In the spaces
between shingles on roofs, in eaves-troughs, in the cracks in bark and twigs, the little white
pellets of aldrin-and-clay, no bigger than a pin head, were lodged by the millions.
When the
snow and rain came, every puddle became a possible death potion.’ Within a few days after the
dusting operation, the Detroit Audubon Society began receiving calls about the birds. According
to the Society’s secretary, Mrs. Ann Boyes, ‘The first indication that the people were concerned
about the spray was a call I received on Sunday morning from a woman who reported that
coming home from church she saw an alarming number of dead and dying birds. The spraying
there had been done on Thursday. She said there were no birds at all flying in the area, that she
had found at least a dozen [dead] in her backyard and that the neighbors had found dead
squirrels.’ All other calls received by Mrs. Boyes that day reported ‘a great many dead birds and
no live ones... People who had maintained bird feeders said there were no birds at all at their
feeders.’ Birds picked up in a dying condition showed the typical symptoms of insecticide
poisoning—tremoring, loss of ability to fly, paralysis, convulsions.
Nor were birds the only forms of life immediately affected. A local veterinarian reported that
his office was full of clients with dogs and cats that had suddenly sickened. Cats, who so
meticulously groom their coats and lick their paws, seemed to be most affected. Their illness
took the form of severe diarrhea, vomiting, and convulsions. The only advice the veterinarian
could give his clients was not to let the animals out unnecessarily, or to wash the paws
promptly if they did so. (But the chlorinated hydrocarbons cannot be washed even from fruits
or vegetables, so little protection could be expected from this measure.)
Despite the insistence of the City-County Health Commissioner that the birds must have been
killed by ‘some other kind of spraying’ and that the outbreak of throat and chest irritations that
followed the exposure to aldrin must have been due to ‘something else’, the local Health
Department received a constant stream of complaints. A prominent Detroit internist was called
upon to treat four of his patients within an hour after they had been exposed while watching
the planes at work. All had similar symptoms: nausea, vomiting, chills, fever, extreme fatigue,
and coughing. The Detroit experience has been repeated in many other communities as
pressure has mounted to combat the Japanese beetle with chemicals. At Blue Island, Illinois,
hundreds of dead and dying birds were picked up. Data collected by birdbanders here suggest
that 80 per cent of the songbirds were sacrificed. In Joliet, Illinois, some 3000 acres were
treated with heptachlor in 1959. According to reports from a local sportsmen’s club, the bird
population within the treated area was ‘virtually wiped out’. Dead rabbits, muskrats, opossums,
and fish were also found in numbers, and one of the local schools made the collection of
insecticide-poisoned birds a science project. . . .
Perhaps no community has suffered more for the sake of a beetle less world than Sheldon, in
eastern Illinois, and adjacent areas in Iroquois County. In 1954 the United States Department of
Agriculture and the Illinois Agriculture Department began a program to eradicate the Japanese
beetle along the line of its advance into Illinois, holding out the hope, and indeed the
assurance, that intensive spraying would destroy the populations of the invading insect. The
first ‘eradication’ took place that year, when dieldrin was applied to 1400 acres by air. Another
2600 acres were treated similarly in 1955, and the task was presumably considered complete.
But more and more chemical treatments were called for, and by the end of 1961 some 131,000
acres had been covered. Even in the first years of the program it was apparent that heavy
losses were occurring among wildlife and domestic animals. The chemical treatments were
continued, nevertheless, without consultation with either the United States Fish and Wildlife
Service or the Illinois Game Management Division. (In the spring of 1960, however, officials of
the federal Department of Agriculture appeared before a congressional committee in
opposition to a bill that would require just such prior consultation. They declared blandly that
the bill was unnecessary because cooperation and consultation were ‘usual’. These officials
were quite unable to recall situations where cooperation had not taken place ‘at the
Washington level’. In the same hearings they stated clearly their unwillingness to consult with
state fish and game departments.) Although funds for chemical control came in never-ending
streams, the biologists of the Illinois Natural History Survey who attempted to measure the
damage to wildlife had to operate on a financial shoestring. A mere $1100 was available for the
employment of a field assistant in 1954 and no special funds were provided in 1955. Despite
these crippling difficulties, the biologists assembled facts that collectively paint a picture of
almost unparalleled wildlife destruction—destruction that became obvious as soon as the
program got under way.
Conditions were made to order for poisoning insect-eating birds, both in the poisons used and
in the events set in motion by their application. In the early programs at Sheldon, dieldrin was
applied at the rate of 3 pounds to the acre. To understand its effect on birds one need only
remember that in laboratory experiments on quail dieldrin has proved to be about 50 times as
poisonous as DDT. The poison spread over the landscape at Sheldon was therefore roughly
equivalent to 150 pounds of DDT per acre! And this was a minimum, because there seems to
have been some overlapping of treatments along field borders and in corners. As the chemical
penetrated the soil the poisoned beetle grubs crawled out on the surface of the ground, where
they remained for some time before they died, attractive to insect-eating birds. Dead and dying
insects of various species were conspicuous for about two weeks after the treatment.
The
effect on the bird populations could easily have been foretold. Brown thrashers, starlings,
meadowlarks, grackles, and pheasants were virtually wiped out. Robins were ‘almost
annihilated’, according to the biologists’ report. Dead earthworms had been seen in numbers
after a gentle rain; probably the robins had fed on the poisoned worms. For other birds, too,
the once beneficial rain had been changed, through the evil power of the poison introduced
into their world, into an agent of destruction. Birds seen drinking and bathing in puddles left by
rain a few days after the spraying were inevitably doomed.
The birds that survived may have been rendered sterile. Although a few nests were found in the
treated area, a few with eggs, none contained young birds. Among the mammals ground
squirrels were virtually annihilated; their bodies were found in attitudes characteristic of violent
death by poisoning. Dead muskrats were found in the treated areas, dead rabbits in the fields.
The fox squirrel had been a relatively common animal in the town; after the spraying it was
gone. It was a rare farm in the Sheldon area that was blessed by the presence of a cat after the
war on beetles was begun. Ninety per cent of all the farm cats fell victims to the dieldrin during
the first season of spraying. This might have been predicted because of the black record of
these poisons in other places. Cats are extremely sensitive to all insecticides and especially so, it
seems, to dieldrin. In western Java in the course of the antimalarial program carried out by the
World Health Organization, many cats are reported to have died. In central Java so many were
killed that the price of a cat more than doubled. Similarly, the World Health Organization,
spraying in Venezuela, is reported to have reduced cats to the status of a rare animal.
In Sheldon it was not only the wild creatures and the domestic companions that were sacrificed
in the campaign against an insect. Observations on several flocks of sheep and a herd of beef
cattle are indicative of the poisoning and death that threatened livestock as well. The Natural
History Survey report describes one of these episodes as follows:
The sheep...were driven into a small, untreated bluegrass pasture across a gravel road from a field which
had been treated with dieldrin spray on May 6. Evidently some spray had drifted across the road into the pasture,
for the sheep began to show symptoms of intoxication almost at once...They lost interest in food and displayed
extreme restlessness, following the pasture fence around and around apparently searching for a way out...They
refused to be driven, bleated almost continuously, and stood with their heads lowered; they were finally carried
from the pasture...They displayed great desire for water. Two of the sheep were found dead in the stream passing
through the pasture, and the remaining sheep were repeatedly driven out of the stream, several having to be
dragged forcibly from the water. Three of the sheep eventually died; those remaining recovered to all outward
appearances.
