They are still punctual, but they come in less abundance. Source of inspiration for poets, the bird that announces the arrival of spring, the unruly and noisy companion in rural houses or barns, is seen again; but their populations are declining. The barn swallow, the most common, is suffering serious declines. The number of specimens decreased by 24.8% in Spain between 2002 and 2021, according to data from the Spanish Society of Ornithology (SEO/BirdLife), which continues to demand measures for its conservation.
This year, in Catalonia, the two main species show a British punctuality. “They have arrived on the right dates,” says Xavier Riera, an expert at the Institut Català d’Ornitogia. Barn swallows (Hirundo rustica, black in color, with metallic blue reflections above) began to be seen this year the week of February 19 to 25, while the smaller house martin (Delichon urbicum) is becoming increasingly popular. letting it be observed a little later than it should be. “The barn swallow arrives all at once, while the house martin arrives in stages,” says Riera.
Swallows come from sub-Saharan Africa. Their diet based on insects moves their comings and goings, from one country to another, fleeing winters without insects.
They are insectivorous species and their migration cycles are synchronized to be able to go north in spring to witness the massive irruption of insects in spring. However, many specimens stay in the south of the Iberian Peninsula; and in Catalonia (where there are five species of swallows) the rock martin (“roquerol” in Catalan) also remains a resident. which breeds in the mountains and goes down to the wetlands in winter (Llobregat delta, Ebro delta), where they get the insects they are looking for.
Seeing them resting on ledges or cables, no one would guess that they move between Europe and West Africa making journeys of 3,000 kilometers, completed in journeys that are not always linear and regular, in stages of up to 100 kilometers in a day (which they can rectify by going south), so that they can total distances of 7,000 kilometers.
But the thousands of volunteers spread across the Peninsula who monitor them warn of the decline of the barn swallow: 24.8% in Spain as a whole between 2002 and 2021, although this decline has slowed to a figure of 9.2%. in the last 10 years, says Juan Carlos del Moral, BirdLife SEO expert.
A host of factors explain this decline, most of them related to the abandonment of the rural world and the loss of their favorite places to build nests, which have been abandoned or destroyed. The disappearance of agricultural and livestock activities, to which swallows were linked, has caused the loss of the insects that served as food.
“The farrowing pens, where the cattle were kept extensively, have been lost; and it must be taken into account that when these cattle moved they obtained a great source of insects. Now the cattle are clean, there are insecticides and all of this means that they no longer have as much food,” says Del Moral. The barns, stables or areas for extensive livestock have been renovated, replaced by an architecture that eliminates appropriate places for them to nest.
And the intensive use in the field of insecticides and other chemical products that reduce the reproductive capacity of this small bird also plays a role.
It is estimated that in Spain there are between 8.5 and 9.5 million barn swallows, so the decline in these two decades has meant a decrease of about 150,000 specimens per year.
However, in Catalonia the situation is not so unfavorable. The common swallow has decreased by 1% between 2002 and 2022, while in the most recent period (2013 to 2022) it has decreased by 3%. Its population is between 306,000 and 417,000 couples. And, for its part, the common plane has increased its populations by 4% if the long term (2022-2022) is considered and remains stable in the short term (2013-2022). They number between 75,000 and 150,000 couples.
On their return, the swallows demonstrate an enormous instinct to locate the area where they bred the previous year, a fidelity that is not so much to the nest as to the breeding area.
The Spanish poet Gustavo Adolfo Bécquer said it in an unsurpassable way: “The dark swallows on your balcony will return to hang their nests, and once again with their wings to their windows, they will call playfully.”
The common swallow breeds on the outskirts, in barns, garages, porches, haylofts and other non-residential buildings that have open doors, while the common house martin makes its nests inside urban centers hooked under the overhangs of roofs and balconies. .
However, the deliberate destruction of nests has become another major danger. The nests produce excrement and that is why it is common for homeowners to eliminate them. “But eliminating the nests is giving up the great benefits that these animals provide,” says Xavier Riera, recalling that they are great devourers of insects. They are great allies against flies and mosquitoes, always annoying.
In Catalonia, both the barn swallow and the house martin are protected, as are their nests, which cannot be broken “even in winter.” Therefore when the swallows return to Africa at the end of summer and leave the houses, the nests cannot be destroyed.
The Orenetes project, run by a legion of ICO volunteers, has inventoried and located many of the nests in buildings in Catalonia. It is as if they indicated the address of their “home”. Each nest that a volunteer from the “Orenetes” project hangs on the portal created for this purpose is proof. So that they continue to be punctual; and more come.
