Modern Pesticides Aren't Killing Birds
An Ambitious Autopsy Program In New York Finds That Modern Pesticides Aren't The Culprit In Bird Deaths
December 12, 2000
by Dennis T. Avery
THE BridgeNews FORUM: Viewpoints on farming, farm policy and related agricultural issues, December 1, 2000.
CHURCHVILLE, Va.--New evidence from New York state shows that modern pesticides aren't killing off our bird populations.
The fear of West Nile virus, which is spread by birds has lately energized New Yorkers to collect every dead bird carcass they find and send it to the State for autopsy.
The state's wildlife pathology laboratory has already autopsied more than 9,000 dead birds this year, along with 1,000 other mammals and amphibians submitted from all over the state.
The result has been a vast new database on wildlife deaths. "Relatively few animals died from accidental pesticide exposure," reports the laboratory director, Ward B. Stone. "Most of the small number of birds that were killed by manufactured poisons....either ingested a chemical that is no longer in use but is still in the ecosystem (like chlordane) or ate poison deliberately set out by humans."
"The great specter that has haunted the naturalist-environmental movement since at least the 1960s, when Rachel Carson published her polemic against agricultural toxins, "Silent Spring", is waning," says Stone.
Ever since "Silent Spring" was published in 1962, bird lovers all over the world have assumed that pesticides take a huge toll of birds in farming and suburban areas.
David Pimentel of New York's Cornell University asserted in 1992 that U.S. farmers kill 67 million wild birds annually with pesticide applications.
There has been little evidence of such huge bird losses, said Pimentel, because "bird carcasses disappear quickly due to invertebrate scavengers, and field studies seldom account for birds that die a distance from treated areas."
The New York wildlife autopsies make activists like Pimentel sound like scaremongers. Even the New York Times, which has been carrying forward Carson's campaign against pesticides for decades, noted the relatively few wildlife poisonings from properly used pesticides in a November 27 article about the lab's findings.
What does kill the birds? The answer seems to be a wide variety of causes, ranging from fatal fungi and gastrointestinal tapeworms to an epidemic of protozoan parasites that is killing New York mourning doves.
Loons have been washing up recently on the shores of Lake Erie, killed by botulism.
Stone thinks heavy rains flushed local sewage systems into the lake, with the toxins passing into the tissues of zebra mussels and fish and then up the food chain into the birds.
Stone says the newer rat poisons, which are capable of killing rats in a single feeding, are also capable of killing owls and red-tailed hawks that eat poisoned rats. (Since rats can be major disease vectors, Stone hopes for a safer and equally effective rat poison.)
Stone found that a flock of dead gulls near a landfill in Cortland, N.Y., had eaten poisoned bread, apparently put out by an annoyed neighbor of the landfill. The label on the pesticide diazinon warns it's highly toxic to birds, and Stone suspects some people buy it deliberately to get rid of nuisance birds.
Douglas Roscoe of the New Jersey Division of Fish and Wildlife says that most of the chlordane poisonings are from a relatively few lawns and golf courses treated decades ago in an effort to control turf grubs and beetles, before the chemical was banned.
Overall, current First World lifestyles are pretty favorable for birds. Bird expert Roger Tory Peterson estimated that America has as many as 2 billion more songbirds than the Pilgrims found in the 17th century, because farms and suburbs have created more "forest edge." (Old-growth forests provide an unfavorable environment for most birds because they produce little food.)
First World families don't hunt birds for food on a daily basis. Modern fishermen no longer use "pole bombs" to keep raptor birds from robbing their fish traps.
On our farms, modern combines leave lots more grain and oilseeds on the ground for birds than when farmers removed the whole plant (grain and straw) to a threshing floor far from the field.
According to the breeding bird survey by the U.S. Fish and Wildlife Service, most of the over 250 bird species tracked increased in population between 1966 and 1991, the heyday of pesticide use expansion in America.
Finally, of course, high-yield farming and pesticides have been raising more food on less land, leaving more land in wild habitat.
The United States has expanded its forest land and wildlands by millions of acres in recent years, even as it exported more food to densely populated Asian countries.
Worldwide, farming's Green Revolution has preserved at least 15 million square miles of wildlands from the plow. (The world's total forest area is 16 million square miles.) That means homes for billions more forest birds.
The level of pesticide safety indicated by the New York bird autopsies seems to indicate modern farming is also pretty safe for birds.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.