Ethical pigeon control using nicarbazin

Barcelona City Council’s Wild Fauna Ecopathology Service (SEFaS), aims to respond to the problem of pigeon management in Barcelona's urban area by supplying maize grain laced with nicarbazin to control pigeon breeding there.

The initiative comes in response to concerns and demands from the public to control the overpopulating while respecting nature and biodiversity, by implementing a benchmark project in the urban management of wild fauna species.

Specific aims of pigeon control

  • Reducing the overpopulation of Barcelona's urban pigeons to numbers acceptable to society.
  • Lowering the number of problems and incidents caused by pigeons in Barcelona city.
  • Establishing a long-term management method, by setting management strategies that enable an acceptable number to be maintained over time.

The project

The pigeon sterilisation project in Barcelona will be carried out simultaneously and in coordination in the city's 10 districts.

The criteria for selecting and prioritising the treatment distribution points were as follows: numbers and density of pigeons at the points, degree of conflict in the area determined by the number of incidents recorded, the damage caused to the area and the proximity to places at greater risk such as markets, schools, retirement homes and healthcare centres.

Treatment

The project involves distributing maize grain laced with nicarbazin, a substance that inhibits the reproductive capacity of pigeons as it prevents the formation of egg yolk, causing reversible infertility.

An automated dispensing device allows programmed distributions of the product at all the administrative points simultaneously at a specific time. This enables greater distribution of the treatment within the population by preventing the same pigeons from moving and feeding among several administration points.

The annual duration of the treatment with Nicarbazin is 8 months, from 15 March to 15 November. It is distributed 5 days a week, from Mondays to Fridays. The treatment supply time starts at 8 am from March to June and at 7 am from July to November.

The time usually corresponds to when the concentration of pigeons is at its highest and the probability of a pigeon having obtained enough food to satisfy its daily requirements is at its lowest, thereby ensuring pigeons ingest their daily dose of nicarbazin. The difference in supply times depending on the month is due to the daylight savings change in time.

Controlling the treatment’s effectiveness

The project will see two types of registers being compiled for pigeon numbers in Barcelona: a comprehensive census and abundance estimates (maximum number of pigeons in a group) at administration points.

These registers will help to ensure good monitoring and control of the project's development. They will contribute information not just for analysing the effectiveness of the treatment but also for controlling and making decisions over possible changes.

Estimates will be made of the numbers of the groups of pigeons at the points chosen for administering the treatment and control. The results of these estimates will be used for determining the maximum number of pigeons at each point as well as the development of numbers of groups during the treatment. These results will also help to ensure the availability of food for the entire group of pigeons as the doses of nicarbazin that are distributed every day can be changed according to the number of the pigeons in the group.

Data for the population estimates will be collected by a repeated measure count (three days per period and point) in three different periods of the year: before, during and after treatment.

Studying and monitoring the administration points

Each administration point will be visited frequently to ensure the treatment distribution device functions properly and that the attraction factors in each area (direct or indirect feeding, rearing places, etc.) as well as their development are studied.

Periodic checks will be made during these visits on the number of pigeons treated at each administration point to gather information on the variations that may be arise, to adjust the doses that are distributed and to optimise the product's distribution.

Analyses will also be made to prevent other species of animals from eating nicarbazin. It will be of great interest for the project, being one of its control goals, to find out whether other species eat it.

The analyses of incidents are an indirect but very important source of information for finding out about an area's situation. Incidents reflect public perceptions of the problem and are usually a reliable indicator of numbers. The development of incidents during the project is likewise an indicator of the effectiveness of the control method.

Expected results

Experiences gained in other cities such as Genoa (Italy) show that, on average, the first year of treatments leads to a reduction of around 20%-30% (though there can be fluctuations according to area) and after 4-5 years the reduction rises to 80% of the original population.

The Wild Fauna Ecopathology Service (SEFaS)

The Wild Fauna Ecopathology Service (SEFaS) at the Autonomous University of Barcelona (UAB)'s Faculty of Veterinary Medicine acts as a study and communication nexus for the project, through business, science community, public and administrative collaboration.

The aim is to improve knowledge about the biology and presence of pigeons in Barcelona, as well as to reduce their population numbers and incidents that occur.

The SEFaS’s work in this project involves planning, supervising and evaluating the effectiveness that sterilisation with nicarbazin has in controlling urban pigeons in Barcelona.

The project's implementation, evaluation and follow-up has to reduce the population of pigeons in urban spaces, thereby resulting in a lower need for one-off initiatives in conflictive areas and better health and conditions for Barcelona's urban pigeons.