This, then, was the picture at the end of 1955. Although the chemical war went on in
succeeding years, the trickle of research funds dried up completely. Requests for money for
wildlife-insecticide research were included in annual budgets submitted to the Illinois
legislature by the Natural History Survey, but were invariably among the first items to be
eliminated. It was not until 1960 that money was somehow found to pay the expenses of one
field assistant—to do work that could easily have occupied the time of four men.
The desolate picture of wildlife loss had changed little when the biologists resumed the studies
broken off in 1955. In the meantime, the chemical had been changed to the even more toxic
aldrin, 100 to 300 times as toxic as DDT in tests on quail. By 1960, every species of wild mammal
known to inhabit the area had suffered losses. It was even worse with the birds. In the small
town of Donovan the robins had been wiped out, as had the grackles, starlings, and brown
thrashers. These and many other birds were sharply reduced elsewhere. Pheasant hunters felt
the effects of the beetle campaign sharply. The number of broods produced on treated lands
fell off by some 50 per cent, and the number of young in a brood declined. Pheasant hunting,
which had been good in these areas in former years, was virtually abandoned as unrewarding.
In spite of the enormous havoc that had been wrought in the name of eradicating the Japanese
beetle, the treatment of more than 100,000 acres in Iroquois County over an eight-year period
seems to have resulted in only temporary suppression of the insect, which continues its
westward movement. The full extent of the toll that has been taken by this largely ineffective
program may never be known, for the results measured by the Illinois biologists are a minimum
figure. If the research program had been adequately financed to permit full coverage, the
destruction revealed would have been even more appalling. But in the eight years of the
program, only about $6000 was provided for biological field studies. Meanwhile the federal
government had spent about $375,000 for control work and additional thousands had been
provided by the state. The amount spent for research was therefore a small fraction of 1 per
cent of the outlay for the chemical program.
These midwestern programs have been conducted in a spirit of crisis, as though the advance of
the beetle presented an extreme peril justifying any means to combat it. This of course is a
distortion of the facts, and if the communities that have endured these chemical drenchings
had been familiar with the earlier history of the Japanese beetle in the United States they
would surely have been less acquiescent. The eastern states, which had the good fortune to
sustain their beetle invasion in the days before the synthetic insecticides had been invented,
have not only survived the invasion but have brought the insect under control by means that
represented no threat whatever to other forms of life. There has been nothing comparable to
the Detroit or Sheldon sprayings in the East. The effective methods there involved the bringing
into play of natural forces of control which have the multiple advantages of permanence and
environmental safety. During the first dozen years after its entry into the United States, the
beetle increased rapidly, free of the restraints that in its native land hold it in check. But by
1945 it had become a pest of only minor importance throughout much of the territory over
which it had spread. Its decline was largely a consequence of the importation of parasitic
insects from the Far East and of the establishment of disease organisms fatal to it.
Between 1920 and 1933, as a result of diligent searching throughout the native range of the
beetle, some 34 species of predatory or parasitic insects had been imported from the Orient in
an effort to establish natural control. Of these, five became well established in the eastern
United States. The most effective and widely distributed is a parasitic wasp from Korea and
China, Tiphia vernalis. The female Tiphia, finding a beetle grub in the soil, injects a paralyzing
fluid and attaches a single egg to the undersurface of the grub. The young wasp, hatching as a
larva, feeds on the paralyzed grub and destroys it. In some 25 years, colonies of Tiphia were
introduced into 14 eastern states in a cooperative program of state and federal agencies. The
wasp became widely established in this area and is generally credited by entomologists with an
important role in bringing the beetle under control. An even more important role has been
played by a bacterial disease that affects beetles of the family to which the Japanese beetle
belongs—the scarabaeidae. It is a highly specific organism, attacking no other type of insects,
harmless to earthworms, warm-blooded animals, and plants. The spores of the disease occur in
soil. When ingested by a foraging beetle grub they multiply prodigiously in its blood, causing it
to turn an abnormally white color, hence the popular name, ‘milky disease’.
Milky disease was discovered in New Jersey in 1933. By 1938 it was rather widely prevalent in
the older areas of Japanese beetle infestation. In 1939 a control program was launched,
directed at speeding up the spread of the disease. No method had been developed for growing
the disease organism in an artificial medium, but a satisfactory substitute was evolved; infected
grubs are ground up, dried, and combined with chalk. In the standard mixture a gram of dust
contains 100 million spores. Between 1939 and 1953 some 94,000 acres in 14 eastern states
were treated in a cooperative federal state program; other areas on federal lands were treated;
and an unknown but extensive area was treated by private organizations or individuals. By
1945, milky spore disease was raging among the beetle populations of Connecticut, New York,
New Jersey, Delaware, and Maryland. In some test areas infection of grubs had reached as high
as 94 per cent. The distribution program was discontinued as a governmental enterprise in
1953 and production was taken over by a private laboratory, which continues to supply
individuals, garden clubs, citizens’ associations, and all others interested in beetle control.
The eastern areas where this program was carried out now enjoy a high degree of natural
protection from the beetle. The organism remains viable in the soil for years and therefore
becomes to all intents and purposes permanently established, increasing in effectiveness, and
being continuously spread by natural agencies. Why, then, with this impressive record in the
East, were the same procedures not tried in Illinois and the other mid-western states where the
chemical battle of the beetles is now being waged with such fury?
We are told that inoculation with milky spore disease is ‘too expensive’—although no one
found it so in the 14 eastern states in the 1940s. And by what sort of accounting was the ‘too
expensive’ judgment reached? Certainly not by any that assessed the true costs of the total
destruction wrought by such programs as the Sheldon spraying. This judgment also ignores the
fact that inoculation with the spores need be done only once; the first cost is the only cost. We
are told also that milky spore disease cannot be used on the periphery of the beetle’s range
because it can be established only where a large grub population is already present in the soil.
Like many other statements in support of spraying, this one needs to be questioned. The
bacterium that causes milky spore disease has been found to infect at least 40 other species of
beetles which collectively have quite a wide distribution and would in all probability serve to
establish the disease even where the Japanese beetle population is very small or nonexistent.
Furthermore, because of the long viability of the spores in soil they can be introduced even in
the complete absence of grubs, as on the fringe of the present beetle infestation, there to await
the advancing population.
Those who want immediate results, at whatever cost, will doubtless continue to use chemicals
against the beetle. So will those who favor the modern trend to built-in obsolescence, for
chemical control is self-perpetuating, needing frequent and costly repetition. On the other
hand, those who are willing to wait an extra season or two for full results will turn to milky
disease; they will be rewarded with lasting control that becomes more, rather than less
effective with the passage of time.
