They weigh just 20 grams and their appearance is extremely delicate. But they return every year to the Iberian Peninsula after traveling more than 5,000 kilometers, from the Gulf of Guinea, in Africa, where they spend the winter. They have flown almost without rest over the Sahara desert and the Mediterranean Sea and have withstood water and sand storms. A single couple feeding their young can eliminate up to 1,700 flies and mosquitoes per day. There is no more effective and ecological insecticide. They are the swallows, which return to Europe to reproduce, announcing spring.
The barn swallow (hirundo rustica) one of the best known and best studied birds. The species has been key to unraveling aspects of migration, sexual selection and reproduction in birds. Due to their proximity to man throughout history, they form part of popular culture, and their arrival, increasingly earlier as a result of the climate changeis considered an announcement of good weather.
Despite its abundance, It is a species in decline, mainly due to changes in the rural environment and agricultural policies and techniques.as stated in the ‘Guide to Birds’ by SEO/BirdLife, an organization that designated it ‘Bird of the Year’ in 2014.
Although it is not a threatened species, it faces serious problems for a few decades, as “the indiscriminate use of pesticides, which reduce the amount of insects, on which it feeds; the deliberate removal of nests with the excuse that they dirty; the difficulty nesting in new rural buildings; and the abandonment of rural spacewith the consequent ruin of many buildings”, says SEO/BirdLife.
Species “of special interest”
In the National Catalog of Endangered Species, the barn swallow is listed as ‘Of special interest’. It is the most widespread member of its family, since it breeds in much of North America and Eurasia, except in arctic areas and deserts. In winter it occupies South America, Africa, southern Asia and northern Australia. Eight subspecies are recognized, although it has been suggested that some of these could be different species, especially the American forms.
As stated in the SEO/BirdLife ‘Guide to Birds’, the subspecies rustica is the only one present in Spainalthough sometimes reddish-bellied birds are seen that could belong to subspecies from the Middle East (transitiva, savignii) or simply be local variants.
It’s found widely distributed during the breeding season and in transit throughout the Peninsula, the Balearic Islands, Ceuta and Melilla. It winters in very small numbers in the south, mainly in the lower Guadalquivir. In the Canary Islands, where it is common in passage, it has recently been located breeding in Gran Canaria.
Spanish swallows winter in the Gulf of Guinea. and they gradually return to the breeding area, with a lag of up to three months between the north and the south. In Andalusia and Extremadura they usually begin to be seen in January, with a massive arrival from February; in the center and east of the Peninsula they usually do so a month later, and in the northern Meseta and the Cantabrian coast they do not become common until April. By this time it is already present throughout mainland Spain.
They usually leave the breeding areas from July, in the south, until the beginning of September, while the specimens in passage usually move, following the Mediterranean coast, in September and October. From June they gather in roosts, formed at first mainly by juveniles.
One million couples in Spain
Although the Spanish population has not been accurately quantified, it could have over a million couples. In fact, roosts with more than 100,000 birds are known. In Europe there are between 16 and 36 million couples. But between 1980 and 2003 the species suffered a serious decline, with an estimated 27% population loss on the continent.
This little bird, very social and monogamous, nests preferably in rural and urban constructions, such as stables, porches, patios and terraces, although in the south of the Peninsula some swallows live in rocky desert valleys. The most consumed prey are flies and mosquitoes. It also hunts flying ants, wasps, bugs, and small beetles.
The breeding season is from May to August., a period in which two incubations take place, each lasting 14 to 16 days. They lay 3 to 6 eggs. They are able to eat, drink and feed their chicks without stopping to fly. The young remain in the nest for 20 to 22 days. It breeds up to 1,600 meters of altitude. Only the female incubates.
Once the breeding season is over, swallows, young and adults, often by the thousands, gather to sleep in appropriate places, generally reedbeds, to which other related species also go, before embarking on their migratory flight. The main predators of the swallow are the seagull, the owl, the falcon and the domestic cat..
The expected penalty for knocking down nests of any species of swallow can reach 200,000 euros. Both Spanish and European legislation condemn it as a ‘serious offence’ to cause any type of damage to these birds and their nests, whether they are occupied or not.
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