It’s been proven to work — at least, with cherry tomatoes.
Railings, benches, statues, cars, sidewalks and, in the worst case scenario, in our hair. Pigeon droppings are everywhere in urban areas.
Many people don’t like them — they even call them “rats with wings” in a derogatory tone. Others feed flocks and make them stay.
According to experts, the problem is not the existence of pigeons themselves, but their excessive concentration: these birds should not be “criminalized”, highlights Xabier Cabodevilla, researcher at the University of the Basque Country, to .
Although the health danger is not considered extreme, there are risks. Pigeon feces may contain bacteria causing gastrointestinal problems, such as Campylobacter, Listeria, Salmonella or Yersinia, as well as fungi and parasites. Children, immunosuppressed people or those who have direct contact with excrement in parks and streets are particularly vulnerable groups.
There is also a material problem. Unlike mammals, birds do not eliminate urine and feces separately. Everything comes out through the cloaca, in a mixture that contains urea and acidic compounds, visible in the white part of the bowel movements. This acidity makes highly corrosive excrementcapable of damaging car paintwork and degrading stone, metal and elements of historical heritage.
From coconut to something useful
Faced with so much organic matter lost on the streets, it would be tempting to imagine a useful use: transforming excrement into fertilizer.
After all, bird feces have been used in agriculture for centuries. The best-known example is the guanoaccumulated by seabirds on islands and coastal areas, rich in nitrogen, phosphorus and potassium. Its importance became strategic to the point of being linked to the War of the Pacific, in the 19th century, involving Chile, Bolivia and Peru.
But pigeon excrement is another story. In theory, its composition could make it useful as fertilizer. But in practice, there are obstacles that are difficult to overcome.
The big problem is in collection. On the streets, feces mix with dust, stones, dirt, urban waste and contaminants. This material stops being just organic matter and becomes part of a “cocktail” that is difficult to control.
For composting to be viable, it would be necessary to concentrate large amounts of waste in a controlled location — precisely the type of pigeon concentrations that cities must avoid. The situation is different in pigeon lofts or poultry farmswhere the excrement of birds, such as chickens, is centralized and “pure”.
Home use is also not recommended. Directly applying pigeon feces to pots or gardens can pose a risk to both plants and people, experts warn.
Even so, the idea has already been tested in France. In 2012, in Paris, designer Jean-Sébastien Poncet proposed the creation of urban terracotta pigeon lofts to collect excrement and transform it into fertilizer, in an artistic project called .
Years later, French researchers proved in a scientific test that this poop may have fertilizer potential. In a 2023 study, tomate cherry grown on a terrace in Ivry-sur-Seine, near Paris, they grew faster and flowered more when they received pigeon droppings diluted with water. The difference was in the treatment: the guano was sterilized at 121 degrees Celsius and under pressure for 20 minutes, to eliminate potential pathogens.