An extensive program of research is under way in the United States Department of Agriculture
laboratory at Peoria, Illinois, to find a way to culture the organism of milky disease on an
artificial medium. This will greatly reduce its cost and should encourage its more extensive use.
After years of work, some success has now been reported. When this ‘breakthrough’ is
thoroughly established perhaps some sanity and perspective will be restored to our dealings
with the Japanese beetle, which at the peak of its depredations never justified the nightmare
excesses of some of these Midwestern programs. . . .
Incidents like the eastern Illinois spraying raise a question that is not only scientific but moral.
The question is whether any civilization can wage relentless war on life without destroying
itself, and without losing the right to be called civilized. These insecticides are not selective
poisons; they do not single out the one species of which we desire to be rid. Each of them is
used for the simple reason that it is a deadly poison. It therefore poisons all life with which it
comes in contact: the cat beloved of some family, the farmer’s cattle, the rabbit in the field, and
the horned lark out of the sky. These creatures are innocent of any harm to man. Indeed, by
their very existence they and their fellows make his life more pleasant. Yet he rewards them
with a death that is not only sudden but horrible. Scientific observers at Sheldon described the
symptoms of a meadowlark found near death: ‘Although it lacked muscular coordination and
could not fly or stand, it continued to beat its wings and clutch with its toes while lying on its
side. Its beak was held open and breathing was labored.’ Even more pitiful was the mute
testimony of the dead ground squirrels, which ‘exhibited a characteristic attitude in death. The
back was bowed, and the forelegs with the toes of the feet tightly clenched were drawn close
to the thorax...The head and neck were outstretched and the mouth often contained dirt,
suggesting that the dying animal had been biting at the ground.’
By acquiescing in an act that can cause such suffering to a living creature, who among us is not
diminished as a human being?
8.
And No Birds Sing
OVER INCREASINGLY large areas of the United States, spring now comes unheralded by
the return of the birds, and the early mornings are strangely silent where once they were filled
with the beauty of bird song. This sudden silencing of the song of birds, this obliteration of the
color and beauty and interest they lend to our world have come about swiftly, insidiously, and
unnoticed by those whose communities are as yet unaffected. From the town of Hinsdale,
Illinois, a housewife wrote in despair to one of the world’s leading ornithologists, Robert
Cushman Murphy, Curator Emeritus of Birds at the American Museum of Natural History.
Here in our village the elm trees have been sprayed for several years [she wrote in 1958]. When
we moved here six years ago, there was a wealth of bird life; I put up a feeder and had a steady
stream of cardinals, chickadees, downies and nuthatches all winter, and the cardinals and
chickadees brought their young ones in the summer. After several years of DDT spray, the town
is almost devoid of robins and starlings; chickadees have not been on my shelf for two years,
and this year the cardinals are gone too; the nesting population in the neighborhood seems to
consist of one dove pair and perhaps one catbird family.
It is hard to explain to the children that the birds have been killed off, when they have learned
in school that a Federal law protects the birds from killing or capture. ‘Will they ever come
back?’ they ask, and I do not have the answer. The elms are still dying, and so are the birds. Is
anything being done? Can anything be done? Can I do anything? A year after the federal
government had launched a massive spraying program against the fire ant, an Alabama woman
wrote: ‘Our place has been a veritable bird sanctuary for over half a century. Last July we all
remarked, “There are more birds than ever.” Then, suddenly, in the second week of August,
they all disappeared. I was accustomed to rising early to care for my favorite mare that had a
young filly. There was not a sound of the song of a bird. It was eerie, terrifying. What was man
doing to our perfect and beautiful world?
Finally, five months later a blue jay appeared and a
wren.’ The autumn months to which she referred brought other somber reports from the deep
South, where in Mississippi, Louisiana, and Alabama the Field Notes published quarterly by the
National Audubon Society and the United States Fish and Wildlife Service noted the striking
phenomenon of ‘blank spots weirdly empty of virtually all bird life’. The Field Notes are a
compilation of the reports of seasoned observers who have spent many years afield in their
particular areas and have unparalleled knowledge of the normal bird life of the region. One
such observer reported that in driving about southern Mississippi that fall she saw ‘no land
birds at all for long distances’.
Another in Baton Rouge reported that the contents of her
feeders had lain untouched ‘for weeks on end’, while fruiting shrubs in her yard, that ordinarily
would be stripped clean by that time, still were laden with berries. Still another reported that
his picture window, ‘which often used to frame a scene splashed with the red of 40 or 50
cardinals and crowded with other species, seldom permitted a view of as many as a bird or two
at a time.’
Professor Maurice Brooks of the University of West Virginia, an authority on the
birds of the Appalachian region, reported that the West Virginia bird population had undergone
‘an incredible reduction’. One story might serve as the tragic symbol of the fate of the birds—a
fate that has already overtaken some species, and that threatens all. It is the story of the robin,
the bird known to everyone. To millions of Americans, the season’s first robin means that the
grip of winter is broken. Its coming is an event reported in newspapers and told eagerly at the
breakfast table. And as the number of migrants grows and the first mists of green appear in the
woodlands, thousands of people listen for the first dawn chorus of the robins throbbing in the
early morning light.
But now all is changed, and not even the return of the birds may be taken
for granted. The survival of the robin, and indeed of many other species as well, seems fatefully
linked with the American elm, a tree that is part of the history of thousands of towns from the
Atlantic to the Rockies, gracing their streets and their village squares and college campuses with
majestic archways of green. Now the elms are stricken with a disease that afflicts them
throughout their range, a disease so serious that many experts believe all efforts to save the
elms will in the end be futile. It would be tragic to lose the elms, but it would be doubly tragic if,
in vain efforts to save them, we plunge vast segments of our bird populations into the night of
extinction. Yet this is precisely what is threatened.
The so-called Dutch elm disease entered the
United States from Europe about 1930 in elm burl logs imported for the veneer industry. It is a
fungus disease; the organism invades the water-conducting vessels of the tree, spreads by
spores carried by the flow of sap, and by its poisonous secretions as well as by mechanical
clogging causes the branches to wilt and the tree to die. The disease is spread from diseased to
healthy trees by elm bark beetles. The galleries which the insects have tunneled out under the
bark of dead trees become contaminated with spores of the invading fungus, and the spores
adhere to the insect body and are carried wherever the beetle flies. Efforts to control the
fungus disease of the elms have been directed largely toward control of the carrier insect. In
community after community, especially throughout the strongholds of the American elm, the
Midwest and New England, intensive spraying has become a routine procedure.
What this spraying could mean to bird life, and especially to the robin, was first made clear by
the work of two ornithologists at Michigan State University, Professor George Wallace and one
of his graduate students, John Mehner. When Mr. Mehner began work for the doctorate in
1954, he chose a research project that had to do with robin populations. This was quite by
chance, for at that time no one suspected that the robins were in danger. But even as he
undertook the work, events occurred that were to change its character and indeed to deprive
him of his material. Spraying for Dutch elm disease began in a small way on the university
campus in 1954. The following year the city of East Lansing (where the university is located)
joined in, spraying on the campus was expanded, and, with local programs for gypsy moth and
mosquito control also under way, the rain of chemicals increased to a downpour.
