Home Sciences The swallow, in danger: every year a million disappear in Spain

The swallow, in danger: every year a million disappear in Spain


Climate change is causing a drastic decrease in the populations of bird species such as the barn swallow (hirundo rustica). SEO/BirdLife estimates that each year a million specimens of this emblematic species are lost in Spain, one of the most appreciated by citizens. In the rest of Europe, the situation is even worse.

The population decline of the barn swallow is alarming: was 41% between 1998 and 2012 and stands at 33% in the last decade. In addition, there is a 10% chance that the species will become extinct in the Iberian Peninsula in the next hundred years, according to a report by the NGO. Despite all this, at the moment, the swallow is only listed as a threatened species in four autonomous communities: Andalusia, the Balearic Islands, Castilla-La Mancha and Extremadura.

One of the criteria considered by the International Union for Conservation of Nature (IUCN) to classify species in the different threat categories is precisely the rapid population decline. And this is one of the values ​​that can be detected thanks to the data obtained in the Sacre common bird tracking program from SEO/BirdLife.

“Shrike, Quail, Western Jackdaw, Barn Swallow, Little Owl, Little Lark and Dartford Warbler are species that, like the Little Little Bustard, should be listed at least in the ‘vulnerable’ category as their populations have fallen by more than 30% in the last 14 years”, points out the NGO in its report ‘Trend in common bird populations in Spain (Sacre programme) 1998-2020’.

Of all these species, only the gray shrike is cataloged in Spain as ‘near threatened’, while the jackdaw, the swallow, the little owl, the lark and the dart-tailed warbler have not even been evaluated.

One of the factors that is influencing the decrease in barn swallow populations is the rural depopulation, since it implies the abandonment of their breeding places, usually linked to agricultural environments. Her decline led SEO/BirdLfe to declare her ‘Bird of the Year 2014’.

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In cities, the main problem is that modern buildings barely have holes and corners in which this and other species of birds can build their nests.

In addition, the use of insecticides, pesticides and other chemical products are affecting the reproductive capacity of swallows and eliminating a large part of the insects they feed on. A single swallow consumes 850 flies and mosquitoeswhich is more than 310,000 a year.

They arrive at our homes after traveling 5,000 kilometers

“That a swallow weighing 18 grams, which has just arrived from the Sahel, crossing the Sahara and traveling 5,000 kilometerschoose the house of a human to breed is a privilege and a gift from Nature”, underlines biologist Nicolás López, Species Conservation technician and SEO/BirdLife delegate in Asturias, Castilla y León and Galicia, who calls the population to preserve their nests and take care of the eaves and corners where they are built.

López also proposes to star “helping gestures” towards swallowssuch as installing artificial nests or making it easier for them to access materials such as mud or straw to build them.

SEO/BirdLife’s assessments coincide point by point with different scientific studies carried out in recent years, such as the one published in 2017 by Carlos Cano Barbacil and Javier Cano Sánchez on “Effects of climate change on birds”.

That report warned of behavioral changes in many species, such as the anticipation of migratory phenology, alterations in geographic distribution and, the most serious of all, the risk of species extinction.

“Precursors of climate change detection”

The conclusion of the two Spanish scientists was that global warming is “a great threat to the planet’s ecosystems”, but they also stressed that birds can be seen “as precursors of the detection of climate change”.

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Because climate change is also causing the early migration of swallows: they currently arrive in Spain four weeks in advance compared to what happened in the middle of the last century.

Another effect of climate change: an increase in the number of trans-Saharan migratory birds that stay in Spain for the winter has been recorded for years. In the case of the barn swallow, this behavior has increased remarkably over the last decade.

SEO/BirdLife points out that the mechanisms by which migratory birds such as the swallow can adapt their cycles to new climatic conditions are the advance in the beginning of migration, the increase in the speed of migration and the reduction of the migration distance. .

But the adaptations of species require time and some scientists predict that European species that do not manage to advance their life cycles sufficiently to the new scenario will suffer declines in their populations. This could already be happening with the swallows.

Birds and Weather Program

Hence, the record of phenological observations is extremely important for the future of species such as the barn swallow. The Birds and Climate program of SEO/BirdLife collaborates in the knowledge of the consequences of climate change on fauna and flora, and offers tools to collaborate, each one to the extent possible, to alleviate this “planetary problem”.

Birds and Climate, which has mobile phone applications, allows recording observations about when the first swallows arrive, when the almond trees bloom or on what date the first bees are seen flying. These are data that provide invaluable information, which allows us to know how climate change affects living beings.

Sacre program: https://www.seo.org/wp-content/uploads/2012/04/Resultados_generales_sacre_121.pdf


Environment section contact: crisisclimatica@prensaiberica.es

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