Introduction: 4-Aminopyridine, a pyridine compound, is an extremely effective bird poison. It is one of the most prominent avicides. It is registered with the EPA for use against red-winged blackbirds, blackbirds in agricultural fields, grackles, pigeons, and sparrows around public buildings, and various birds around livestock feeding pens.
Avitrol repels birds by poisoning a few members of a flock, causing them to become hyperactive. Their distress calls signal other birds to leave the site. Only a small number of birds need to be affected to cause alarm in the rest of the flock. After one alarming exposure, birds will usually not return to treated areas. Avitrol is available as grain baits or as a powder concentrate.
Toxicological Effects:
* Acute toxicity: 4-Aminopyridine is highly toxic to mammals. The central nervous system is strongly excited by 4-aminopyridine. Based on observations with 2-aminopyridine, a similar compound, individuals with a history of convulsive disorders may be at an increased risk from exposure to 4-aminopyridine [30,31]. The principal action of 4-aminopyridine in the body is to encourage message-carrying (transmitter) substances to be released throughout the nervous system, overstimulating it [68]. While intended strictly for use as a bird repellent, accidental ingestion of as little as 60 mg has caused severe poisoning in adult humans [68]. It is rapidly absorbed from the gastrointestinal tract [8]. Poisonings are characterized by thirst, nausea, dizziness, weakness, and intense sweating, followed by impairment of normal mental functioning (toxic psychosis), lack of muscular coordination, tremors, labored breathing, and generalized seizures [167].
Symptoms of Avitrol poisoning in rats, dogs, and horses include over-production of saliva, tendency to become over-stimulated, and trembling, which can progress to convulsions. Death can result from respiratory arrest or heart failure [23,30]. Skin exposure to Avitrol may lead to systemic intoxication or general overall poisoning [30]. Avitrol may contribute to the excessive formation of a substance called methemoglobin. Methemoglobin is similar to hemoglobin, the oxygen-carrying part of the blood, except that it cannot carry oxygen. When there is excess methemoglobin in the blood, oxygen cannot be transported and blood eventually becomes oxygen depleted, resulting in the condition methemoglobinemia.
The LD50 for 4-aminopyridine is 20 to 29 mg/kg in rats, and is 3.7 mg/kg in dogs [8,167]. It is readily absorbed through the skin [23]. The dermal LD50 is 326 mg/kg in rabbits [23,30]. 4-Aminopyridine is an eye irritant. Inflammation of the iris and conjunctivitis were noted in the eyes of albino rabbits 1 hour after 10 mg of 4-aminopyridine hydrochloride were applied. These symptoms disappeared after 7 days [167].
* Chronic toxicity: High dietary doses (2 to 3.25 mg/kg/day) caused increased brain weight. Brain appearance remained normal [167]. However, since dietary intake is assumed to be negligible, and because significant repeated exposure is not expected to occur, EPA has not required long-term toxicity studies of 4-aminopyridine [167].
I think they would have been using DRC-1339 for the pesticide, since it has lower secondary kills.
Avitrol is nasty stuff. It is best used for grackles - when grackels become erratic, the rest of them clear off. We used to have grackles on our farm by the hundreds. Hated them with a passion. I could get them to clear off for a day by blowing one up with the .17HMR in a very public manner. The .17 is wonderful for this — the target bird just explodes into a puff of feathers. You hear all this squawking and carrying on in the trees and in the shops, and they just clear off for the day.
Never used Avitrol. I figured the paperwork was too much hassle.