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Birds are at Risk from Garden Pesticides

An Incident

In the early 90s, following a routine application of the insecticide diazinon to the turf of a condominium, 47 mallard ducks were fatally poisoned. The Oak Park, Illinois lawn-care company responsible, although apparently observing the written product label directions, was nevertheless fined $4,700. The professional applicator was found guilty of a misdemeanor under the Migratory Bird Treaty Act.*

The Problem

Birds are at risk from exposure to pesticides

Many people feed and provide water for birds in their backyards. Many of these bird-lovers also use chemical pesticides on their lawns and gardens. No doubt they are unaware of the potential dangers to their feathered guests resulting from contamination, particularly by the chemical pesticides that are cholinesterase inhibitors,** such as diazinon and chlorpyrifos. Those who are concerned with avian health need to know how lawn and garden pest control chemicals can harm birds, and the legal implications of pesticide-related bird deaths.

Thousands of bird fatalities linked to cholinesterase inhibiting pesticides are in the files of the US Fish and Wildlife Service, the US EPA, state agencies, and research organizations.

Products containing cholinesterase inhibitors as active ingredients are available under various trade names. They are among the 44 pesticides most commonly used in lawns and gardens but identifying them can be difficult from the label alone.

Inhibition of the cholinesterase enzyme is an effect which results in excessive stimulation of the victim's nervous system. The result may be death or non-fatal neurotoxicity. Poisoned birds which do not die can have reduced body temperature, changes in the ability to capture prey or avoid predation, changes in reproductive or parenting behavior, and changes in the ability to navigate during migration. Alterations in birds' ability to respond to their environment can lead to decreased survival of individuals or even of the species.

Organophosphate and carbamate pesticides not specifically linked to bird fatalities are hazardous because they reinforce the toxicity of other cholinesterase inhibitors through their common mode of action.

Scientists report that populations of migratory birds are actually decreasing. Experts disagree on the reasons for the decline, but some have implicated pesticides.

According to Ward Stone, wildlife pathologist:

"Problems arise [in backyards] when high avian toxicity cholinesterase inhibitor insecticides such as diazinon, chlorpyrifos, isofenphos, bendiocarb, and ethoprop are applied to grassy areas under and near bird feeders. The birdseed that has been spilled from the feeder can readily be poisoned. Water in bird baths can be contaminated by pesticide drift from chemicals sprayed on gardens and lawns."

A Solution

"Unnecessary bird mortality can be avoided by not using pesticides on turfgrass where birds are fed, or by taking great care not to apply pesticides close to feeders or birdbaths." (Ward Stone)


Bird fatalities associated with pesticide use often are not adequately documented.

Incidents of non-fatal bird poisonings are virtually undocumented at this time.

Are individuals responsible for "taking" or killing migratory birds with pesticides guilty of breaking the law?

Some would say yes.

The Migratory Bird Treaty Act makes it illegal to "take" or kill a migratory bird. Under the Act migratory birds are most of those we enjoy seeing at our backyard feeders: goldfinches, cardinals, mourning doves, hummingbirds, woodpeckers, robins, chickadees, etc.

The label for the product used in Oak Park did not then, and does not now, inform the user that killing migratory birds through the use of chemical pesticides violates the Migratory Bird Treaty Act. The product label does state that birds can be killed at the recommended level of use.

Labeling for the diazinon-containing pesticide involved in the Oak Park incident now states that the product represents a hazard to birds. Does this imply that other products without specific warnings concerning birds on their labels (but containing EPA-registered chemicals) are harmless? No, it does not!

The use of any chemical pesticide involves risk. This is reflected in the EPA Policy that does not allow pesticide manufacturers to label their products as being safe.

* Migratory Bird Treaty Act, s 2 et seq., 16 U.S.C.A. s 703 et seq. (West 1985 & Supp. 1995).

** For more information on cholinesterase inhibitors see organophosphate and carbamate chemical class information and also the charts for diazinon, chlorpyrifos, isofenphos, bendiocarb, and ethoprop in the Basic Guide to Pesticides or see the sample entries from the Basic Guide and Glossary.