During 1954,
the year of the first light spraying, all seemed well. The following spring the migrating robins
began to return to the campus as usual. Like the bluebells in Tomlinson’s haunting essay ‘The
Lost Wood’, they were ‘expecting no evil’ as they reoccupied their familiar territories. But soon
it became evident that something was wrong. Dead and dying robins began to appear in the
campus. Few birds were seen in their normal foraging activities or assembling in their usual
roosts. Few nests were built; few young appeared. The pattern was repeated with monotonous
regularity in succeeding springs. The sprayed area had become a lethal trap in which each wave
of migrating robins would be eliminated in about a week. Then new arrivals would come in,
only to add to the numbers of doomed birds seen on the campus in the agonized tremors that
precede death. ‘The campus is serving as a graveyard for most of the robins that attempt to
take up residence in the spring,’ said Dr. Wallace. But why?
At first he suspected some disease
of the nervous system, but soon it became evident that ‘in spite of the assurances of the
insecticide people that their sprays were “harmless to birds” the robins were really dying of
insecticidal poisoning; they exhibited the well-known symptoms of loss of balance, followed by
tremors, convulsions, and death.’
Several facts suggested that the robins were being poisoned, not so much by direct contact
with the insecticides as indirectly, by eating earthworms. Campus earthworms had been fed
inadvertently to crayfish in a research project and all the crayfish had promptly died. A snake
kept in a laboratory cage had gone into violent tremors after being fed such worms. And
earthworms are the principal food of robins in the spring. A key piece in the jigsaw puzzle of the
doomed robins was soon to be supplied by Dr. Roy Barker of the Illinois Natural History Survey
at Urbana. Dr. Barker’s work, published in 1958, traced the intricate cycle of events by which
the robins’ fate is linked to the elm trees by way of the earthworms. The trees are sprayed in
the spring (usually at the rate of 2 to 5 pounds of DDT per 50-foot tree, which may be the
equivalent of as much as 23 pounds per acre where elms are numerous) and often again in July,
at about half this concentration.
Powerful sprayers direct a stream of poison to all parts of the
tallest trees, killing directly not only the target organism, the bark beetle, but other insects,
including pollinating species and predatory spiders and beetles. The poison forms a tenacious
film over the leaves and bark. Rains do not wash it away. In the autumn the leaves fall to the
ground, accumulate in sodden layers, and begin the slow process of becoming one with the soil.
In this they are aided by the toil of the earthworms, who feed in the leaf litter, for elm leaves
are among their favorite foods. In feeding on the leaves the worms also swallow the insecticide,
accumulating and concentrating it in their bodies. Dr. Barker found deposits of DDT throughout
the digestive tracts of the worms, their blood vessels, nerves, and body wall. Undoubtedly
some of the earthworms themselves succumb, but others survive to become ‘biological
magnifiers’ of the poison. In the spring the robins return to provide another link in the cycle. As
few as 11 large earthworms can transfer a lethal dose of DDT to a robin. And 11 worms form a
small part of a day’s rations to a bird that eats 10 to 12 earthworms in as many minutes.
Not all robins receive a lethal dose, but another consequence may lead to the extinction of
their kind as surely as fatal poisoning. The shadow of sterility lies over all the bird studies and
indeed lengthens to include all living things within its potential range. There are now only two
or three dozen robins to be found each spring on the entire 185-acre campus of Michigan State
University, compared with a conservatively estimated 370 adults in this area before spraying. In
1954 every robin nest under observation by Mehner produced young. Toward the end of June,
1957, when at least 370 young birds (the normal replacement of the adult population) would
have been foraging over the campus in the years before spraying began, Mehner could find only
one young robin. A year later Dr. Wallace was to report: ‘At no time during the spring or
summer [of 1958] did I see a fledgling robin anywhere on the main campus, and so far I have
failed to find anyone else who has seen one there.’
Part of this failure to produce young is due, of course, to the fact that one or more of a pair of
robins dies before the nesting cycle is completed. But Wallace has significant records which
point to something more sinister—the actual destruction of the birds’ capacity to reproduce.
He has, for example, ‘records of robins and other birds building nests but laying no eggs, and
others laying eggs and incubating them but not hatching them. We have one record of a robin
that sat on its eggs faithfully for 21 days and they did not hatch. The normal incubation period
is 13 days...
Our analyses are showing high concentrations of DDT in the testes and ovaries of
breeding birds,’ he told a congressional committee in 1960. ‘Ten males had amounts ranging
from 30 to 109 parts per million in the testes, and two females had 151 and 211 parts per
million respectively in the egg follicles in their ovaries.’ Soon studies in other areas began to
develop findings equally dismal. Professor Joseph Hickey and his students at the University of
Wisconsin, after careful comparative studies of sprayed and unsprayed areas, reported the
robin mortality to be at least 86 to 88 per cent. The Cranbrook Institute of Science at Bloomfield
Hills, Michigan, in an effort to assess the extent of bird loss caused by the spraying of the elms,
asked in 1956 that all birds thought to be victims of DDT poisoning be turned in to the institute
for examination. The request had a response beyond all expectations. Within a few weeks the
deep-freeze facilities of the institute were taxed to capacity, so that other specimens had to be
refused. By 1959 a thousand poisoned birds from this single community had been turned in or
reported. Although the robin was the chief victim (one woman calling the institute reported 12
robins lying dead on her lawn as she spoke), 63 different species were included among the
specimens examined at the institute. The robins, then, are only one part of the chain of
devastation linked to the spraying of the elms, even as the elm program is only one of the
multitudinous spray programs that cover our land with poisons.
Heavy mortality has occurred
among about 90 species of birds, including those most familiar to suburbanites and amateur
naturalists. The populations of nesting birds in general have declined as much as 90 per cent in
some of the sprayed towns. As we shall see, all the various types of birds are affected—ground
feeders, treetop feeders, bark feeders, predators. It is only reasonable to suppose that all birds
and mammals heavily dependent on earthworms or other soil organisms for food are
threatened by the robins’ fate. Some 45 species of birds include earthworms in their diet.
Among them is the woodcock, a species that winters in southern areas recently heavily sprayed
with heptachlor. Two significant discoveries have now been made about the woodcock.
Production of young birds on the New Brunswick breeding grounds is definitely reduced, and
adult birds that have been analyzed contain large residues of DDT and heptachlor.
Already
there are disturbing records of heavy mortality among more than 20 other species of ground feeding birds whose food—worms, ants, grubs, or other soil organisms—has been poisoned.
These include three of the thrushes whose songs are among the most exquisite of bird voices,
the olive-backed, the wood, and the hermit. And the sparrows that flit through the shrubby
understory of the woodlands and forage with rustling sounds amid the fallen leaves—the song
sparrow and the white-throat—these, too, have been found among the victims of the elm
sprays. Mammals, also, may easily be involved in the cycle, directly or indirectly. Earthworms
are important among the various foods of the raccoon, and are eaten in the spring and fall by
opossums. Such subterranean tunnelers as shrews and moles capture them in numbers, and
then perhaps pass on the poison to predators such as screech owls and barn owls.
