Swallows and swifts are the symbol of the beautiful season. But for thirty years, their presence has become rarer, in town and in the countryside. The problem concerns several species of migratory birds.
Spring is a blue sky streaked with swallows. The end of summer, flocks of birds ready to take the road again towards the warmer countries. The beautiful season can be recognized by the good weather and the scent of flowers in the air, as well as the chirping of these little birds and their nesting boxes on the walls of buildings, under all roofs. It’s a summer idea that speaks to our imagination, but which could soon be a thing of the past. In 2019, the National Museum of Natural History, in collaboration with the LPO, published a detailed monitoring of the presence of 123 bird species in France, based on data collected in thirty years of work. This document, the STOC (Temporal monitoring of common birds), speaks clearly: of the 123 species of birds identified, 43 are regressing, sometimes significantly, in the countryside as in the city.
In question, human action
This category also includes the common swift (-46.2%) and the house swallow (-23.2%), the most common in urban areas. The causes of this decline are known. As Ghislain Riou, ornithologist from the Nature association in Occitanie explains, “Swallows and swifts have fewer and fewer places to nest and it is increasingly difficult to find mud to build their nests in town. Moreover, despite the fact that it is forbidden, their nesting boxes are often destroyed. Renovation work on buildings, such as facelifts, and the artificialization of urban environments make their survival more complicated. This year, the peaks of heat added a particular difficulty to the survival of these birds: “Unlike the swallow, continues Ghislain Riou, the swift often makes its nest under the roofs of dwellings. It therefore suffers much more from the summer heat. With the high temperatures this year, their nest boxes quickly become unlivable and push the young to come out, when they are not ready. » The heat has a negative impact on the diet of swallows and swifts: insect populations are reduced due to the drought and the birds lack protein, essential for reproduction, for survival and for migrating at the end of summer.
Human action, the only solution
Although the assessment drawn up by the STOC seems negative, solutions exist: “Individuals can act in different ways, explains Ghislain Riou. “They can use a particular plaster for their exterior walls, which allows the mud from the nesting boxes to adhere better, plan renovations when migratory birds are not there, or even avoid mowing the lawn regularly. Indeed, a simple patch of wild grass promotes biodiversity and therefore the presence of insects.
Some town halls are also taking part in the efforts, by installing artificial nesting boxes. However, these actions are still far from being sufficient to solve a problem which is growing on a European scale.
These birds that proliferate in France
While some common birds are struggling to survive in town and country, others are proliferating. Unfortunately, this is not good news. The rock pigeon (+138.8%), the jay oaks (+23.2%), the blue tit (+14.6%) or the blackcap (+29.6%) belong to the so-called “generalist” species. Their increase therefore generates a standardization of wildlife, to the detriment of so-called “specialist” species. This trivialization leads to a long-term loss of biodiversity. Although the situation in cities is tragic (-27.6% of specialist birds in urban areas), the most significant drop in specialist birds is recorded in agricultural areas ( -29.5%), due to insecticides and intensive agricultural practices implemented in recent decades.