three birds sitting on a ledge with New York City in the background

This bird pesticide is legal, but recent deaths are stoking controversy

“Both physically and psychologically, it’s an awful way to die,” says one conservationist of the bird poison Avitrol. Cities around the U.S. and Canada agree—and some have banned it.

Avitrol, an EPA-registered bird pesticide, often causes birds to fall to the ground, convulse, and die—a reaction that horrifies onlookers. The product is banned in many places, including in New York City.

Photograph by George McKenzie Jr.

“It’s OK,” Bonnie Siegfried said softy, trying to comfort a convulsing pigeon wrapped in a fleece blanket. The bird’s body was twitching violently, its beak chattering as she held it in her arms. The pigeon died after about a half an hour as Siegfried, who lives in London, in the Canadian province of Ontario, waited for an animal control officer to arrive. She later posted a video of the pigeon to Facebook.

In the weeks after that incident in late August 2020, several London, Ontario residents and neighbors reported seeing numerous pigeons in distress—falling out of trees, flapping their wings, convulsing, gasping in distress, and dying. A necropsy later concluded the pigeons had been poisoned with Avitrol, a chemical poison used against birds. Avitrol has been approved for use in the United States by the Environmental Protection Agency since 1972 and was re-registered in for use in Canada in 2016—though it has been banned in London and other parts of Canada, and in several U.S. cities. The EPA lists Avitrol as an avicide, a word defined as “the killing of birds.”

Mainly used in the U.S. and Canada, according to the National Audubon Society, Avitrol is the only commercially available EPA-sanctioned avicide. (Another avicide, DRC-1339, is EPA-approved but can be used only by the U.S. Department of Agriculture.) Avitrol is toxic to all vertebrates that ingest it and is classified in the U.S. as a restricted use pesticide, so only licensed pest control professionals can apply it.

Avitrol Corporation describes the product as “humane bird control” and says its product is not intended to kill birds, although it acknowledges some die after ingesting it. Instead, it describes Avitrol as a “chemical frightening agent” that painlessly acts on birds’ central and motor nervous systems, causing them to display “behaviors similar to an epileptic seizure”— “flying erratically, vocalizing, trembling, dilation of the pupils, and other symptoms.” This reaction is intended to frighten other birds away.

Animal welfare advocates, however, point to videos like Siegfried’s and research by the Humane Society of the United States into the product’s active ingredient, 4-aminopyridine, to argue that Avitrol causes pain and unnecessary distress. Furthermore, multiple incidents of mass bird deaths, such as in London, suggest the product is often used to exterminate rather than repel birds. Advocates also worry that the poison could accidentally kill wildlife that prey on pigeons, such as the endangered peregrine falcons in Canada that local governments have sought to protect by restricting the chemical's use.

Avitrol Corporation’s website says it has “never had reports” of secondary poisonings in 50 years of operating. But a 2013 study published in the Journal of Toxicology reviewed 29 Avitrol poisonings of non-target species—25 dogs, three cats, and one bovine. One dog died, and five were treated and recovered; outcomes for the other animals are not known.

Avitrol Corporation did not respond to numerous requests for an interview.

People and businesses have various reasons for wanting to get rid of birds—most commonly pigeons, but also house sparrows, blackbirds, grackles, and crows. Because of their feces, they’re often considered a nuisance. They can also spread disease, including the bird-borne infection histoplasmosis, which can cause fever, chills, headaches, and other symptoms. Farmers may also want them gone to stop them from eating their livestock’s food supply. Nonetheless, many countries have moved away from using poison to manage “pest” birds, the Audubon Society says, and avicides are banned across much of Europe and the United Kingdom.

No organization tracks the use of avicides globally, so it’s unclear how many countries permit their use and how widespread they are.

The EPA tracks pesticide usage in the U.S., but it doesn’t necessarily track precise quantities. According to an EPA spokesperson, national usage data for Avitrol is not collected.