Several dying screech owls were picked up in Wisconsin following heavy rains in spring, perhaps
poisoned by feeding on earthworms. Hawks and owls have been found in convulsions—great
horned owls, screech owls, red-shouldered hawks, sparrow hawks, marsh hawks. These may be
cases of secondary poisoning, caused by eating birds or mice that have accumulated
insecticides in their livers or other organs. Nor is it only the creatures that forage on the ground
or those who prey on them that are endangered by the foliar spraying of the elms. All of the
treetop feeders, the birds that glean their insect food from the leaves, have disappeared from
heavily sprayed areas, among them those woodland sprites the kinglets, both ruby-crowned
and golden-crowned, the tiny gnatcatchers, and many of the warblers, whose migrating hordes
flow through the trees in spring in a multicolored tide of life.
In 1956, a late spring delayed
spraying so that it coincided with the arrival of an exceptionally heavy wave of warbler
migration. Nearly all species of warblers present in the area were represented in the heavy kill
that followed. In Whitefish Bay, Wisconsin, at least a thousand myrtle warblers could be seen in
migration during former years; in 1958, after the spraying of the elms, observers could find only
two. So, with additions from other communities, the list grows, and the warblers killed by the
spray include those that most charm and fascinate all who are aware of them: the black-and white, the yellow, the magnolia, and the Cape May; the ovenbird, whose call throbs in the
Maytime woods; the Blackburnian, whose wings are touched with flame; the chestnut-sided,
the Canadian, and the black-throated green. These treetop feeders are affected either directly
by eating poisoned insects or indirectly by a shortage of food.
The loss of food has also struck hard at the swallows that cruise the skies, straining out the
aerial insects as herring strain the plankton of the sea. A Wisconsin naturalist reported:
‘Swallows have been hard hit. Everyone complains of how few they have compared to four or
five years ago. Our sky overhead was full of them only four years ago. Now we seldom see
any...This could be both lack of insects because of spray, or poisoned insects.’ Of other birds
this same observer wrote: ‘Another striking loss is the phoebe. Flycatchers are scarce
everywhere but the early hardy common phoebe is no more. I’ve seen one this spring and only
one last spring. Other birders in Wisconsin make the same complaint. I have had five or six pair
of cardinals in the past, none now. Wrens, robins, catbirds and screech owls have nested each
year in our garden. There are none now. Summer mornings are without bird song. Only pest
birds, pigeons, starlings and English sparrows remain. It is tragic and I can’t bear it.’
The dormant sprays applied to the elms in the fall, sending the poison into every little crevice in
the bark, are probably responsible for the severe reduction observed in the number of
chickadees, nuthatches, titmice, woodpeckers, and brown creepers. During the winter of 1957-
58, Dr. Wallace saw no chickadees or nuthatches at his home feeding station for the first time
in many years. Three nuthatches he found later provided a sorry little step-by-step lesson in
cause and effect: one was feeding on an elm, another was found dying of typical DDT
symptoms, the third was dead. The dying nuthatch was later found to have 226 parts per
million of DDT in its tissues. The feeding habits of all these birds not only make them especially
vulnerable to insect sprays but also make their loss a deplorable one for economic as well as
less tangible reasons. The summer food of the white-breasted nuthatch and the brown creeper,
for example, includes the eggs, larvae, and adults of a very large number of insects injurious to
trees. About three quarters of the food of the chickadee is animal, including all stages of the life
cycle of many insects. The chickadee’s method of feeding is described in Bent’s monumental
Life Histories of North American birds: ‘As the flock moves along each bird examines minutely
bark, twigs, and branches, searching for tiny bits of food (spiders’ eggs, cocoons, or other
dormant insect life).’ Various scientific studies have established the critical role of birds in insect
control in various situations. Thus, woodpeckers are the primary control of the Engelmann
spruce beetle, reducing its populations from 45 to 98 per cent and are important in the control
of the codling moth in apple orchards. Chickadees and other winter-resident birds can protect
orchards against the cankerworm.
But what happens in nature is not allowed to happen in the modern, chemical-drenched world,
where spraying destroys not only the insects but their principal enemy, the birds. When later
there is a resurgence of the insect population, as almost always happens, the birds are not
there to keep their numbers in check. As the Curator of Birds at the Milwaukee Public Museum,
Owen J. Gromme, wrote to the Milwaukee Journal:
‘The greatest enemy of insect life is other
predatory insects, birds, and some small mammals, but DDT kills indiscriminately, including
nature’s own safeguards or policemen... In the name of progress are we to become victims of
our own diabolical means of insect control to provide temporary comfort, only to lose out to
destroying insects later on? By what means will we control new pests, which will attack
remaining tree species after the elms are gone, when nature’s safeguards (the birds) have been
wiped out by poison?’
Mr. Gromme reported that calls and letters about dead and dying birds had been increasing
steadily during the years since spraying began in Wisconsin. Questioning always revealed that
spraying or fogging had been done in the area where the birds were dying.
Mr. Gromme’s experience has been shared by ornithologists and conservationists at most of
the research centers of the Midwest such as the Cranbrook Institute in Michigan, the Illinois
Natural History Survey, and the University of Wisconsin. A glance at the Letters-from-Readers
column of newspapers almost anywhere that spraying is being done makes clear the fact that
citizens are not only becoming aroused and indignant but that often they show a keener
understanding of the dangers and inconsistencies of spraying than do the officials who order it
done. ‘I am dreading the days to come soon now when many beautiful birds will be dying in our
back yard,’ wrote a Milwaukee woman. ‘This is a pitiful, heartbreaking experience... It is,
moreover, frustrating and exasperating, for it evidently does not serve the purpose this
slaughter was intended to serve... Taking a long look, can you save trees without also saving
birds? Do they not, in the economy of nature, save each other? Isn’t it possible to help the
balance of nature without destroying it?’
The idea that the elms, majestic shade trees though
they are, are not ‘sacred cows’ and do not justify an ‘open end’ campaign of destruction against
all other forms of life is expressed in other letters.
‘I have always loved our elm trees which
seemed like trademarks on our landscape,’ wrote another Wisconsin woman. ‘But there are
many kinds of trees...We must save our birds, too. Can anyone imagine anything so cheerless
and dreary as a springtime without a robin’s song?’
To the public the choice may easily appear
to be one of stark black-or-white simplicity: Shall we have birds or shall we have elms? But it is
not as simple as that, and by one of the ironies that abound throughout the field of chemical
control we may very well end by having neither if we continue on our present, well-traveled
road. Spraying is killing the birds but it is not saving the elms. The illusion that salvation of the
elms lies at the end of a spray nozzle is a dangerous will-o’- the-wisp that is leading one
community after another into a morass of heavy expenditures, without producing lasting
results.
Greenwich, Connecticut sprayed regularly for ten years. Then a drought year brought
conditions especially favorable to the beetle and the mortality of elms went up 1000 per cent.
In Urbana, Illinois, where the University of Illinois is located, Dutch elm disease first appeared in
1951. Spraying was undertaken in 1953. By 1959, in spite of six years’ spraying, the university
campus had lost 86 per cent of its elms, half of them victims of Dutch elm disease. In Toledo,
Ohio, a similar experience caused the Superintendent of Forestry, Joseph A. Sweeney, to take a
realistic look at the results of spraying.
