R-12 is harmless for humans, animals and the environment. The active ingredient is used in poultry farming for the prevention of coccidiosis. It is administered until the last day of life, which means it satisfies all rules relating to food safety and animal welfare. R-12 only contains a minimal dose of the active ingredient, and is therefore safe for all parties involved.


  • A person would have to eat 750 kg per day for there to be any health risk.


  • R-12 does not cause any long-term consequences or lasting injuries to pigeons.

  • It also protects them against coccidiosis, a fatal disease.

Birds of prey

  • A bird of prey that eats a pigeon that’s been treated with R-12 does not become infertile. Nicarbazin, the active ingredient in R-12, is broken down into two components in the liver. This means the substance is no longer active by the time the bird of prey ingests the pigeon.

  • Nor is the nest of the local pair of peregrine falcons at risk. This is evidenced by these images from Agfa-Gevaert's chimney, one of the locations where Vets For City Pigeons operates. For the local pair of peregrine falcons also had a healthy nest of four young.

  • In Leuven, Vets For City Pigeons has been feeding pigeons with the pigeon pill for years. In May 2022, a pair of eagle owls was spotted with three youngsters in the centre of Leuven, another proof that the pigeon pill is safe for birds of prey.

Other birds

  • Other birds and pigeons that might want to eat the food are rarely given the chance by the dominant urban pigeons. Other birds – including the Eurasian collared dove – are often smaller and cannot ingest the corn kernels.

  • Corn kernels were deliberately chosen as the method of administration to prevent other birds from also being able pick up grains. They are large, consistent and do not change shape.

The environment

  • This contraceptive does not contain any hormones, so no harmful substances are deposited in the soil or surface water.

  • The amount of nicarbazin that could be released into the environment during treatment is at least 100 times lower than the EEC directive for environmental risk assessment.

A single R-12 corn kernel contains approximately 0.00032 grams of nicarbazin.

A pigeon consumes only 8-10 grams of R-12 per day. This equates to 0.008 grams of nicarbazin.

The administration of R-12 is selective and local. Mainly the dominant pigeons are targeted. It is administered to them at least five times per week – during the mating period.

The sterilisation is fully reversible. When R-12 is no longer being administered, fertility is restored after 4-6 days.