‘An awful way to die’

An avicide such as Avitrol is “extremely inhumane,” says Stephanie Boyles Griffin, senior scientist of the wildlife protection department at the Humane Society of the United States, based in Washington, D.C. As a neurotoxin, a poison that attacks the nervous system, she says, Avitrol can overstimulate the senses and trigger seizures. “Anybody that’s ever had a grand mal seizure…knows how traumatic it is.”

People who witness birds dying in streets have reported the occurrences to their wildlife authority. Post-mortems have often revealed Avitrol as the cause, and some local governments—including New York City; San Francisco; Boulder, Colorado; and Portland, Oregon—have banned the use of Avitrol and other avicides.

Residents of Portland were shaken after two incidents, in 2014 and 2018, when crows were “literally raining down from the sky,” crashing onto the pavement, screaming and flapping, their eyes rolling back in their heads, says Bob Sallinger, director of conservation at the Audubon Society of Portland. “They would lie on their sides and pedal their feet and seizure and then die,” he says. Their carcasses littered 30 to 40 city blocks. “Physically and psychologically, it’s an awful way to die.” (Crows are known for their high intelligence.)

Sallinger and colleagues at Audubon of Portland collected dozens of the birds for analysis, and the cause was determined to be Avitrol, though the distributor was never identified. “The question for our community was whether this product was acceptable within Portland,” he says.

At a city council meeting on June 5, 2019, the Portland community responded with a “resounding no,” Sallinger says. The council voted to ban the use of Avitrol on city-owned land. Even members of the local business community—many of whom have an incentive to get rid of nuisance birds—spoke out against the poison.

“It’s rare that action is actually taken on pesticides at the local level, but this one has generated opposition in a variety of places where communities have felt compelled to step in and do what the EPA has not been willing to do,” Sallinger says. “I think it really speaks to what a bad product this is and how irresponsible it is to use it.”

Rarely used as intended

Avitrol’s labeling details the EPA’s requirements for its correct use: limited, scattered distribution in areas that provide feeding opportunities for only the necessary number of targeted birds.

Experts say Avitrol is rarely used as intended, however, and Sallinger says it’s difficult, if not impossible, to limit how much of the poison birds ingest.

The EPA says that only licensed professionals who have undergone training from their state’s pesticide regulatory agency can distribute Avitrol and that every state’s certification program is federally approved by the agencyIn 2013, the EPA beefed up Avitrol’s labeling to include where the bait could be applied, monitoring of the bait after it’s applied, and disposing of dead birds.

A pesticide’s “label is the law,” the EPA says. If a registered pesticide is being used “in a manner inconsistent with its labeling,” the EPA can stop the sale of the product.

Even though the effects of the avicide are “visually repugnant,” as noted in a study published on Avitrol’s website, the company states that careful distribution of it to frighten flocks can result in “little or no mortality.” The EPA concurs: “Given the low expected bird mortality via use of Avitrol compared to alternatives (e.g., shooting),” the product is “humane.”

But, Sallinger says, Portland provides an example of how Avitrol’s labeling isn’t always followed. The EPA’s label requires users to collect and bury or incinerate carcasses, but that didn’t happen with the dead crows in Portland. Sallinger says he spent days after the die-offs picking up carcasses and putting them in trash bags. “I think EPA is remiss in licensing this [product] because there’s no way to ensure that you can meet the requirements of the label.”

‘An outrageous claim’

Regardless of whether Avitrol is used correctly, the company’s assertion that it’s humane is “an outrageous claim,” says Travis Longcore, science director of the Urban Wildlands Group, a Los Angeles-based conservation nonprofit. “You’re causing birds to undergo at least extreme discomfort, more than likely pain, and occasionally death, to ‘scare’ the rest of them away,” he says. “It’s common sense inhumane.”