Spraying was begun there in 1953 and continued
through 1959. Meanwhile, however, Mr. Sweeney had noticed that a city-wide infestation of
the cottony maple scale was worse after the spraying recommended by ‘the books and the
authorities’ than it had been before. He decided to review the results of spraying for Dutch elm
disease for himself. His findings shocked him. In the city of Toledo, he found, ‘the only areas
under any control were the areas where we used some promptness in removing the diseased or
brood trees. Where we depended on spraying the disease was out of control.
In the country
where nothing has been done the disease has not spread as fast as it has in the city. This
indicates that spraying destroys any natural enemies. ‘We are abandoning spraying for the
Dutch elm disease. This has brought me into conflict with the people who back any
recommendations by the United States Department of Agriculture but I have the facts and will
stick with them.’ It is difficult to understand why these midwestern towns, to which the elm
disease spread only rather recently, have so unquestioningly embarked on ambitious and
expensive spraying programs, apparently without waiting to inquire into the experience of
other areas that have had longer acquaintance with the problem.
New York State, for example,
has certainly had the longest history of continuous experience with Dutch elm disease, for it
was via the Port of New York that diseased elm wood is thought to have entered the United
States about 1930. And New York State today has a most impressive record of containing and
suppressing the disease. Yet it has not relied upon spraying. In fact, its agricultural extension
service does not recommend spraying as a community method of control.
How, then, has New York achieved its fine record? From the early years of the battle for the
elms to the present time, it has relied upon rigorous sanitation, or the prompt removal and
destruction of all diseased or infected wood. In the beginning some of the results were
disappointing, but this was because it was not at first understood that not only diseased trees
but all elm wood in which the beetles might breed must be destroyed. Infected elm wood, after
being cut and stored for firewood, will release a crop of fungus-carrying beetles unless burned
before spring. It is the adult beetles, emerging from hibernation to feed in late April and May,
that transmit Dutch elm disease. New York entomologists have learned by experience what
kinds of beetle-breeding material have real importance in the spread of the disease. By
concentrating on this dangerous material, it has been possible not only to get good results, but
to keep the cost of the sanitation program within reasonable limits. By 1950 the incidence of
Dutch elm disease in New York City had been reduced to of 1 per cent of the city’s 55,000 elms.
A sanitation program was launched in Westchester County in 1942.
During the next 14 years the average annual loss of elms was only of 1 per cent a year. Buffalo,
with 185,000 elms, has an excellent record of containing the disease by sanitation, with recent
annual losses amounting to only of 1 per cent. In other words, at this rate of loss it would take
about 300 years to eliminate Buffalo’s elms. What has happened in Syracuse is especially
impressive. There no effective program was in operation before 1957. Between 1951 and 1956
Syracuse lost nearly 3000 elms. Then, under the direction of Howard C. Miller of the New York
State University College of Forestry, an intensive drive was made to remove all diseased elm
trees and all possible sources of beetle-breeding elm wood. The rate of loss is now well below 1
per cent a year. The economy of the sanitation method is stressed by New York experts in
Dutch elm disease control.
‘In most cases the actual expense is small compared with the
probable saving,’ says J. G. Matthysse of the New York State College of Agriculture.‘If it is a
case of a dead or broken limb, the limb would have to be removed eventually, as a precaution
against possible property damage or personal injury. If it is a fuel-wood pile, the wood can be
used before spring, the bark can be peeled from the wood, or the wood can be stored in a dry
place. In the case of dying or dead elm trees, the expense of prompt removal to prevent Dutch
elm disease spread is usually no greater than would be necessary later, for most dead trees in
urban regions must be removed eventually.’
The situation with regard to Dutch elm disease is
therefore not entirely hopeless provided informed and intelligent measures are taken. While it
cannot be eradicated by any means now known, once it has become established in a
community, it can be suppressed and contained within reasonable bounds by sanitation, and
without the use of methods that are not only futile but involve tragic destruction of bird life.
Other possibilities lie within the field of forest genetics, where experiments offer hope of
developing a hybrid elm resistant to Dutch elm disease. The European elm is highly resistant,
and many of them have been planted in Washington, D.C. Even during a period when a high
percentage of the city’s elms were affected, no cases of Dutch elm disease were found among
these trees. Replanting through an immediate tree nursery and forestry program is being urged
in communities that are losing large numbers of elms. This is important, and although such
programs might well include the resistant European elms, they should aim at a variety of
species so that no future epidemic could deprive a community of its trees. The key to a healthy
plant or animal community lies in what the British ecologist Charles Elton calls ‘the conservation
of variety’. What is happening now is in large part a result of the biological unsophistication of
past generations. Even a generation ago no one knew that to fill large areas with a single
species of tree was to invite disaster. And so whole towns lined their streets and dotted their
parks with elms, and today the elms die and so do the birds. . . .
Like the robin, another American bird seems to be on the verge of extinction. This is the
national symbol, the eagle. Its populations have dwindled alarmingly within the past decade.
The facts suggest that something is at work in the eagle’s environment which has virtually
destroyed its ability to reproduce. What this may be is not yet definitely known, but there is
some evidence that insecticides are responsible.
The most intensively studied eagles in North America have been those nesting along a stretch
of coast from Tampa to Fort Myers on the western coast of Florida. There a retired banker from
Winnipeg, Charles Broley, achieved ornithological fame by banding more than 1,000 young bald
eagles during the years 1939-49. (Only 166 eagles had been banded in all the earlier history of
bird banding.) Mr. Broley banded eagles as young birds during the winter months before they
had left their nests. Later recoveries of banded birds showed that these Florida-born eagles
range northward along the coast into Canada as far as Prince Edward Island, although they had
previously been considered nonmigratory. In the fall they return to the South, their migration
being observed at such famous vantage points as Hawk Mountain in eastern Pennsylvania.
During the early years of his banding, Mr. Broley used to find 125 active nests a year on the
stretch of coast he had chosen for his work. The number of young banded each year was about
150. In 1947 the production of young birds began to decline. Some nests contained no eggs;
others contained eggs that failed to hatch. Between 1952 and 1957, about 80 per cent of the
nests failed to produce young. In the last year of this period only 43 nests were occupied. Seven
of them produced young (8 eaglets); 23 contained eggs that failed to hatch; 13 were used
merely as feeding stations by adult eagles and contained no eggs.
In 1958 Mr. Broley ranged
over 100 miles of coast before finding and banding one eaglet. Adult eagles, which had been
seen at 43 nests in 1957, were so scarce that he observed them at only 10 nests. Although Mr.
Broley’s death in 1959 terminated this valuable series of uninterrupted observations, reports by
the Florida Audubon Society, as well as from New Jersey and Pennsylvania, confirm the trend
that may well make it necessary for us to find a new national emblem.