A Pledge of Protection from Pesticides: Birds, Bees, Bivalves

People say that pesticides are toxic to wildlife. But where is the evidence? A commonly overlooked source is the labeling for certain EPA-registered pesticides that include warnings of the dangers that chemical pesticides pose for wildlife. A few contain even stronger statements prohibiting use of the pesticide around wildlife.

Many Americans cannot or do not read or understand pesticide product labels (1994 study by Lockwood, et al) Citizens concerned about effects of pesticides on wildlife need to be aware of and call attention to warnings and precautions on pesticide labeling.

The widely sold organophosphate insecticide, diazinon, can be expected to kill numbers of wildlife according to warnings and prohibitions on its EPA-approved labeling. Scientific presentations from our Wildlife, Pesticides and People Conference reported the wide-spread distribution of diazinon in urban surface water indicating frequent use by homeowners.

An application of diazinon that might kill birds can contaminate tributary streams or even reach the Bay and poison the fish, the crabs, the oysters. It can also drift overland and poison the bees and other beneficial insects. The breakdown products of diazinon are even more toxic than the parent chemical. Diazinon's breakdown products are TEPP and sulfoTEPP. TEPP has been taken off the market due to toxicity. Recent reports from USGS have shown that breakdown products levels can be 50 to 100 times greater than those of the parent compounds in pesticide-contaminated streams.

Wildlife can be at risk when products with toxic active ingredients such as diazinon are widely available to home owners who may not read, comprehend or pay attention to pesticide product labeling.

The U.S. Fish and Wildlife Service has enforced an international agreement, the Migratory Bird Treaty Act (MBTA) to protect neo-tropical migrants from pesticides. (see Birds at Risk from Garden Pesticides above, for details.) A pesticide user would be breaking the MBTA if even one migratory bird death is caused by his or her pesticide application. And the law can still be enforced even if the pesticide user is unaware of it.

The diazinon label prohibits (this is stronger than a warning) use around "bees" and "aquatic resources."

Greater consumer awareness of these statements could help protect wildlife from pesticide poisoning.

Specific diazinon label instructions include the following statements:

Warning: "Birds, especially waterfowl, feeding or drinking on treated areas may be killed."

Prohibition: "Do not apply this product or allow to drift to blooming crops or weeds if bees are visiting the treatment area."

Prohibition: "Do not apply where fish, shrimp, crab or other aquatic life are important resources."

How closely should one follow directions on a pesticide label?

Each EPA registered product bears on its label the admonition: "It is a violation of federal law to use this product in a manner inconsistent with its labeling." In other words, it is illegal to use the product in any way except as instructed on the label.

How well do users follow directions?

Since the wording of precautions and warnings may appear ambiguous and in conflict with the directions for use, many users tend to disregard them.

What would concerned citizens do?

People whose primary concern is for the environment would give higher priority to the protection of wildlife, could closely follow the warnings and precautions and would point them out to others. You can use the EPA-registered product labeling to help protect wildlife and ultimately ourselves when you:

Birds at Risk from Insect Sticky Traps Used Outdoors

Strips with a sticky adhesive are becoming more common as a means of trapping insects. When placed outdoors they can also attract and trap small insect-eating songbirds such as the Carolina wren, titmouse, and nuthatch. Removal of small birds trapped on the sticky surface is fraught with its own problems. Even if the removal is successful the birds may spend extensive time at the rehabilitation facility to replace lost feathers. Alternatively severe injuries such as dislocations may require euthanasia. Bird rehabilitators have become dismayed by birds stuck to the traps and have contacted Rachel Carson Council for help with informing the public of this distressing situation. Snakes may also adhere to such traps and lose part of their skin in breaking free of the sticky surface.

We are recommending that insect traps with adhesive surfaces not be routinely used for outdoor pest control by homeowners. Please call the Council if you have or need further information on this subject.