Avitrol is used to poison pigeons and other birds—blackbirds, crows, sparrows, house sparrows, and pigeons. Its active ingredient, 4-aminopyridine, acts on the central and motor nervous system. The poison causes birds to react in a way that makes them look like they are convulsing or having a seizure. Birds that eat the bait that has been treated with Avitrol will display distress and cause other birds to leave the area. If the dosage amount is deadly, the bird will typically die in less than an hour. If the dosage is not quite lethal, the bird may recover in four or five hours and will show no lasting signs of the poison.
The Human Society is against Avitrol poisoning. One observer who witnessed birds who had received the poison said the birds were flying around acting drunk before they fell to their deaths.
The Humane Society reported that Avitrol, which is sold as a repellent, is a toxicant to the nervous system and harmful to animals. They also said it causes those who ingest it to have convulsions, fly irregularly, make loud noises, and die. The society reported that 151 to 175 pounds of 4-aminopyridine were sold in the United States every year between 2002 and 2006. This, the society states, would kill more than a couple hundred million birds a year.
A multitude of dead birds brought about fears of a terrorist attack back in 2007 in Washington, D.C. This caused metro stations to shut down. After the U.S. Environmental Protection Agency examined what caused the deaths, they reported it was 4-aminopyridine. Products with this ingredient are often used by pest control professionals who are licensed.