This European city put pigeons on contraception

Man feeding pigeons in Plaça de Catalunya, Barcelona. Photo: David Ramos / Getty Images

Urban pigeons have long become a challenge for many European metropolises. Their droppings spoil facades and monuments, the birds settle near markets and cafes, and flocks in tourist areas cause complaints from residents and businesses. In Barcelona, as in other large cities, the problem has particularly worsened in the city center and densely populated neighborhoods.

For a long time, authorities tried to control the number of pigeons using traditional methods — nets, traps, culling, and other methods of physical extermination. But such measures drew increasing criticism from animal welfare advocates, and their effect often proved temporary: the population quickly recovered.

The search for humane alternatives began in the city back in 2017 when Barcelona launched a pilot project using avian contraceptives. This approach gained final recognition after Spain adopted a new animal protection law in 2023. The document banned indiscriminate culling and killing of urban birds, obliging local authorities to prioritize ethical and non-lethal methods.

Thus, Barcelona's experience in birth control became the main strategy: instead of eliminating birds, the focus is now on naturally and gradually reducing their numbers.

"Smart" Feeders

Today, Barcelona has over 40 special dispensers, similar to waste containers. Every morning, exactly at eight o'clock, a built-in timer releases a certain amount of corn.

But this is no ordinary feed: each grain is treated with nicarbazin — a drug that acts as a contraceptive for birds. Just 10 grams of such corn per day is enough for pigeons to start laying eggs from which no chicks will hatch.

Moreover, the effect is not considered irreversible: if the bird stops receiving the drug, fertility gradually returns.

Nicarbazin itself was not developed specifically for urban birds. It has been used for about 70 years in poultry farming to prevent coccidiosis — a parasitic disease in chickens. The drug is still used today, including in some broiler production. It was during many years of use that it was noticed that the substance affects bird reproduction. No contraceptive effect has been found in other non-avian animals.

The corn for Barcelona's program is produced in Italy. Nicarbazin is injected into each grain, after which it is covered with silicone to prevent the substance from washing out. The drug is sold under the trade name Ovistop.

In Barcelona, the dispensers do not stay in one place permanently. They are moved to where the number of birds begins to cause the most complaints. For example, a dispenser located in La Pegaso Park dispenses about 500 grams of corn daily — enough for approximately fifty pigeons.

Supporters of the program emphasize that the goal is not the complete eradication of pigeons. According to estimates, about 90,000 of these birds live in Barcelona, and contraceptive feeders affect only a small part of the population. But authorities hope this is enough to reduce the density of birds in the most problematic areas.

Is there a result?

Studies yield mixed results. In one, which lasted three years and covered 34 pigeon colonies, a reduction in the number of birds by more than 55% was recorded thanks to the use of nicarbazin dispensers.

Another scientific paper showed that over eight years in 24 cities in Catalonia, the contraceptive method "significantly reduced local pigeon numbers with minimal impact on other species."

But there are also studies with opposing conclusions. An article in the journal Pest Management Science in 2020 claimed that the use of nicarbazin did not lead to a noticeable reduction in pigeon numbers in large cities. The authors even advised against using this method in metropolises.

Proponents of the system respond that the problem lies in the scale and duration of observations. In their opinion, one year is too short a period to assess the results, as pigeons reproduce throughout the year, and their numbers in the city constantly fluctuate due to migration between areas.

Challenges in adopting the experience

However, as The Telegraph notes, even if the effectiveness of the method is proven, it is not easy for other countries to adopt Barcelona's experience. The main obstacle is the complex legal status of the drug.

In the European Union, nicarbazin is registered primarily as a feed additive for poultry. To use it for urban pigeons, each country has to go through separate approval procedures.

Павялічыць

Rambla del Raval Boulevard in Barcelona, April 29, 2026. Photo: David Zorrakino / Europa Press via Getty Images

In Italy and Belgium, the drug is permitted through national registration mechanisms, and in some regions of Spain — through a special "therapeutic exemption" rule, which applies when there is no other official solution to the problem.

Similar bureaucratic difficulties hinder the implementation of the method in the UK: they have not yet decided how to classify such agents — as veterinary medicines or as pest control agents.

Despite these legal and scientific disputes, interest in "pigeon pills" is only growing worldwide. The fact is that Barcelona's experience is not an isolated experiment, but part of a large-scale global trend called "wildlife fertility control."

Today, scientists are developing similar programs for a wide variety of species: from grey squirrels in Britain to capybaras in Brazil and even elephants in Africa. Nicarbazin-based drugs are already officially used in the USA, Canada, Australia, and the UAE.

Such popularity is explained by a shift in public priorities, where ethics and safety come first. In the modern world, people are increasingly reluctant to accept the killing of animals as a way to solve problems, even when it comes to pests.

Furthermore, remote contraception is considered safer for the environment: unlike poison, it does not enter the food chain and poses no threat to domestic dogs or wild birds of prey.

Barcelona's example shows that the future of urban ecology can be based not on destruction, but on technological and humane coexistence.

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