The reports of Maurice
Broun, curator of the Hawk Mountain Sanctuary, are especially significant. Hawk Mountain is a
picturesque mountaintop in southeastern Pennsylvania, where the easternmost ridges of the
Appalachians form a last barrier to the westerly winds before dropping away toward the coastal
plain. Winds striking the mountains are deflected upward so that on many autumn days there is
a continuous updraft on which the broad-winged hawks and eagles ride without effort, covering
many miles of their southward migration in a day. At Hawk Mountain the ridges converge and
so do the aerial highways. The result is that from a widespread territory to the north birds pass
through this traffic bottleneck.
In his more than a score of years as custodian of the sanctuary
there, Maurice Broun has observed and actually tabulated more hawks and eagles than any
other American. The peak of the bald eagle migration comes in late August and early
September. These are assumed to be Florida birds, returning to home territory after a summer
in the North. (Later in the fall and early winter a few larger eagles drift through. These are
thought to belong to a northern race, bound for an unknown wintering ground.) During the first
years after the sanctuary was established, from 1935 to 1939, 40 per cent of the eagles
observed were yearlings, easily identified by their uniformly dark plumage. But in recent years
these immature birds have become a rarity.
Between 1955 and 1959, they made up only 20 per
cent of the total count, and in one year (1957) there was only one young eagle for every 32
adults. Observations at Hawk Mountain are in line with findings elsewhere. One such report
comes from Elton Fawks, an official of the Natural Resources Council of Illinois. Eagles—
probably northern nesters—winter along the Mississippi and Illinois Rivers. In 1958 Mr. Fawks
reported that a recent count of 59 eagles had included only one immature bird. Similar
indications of the dying out of the race come from the world’s only sanctuary for eagles alone,
Mount Johnson Island in the Susquehanna River. The island, although only 8 miles above
Conowingo Dam and about half a mile out from the Lancaster County shore, retains its
primitive wildness.
Since 1934 its single eagle nest has been under observation by Professor
Herbert H. Beck, an ornithologist of Lancaster and custodian of the sanctuary. Between 1935
and 1947 use of the nest was regular and uniformly successful. Since 1947, although the adults
have occupied the nest and there is evidence of egg laying, no young eagles have been
produced. On Mount Johnson Island as well as in Florida, then, the same situation prevails—
there is some occupancy of nests by adults, some production of eggs, but few or no young
birds. In seeking an explanation, only one appears to fit all the facts. This is that the
reproductive capacity of the birds has been so lowered by some environmental agent that
there are now almost no annual additions of young to maintain the race.
Exactly this sort of situation has been produced artificially in other birds by various
experimenters, notably Dr. James DeWitt of the United States Fish and Wildlife Service. Dr.
DeWitt’s now classic experiments on the effect of a series of insecticides on quail and
pheasants have established the fact that exposure to DDT or related chemicals, even when
doing no observable harm to the parent birds, may seriously affect reproduction. The way the
effect is exerted may vary, but the end result is always the same.
For example, quail into whose
diet DDT was introduced throughout the breeding season survived and even produced normal
numbers of fertile eggs. But few of the eggs hatched. ‘Many embryos appeared to develop
normally during the early stages of incubation, but died during the hatching period,’ Dr. DeWitt
said. Of those that did hatch, more than half died within 5 days. In other tests in which both
pheasants and quail were the subjects, the adults produced no eggs whatever if they had been
fed insecticide-contaminated diets throughout the year.
And at the University of California, Dr.
Robert Rudd and Dr. Richard Genelly reported similar findings. When pheasants received
dieldrin in their diets, ‘egg production was markedly lowered and chick survival was poor.’
According to these authors, the delayed but lethal effect on the young birds follows from
storage of dieldrin in the yolk of the egg, from which it is gradually assimilated during
incubation and after hatching. This suggestion is strongly supported by recent studies by Dr.
Wallace and a graduate student, Richard F. Bernard, who found high concentrations of DDT in
robins on the Michigan State University campus.
They found the poison in all of the testes of
male robins examined, in developing egg follicles, in the ovaries of females, in completed but
unlaid eggs, in the oviducts, in unhatched eggs from deserted nests, in embryos within the eggs,
and in a newly hatched, dead nestling. These important studies establish the fact that the
insecticidal poison affects a generation once removed from initial contact with it. Storage of
poison in the egg, in the yolk material that nourishes the developing embryo, is a virtual death
warrant and explains why so many of DeWitt’s birds died in the egg or a few days after
hatching.
Laboratory application of these studies to eagles presents difficulties that are nearly
insuperable, but field studies are now under way in Florida, New Jersey, and elsewhere in the
hope of acquiring definite evidence as to what has caused the apparent sterility of much of the
eagle population. Meanwhile, the available circumstantial evidence points to insecticides. In
localities where fish are abundant they make up a large part of the eagle’s diet (about 65 per
cent in Alaska; about 52 per cent in the Chesapeake Bay area). Almost unquestionably the
eagles so long studied by Mr. Broley were predominantly fish eaters. Since 1945 this particular
coastal area has been subjected to repeated sprayings with DDT dissolved in fuel oil.
The
principal target of the aerial spraying was the salt-marsh mosquito, which inhabits the marshes
and coastal areas that are typical foraging areas for the eagles. Fishes and crabs were killed in
enormous numbers. Laboratory analyses of their tissues revealed high concentrations of DDT—
as much as 46 parts per million. Like the grebes of Clear Lake, which accumulated heavy
concentrations of insecticide residues from eating the fish of the lake, the eagles have almost
certainly been storing up the DDT in the tissues of their bodies. And like the grebes, the
pheasants, the quail, and the robins, they are less and less able to produce young and to
preserve the continuity of their race. . . .
From all over the world come echoes of the peril that faces birds in our modern world. The
reports differ in detail, but always repeat the theme of death to wildlife in the wake of
pesticides. Such are the stories of hundreds of small birds and partridges dying in France after
vine stumps were treated with an arsenic-containing herbicide, or of partridge shoots in
Belgium, once famous for the numbers of their birds, denuded of partridges after the spraying
of nearby farmlands. In England the major problem seems to be a specialized one, linked with
the growing practice of treating seed with insecticides before sowing. Seed treatment is not a
wholly new thing, but in earlier years the chemicals principally used were fungicides. No effects
on birds seem to have been noticed. Then about 1956 there was a change to dual-purpose treatment; in addition to a fungicide, dieldrin, aldrin, or heptachlor was added to combat soil
insects. Thereupon the situation changed for the worse.
In the spring of 1960 a deluge of reports of dead birds reached British wildlife authorities,
including the British Trust for Ornithology, the Royal Society for the Protection of Birds, and the
Game Birds Association.
‘The place is like a battlefield,’ a landowner in Norfolk wrote. ‘My
keeper has found innumerable corpses, including masses of small birds— Chaffinches,
Greenfinches, Linnets, Hedge Sparrows, also House Sparrows...the destruction of wild life is
quite pitiful.’
A gamekeeper wrote: ‘My Partridges have been wiped out with the dressed corn,
also some Pheasants and all other birds, hundreds of birds have been killed... As a lifelong
gamekeeper it has been a distressing experience for me. It is bad to see pairs of Partridges that
have died together.’
