The rush of everyday life in cities causes most people to walk the streets without paying attention to the wildlife that inhabits urban areas. But if one demands to stop to observe and reflect how long it has been since you have seen a sparrow perched on a branch or looking for crumbs and fighting them with the ineffable pigeons, you may notice that years ago they were more abundant.
Something similar is happening in Europe and several studies have analysed the matter. To give a quick summary of the conclusions, it can be said that the experts detected that, it is true, sparrow populations are declining in some places, but it is not widespread and, in part, it is a migration to areas that are more friendly and less polluted than modern cities by which, what many may consider a progressive disappearance of the species, is simply a change of habitat.
Studies such as that carried out by the Cavanilles Institute of Biodiversity and Evolutionary Biology in Valencia, Spain, observed that although there has been a decrease in the number of sparrows in the last 15 years in that country and other parts of Europe, it is a small fall, and in some cases it has recovered.
However, as reported by Muy Interesante, the causes of the decline can be found in the changes that occurred in recent years in the urban centers where the species lived.
According to the organization SEO/Birdlife, “some of the main threats to birds in our cities are the lack of places to nest and shelter, the poor quality of their food, pollution, collisions with glass, or the reduction of green areas”. That is why in recent years it is promoting the “naturalization of cities” so that “urban planning does not lead us to the absolute decline of these birds”.
Like all species, an essential condition for the sparrow is that it can find food in the habitat it chooses. In particular, these birds opt for open sectors, with the presence of vegetation. This is causing cities that destroy their green spaces no longer have so many sparrows, the same is true of those areas where traffic has increased, which generates noise and pollution.
Sparrows nestled or settled in buildings, but they have moved away from areas where buildings are getting higher and higher because it offers them fewer areas of rest. What deepens this problem is that many people place tips on the cornices and other edges, often to scare away the pigeons, much more abundant, and thus avoid the damage caused by droppings. This also forces sparrows to migrate.
Another problem is the arrival in recent years of species that did not previously live in cities, either because of migration or the introduction of alien species by humans. In this way, sparrows encounter individuals who dispute their food and must maintain greater vigilance that increases their stress, according to a study by Imperial College London.
Thus, sparrow populations have escaped to other, more open areas, in some countries, directly, they have migrated to the countryside.
According to Muy Interesante, another cause has been reported, although it is still unknown whether it has a scientific basis, which is electromagnetic radiation. That media indicated that several scientific publications referred to the waves generated by mobile telephony. But the hypothesis has been questioned because there is no known harmful effect on birds of non-ionizing radiation until now and, in any case, if something like this were possible, it would have been observed many decades earlier with radio and television broadcasts.
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