In 2007, the Humane Society of the United States commissioned Longcore to write a report on 4-aminopyridine, the active ingredient in Avitrol. Contrary to Avitrol’s claim that the birds are in a “depressed state” and “cannot feel pain” before the onset of convulsions, Longcore found that exposure to 4-aminopyridine actually “enhances sensation from the nerves,” causing a tingling sensation and abdominal pain.

Avitrol increases levels of acetylcholine, a neurotransmitter that controls muscle contractions. Humans suffering from multiple sclerosis may be prescribed drugs containing 4-aminopyridine; those who accidentally overdose “report burning in the throat and abdominal discomfort followed by nausea, irritability, weakness, dizziness, ‘feelings of impending doom,’ thirst, and shortness of breath,” according to Longcore’s report. High enough concentrations can also cause convulsions, as seen in birds poisoned with Avitrol.

In a study published on its website, Avitrol claims that during convulsions, “the animal cannot feel pain because it cannot remember the experience.” The study claims this “observation at least is true for human beings.” But Longcore noted a dearth of evidence that birds are not aware during seizures, and it’s known now that humans can be aware during focal seizures that begin in one area of the brain.

Ultimately, regarding the question of pain, “we can’t ask the birds,” Longcore says. But “there’s sort of no question that they feel pain, whether it’s during the seizure or after the seizure when they’ve beaten themselves up on the ground.”

Humane alternatives

The Humane Society’s Stephanie Boyles Griffin says people turn to Avitrol because they think it’s a “quick fix.” But “of course, that’s not true,” she adds. Birds that see others in distress may be frightened off for a time, but they always come back.

Boyles Griffin, who describes herself as a “big pigeon fan,” is convinced that most people don’t want to harm wildlife. “People are generally tolerant of our wild neighbors, pigeons being one of them, and when they solve a problem with them, they prefer the non-lethal, humane approach.”

The good news, Boyles Griffin says, is that there are many alternatives that “work better than the cruel, lethal approaches.” Some involve changing human behavior—for example, the simple fix of not feeding birds so they don’t congregate. Nets and spikes can also prevent or deter birds from landing on trees and buildings near heavily trafficked sidewalks or statues, where their droppings are often considered a nuisance.

Another option is “planned pigeonhood,” says Erick Wolf, CEO of OvoControl, the only company that makes a birth control kibble. His product blocks the sperm receptors on the female pigeons’ eggs. If the kibble is available in an automatic feeder, the birds will return every day to eat it. Within three months, the flock and their droppings will start to diminish, Wolf says.

Another sidewalk-cleaning approach, used by Portland in the midst of the crow die-offs, is a ride-on sidewalk scrubber, jokingly called “the Poopmaster 6000.” The city also has hired falconers to release Harris’s hawks to scare crows off to another roosting site. It’s all part of humanity’s “responsibility to coexist” with wildlife, Portland Audubon’s Sallinger says.

Given the range of alternatives and the growing opposition to Avitrol, he says it’s time for the EPA to stop registering the poison. “There are an increasing number of municipalities that have said, ‘Not in our community.’ I think that is very significant, and I think the EPA eventually will have to pay attention to that.”

According to the EPA, Avitrol is undergoing routine registration review, which occurs every 15 years. Possibly by the end of this month, the agency says it will complete a draft risk assessment of the avicide, in which the EPA characterizes the nature and scale of health risks to humans and the environment. Such product risk assessments are done routinely and made available for the public to review and comment on. “EPA will carefully assess all feedback provided during the open comment period.” Eventually, the EPA will reach a final decision over whether to re-register the product.

This story was updated on April 22, 2021, to clarify that the EPA does not collect national usage data for Avitrol.

Wildlife Watch is an investigative reporting project between National Geographic Society and National Geographic Partners focusing on wildlife crime and exploitation. Read more Wildlife Watch stories here, and learn more about National Geographic Society’s nonprofit mission at Send tips, feedback, and story ideas to

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