Sometimes the most altruistic or generous acts can become counterproductive. One of those cases is to feed the pigeons. It might seem like entertainment without consequences, or that after all, we enjoy a good number of hungry animals.
But neither one thing nor the other. Feeding pigeons is negative for both pigeons and cities, as suggested by a study of researchers from the Museum of Natural Sciences of Barcelona and the Public Health Agency of Barcelona.
The study, published in Pest Management Science, that the progressive increase of pigeons in urban environments throughout the twentieth century has caused serious problems, such as the deterioration of urban architecture and the transmission of infectious diseases.
In Barcelona, for example, there is a density of 4,242 pigeons per square kilometer. But in areas where access to food was limited to pigeons, they reduced their numbers, which this strategy proves to be effective in controlling their overpopulation.
But the study also found another effect: applying this reduction to the availability of food, the average size of the pigeon heads, as well as the lengths of the wings, increased, while the body mass decreased, which was good for them.
According Juan Carlos Senar, principal investigator of the study:
More than 15 years of study have led to the conclusion that the best way to control any species of bird is to influence the key factors, called limitations, and this produces better and more lasting results in the long term.
As for the investment that requires such an action, according to Senar:
It is estimated that each pigeon produces between 5 and 10 kilos of corrosive droppings each year. Based on this, it has been estimated that the damages produced by each pigeon in the urban area cost about 30 euros per year. If we multiply it by the number of pigeons in Barcelona, which in 2006 exceeded a quarter of a million, we will easily understand that it is an investment with a great economic and health benefit.