Birds 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 $47,000. 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.