In a joint report, the British Trust for Ornithology and the Royal Society for
the Protection of Birds described some 67 kills of birds—a far from complete listing of the
destruction that took place in the spring of 1960. Of these 67, 59 were caused by seed
dressings, 8 by toxic sprays. A new wave of poisoning set in the following year. The death of 600
birds on a single estate in Norfolk was reported to the House of Lords, and 100 pheasants died
on a farm in North Essex. It soon became evident that more counties were involved than in
1960 (34 compared with 23). Lincolnshire, heavily agricultural, seemed to have suffered most,
with reports of 10,000 birds dead. But destruction involved all of agricultural England, from
Angus in the north to Cornwall in the south, from Anglesey in the west to Norfolk in the east.
In the spring of 1961 concern reached such a peak that a special committee of the House of
Commons made an investigation of the matter, taking testimony from farmers, landowners,
and representatives of the Ministry of Agriculture and of various governmental and nongovernmental agencies concerned with wildlife. ‘Pigeons are suddenly dropping out of the sky
dead,’ said one witness. ‘You can drive a hundred or two hundred miles outside London and not
see a single kestrel,’ reported another. ‘There has been no parallel in the present century, or at
any time so far as I am aware, [this is] the biggest risk to wildlife and game that ever occurred in
the country,’ officials of the Nature Conservancy testified.
Facilities for chemical analysis of the victims were most inadequate to the task, with only two
chemists in the country able to make the tests (one the government chemist, the other in the
employ of the Royal Society for the Protection of Birds). Witnesses described huge bonfires on
which the bodies of the birds were burned. But efforts were made to have carcasses collected
for examination, and of the birds analyzed, all but one contained pesticide residues. The single
exception was a snipe, which is not a seed-eating bird. Along with the birds, foxes also may
have been affected, probably indirectly by eating poisoned mice or birds. England, plagued by
rabbits, sorely needs the fox as a predator. But between November 1959 and April 1960 at least
1300 foxes died. Deaths were heaviest in the same counties from which sparrow hawks,
kestrels, and other birds of prey virtually disappeared, suggesting that the poison was spreading
through the food chain, reaching out from the seed eaters to the furred and feathered
carnivores. The actions of the moribund foxes were those of animals poisoned by chlorinated
hydrocarbon insecticides. They were seen wandering in circles, dazed and half blind, before
dying in convulsions.
The hearings convinced the committee that the threat to wildlife was ‘most alarming’; it
accordingly recommended to the House of Commons that ‘the Minister of Agriculture and the
Secretary of State for Scotland should secure the immediate prohibition for the use as seed
dressings of compounds containing dieldrin, aldrin, or heptachlor, or chemicals of comparable
toxicity.’ The committee also recommended more adequate controls to ensure that chemicals
were adequately tested under field as well as laboratory conditions before being put on the
market. This, it is worth emphasizing, is one of the great blank spots in pesticide research
everywhere. Manufacturers’ tests on the common laboratory animals—rats, dogs, guinea
pigs—include no wild species, no birds as a rule, no fishes, and are conducted under controlled
and artificial conditions.
Their application to wildlife in the field is anything but precise. England
is by no means alone in its problem of protecting birds from treated seeds. Here in the United
States the problem has been most troublesome in the rice-growing areas of California and the
South. For a number of years California rice growers have been treating seed with DDT as
protection against tadpole shrimp and scavenger beetles which sometimes damage seedling
rice. California sportsmen have enjoyed excellent hunting because of the concentrations of
waterfowl and pheasants in the rice fields.
But for the past decade persistent reports of bird
losses, especially among pheasants, ducks, and blackbirds, have come from the rice-growing
counties. ‘Pheasant sickness’ became a well-known phenomenon: birds ‘seek water, become
paralyzed, and are found on the ditch banks and rice checks quivering,’ according to one
observer. The ‘sickness’ comes in the spring, at the time the rice fields are seeded. The
concentration of DDT used is many times the amount that will kill an adult pheasant.
The passage of a few years and the development of even more poisonous insecticides served to
increase the hazard from treated seed. Aldrin, which is 100 times as toxic as DDT to pheasants,
is now widely used as a seed coating. In the rice fields of eastern Texas, this practice has
seriously reduced the populations of the famous tree duck, a tawny-colored, goose like duck of
the Gulf Coast. Indeed, there is some reason to think that the rice growers, having found a way
to reduce the populations of blackbirds, are using the insecticide for a dual purpose, with
disastrous effects on several bird species of the rice fields. As the habit of killing grows—the
resort to ‘eradicating’ any creature that may annoy or inconvenience us—birds are more and
more finding themselves a direct target of poisons rather than an incidental one.
There is a
growing trend toward aerial applications of such deadly poisons as parathion to ‘control’
concentrations of birds distasteful to farmers. The Fish and Wildlife Service has found it
necessary to express serious concern over this trend, pointing out that ‘parathion treated areas
constitute a potential hazard to humans, domestic animals, and wildlife.’ In southern Indiana,
for example, a group of farmers went together in the summer of 1959 to engage a spray plane
to treat an area of river bottomland with parathion. The area was a favored roosting site for
thousands of blackbirds that were feeding in nearby corn fields. The problem could have been
solved easily by a slight change in agricultural practice shift to a variety of corn with deep-set
ears not accessible to the birds—but the farmers had been persuaded of the merits of killing by
poison, and so they sent in the planes on their mission of death.
The results probably gratified the farmers, for the casualty list included some 65,000 red winged blackbirds and starlings. What other wildlife deaths may have gone unnoticed and
unrecorded is not known. Parathion is not a specific for blackbirds: it is a universal killer. But
such rabbits or raccoons or opossums as may have roamed those bottomlands and perhaps
never visited the farmers’ cornfields were doomed by a judge and jury who neither knew of
their existence nor cared.
And what of human beings? In California orchards sprayed with this
same parathion, workers handling foliage that had been treated a month earlier collapsed and
went into shock, and escaped death only through skilled medical attention.
Does Indiana still raise any boys who roam through woods or fields and might even explore the
margins of a river? If so, who guarded the poisoned area to keep out any who might wander in,
in misguided search for unspoiled nature?
Who kept vigilant watch to tell the innocent stroller
that the fields he was about to enter were deadly—all their vegetation coated with a lethal
film? Yet at so fearful a risk the farmers, with none to hinder them, waged their needless war
on blackbirds. In each of these situations, one turns away to ponder the question: Who has
made the decision that sets in motion these chains of poisonings, this ever-widening wave of
death that spreads out, like ripples when a pebble is dropped into a still pond? Who has placed
in one pan of the scales the leaves that might have been eaten by the beetles and in the other
the pitiful heaps of many-hued feathers, the lifeless remains of the birds that fell before the
unselective bludgeon of insecticidal poisons?
Who has decided —who has the right to decide—
for the countless legions of people who were not consulted that the supreme value is a world
without insects, even though it be also a sterile world un-graced by the curving wing of a bird in
flight? The decision is that of the authoritarian temporarily entrusted with power; he has made
it during a moment of inattention by millions to whom beauty and the ordered world of nature
still have a meaning that is deep and imperative.
next-73s
9. Rivers of Death
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