The vultures fly hundreds of kilometers to feed, up to 800 one way and as many back, from the breeding areas of the Pyrenees to the dehesas of the southwest of the peninsula. They follow fixed paths, their aerial highways. “The one that passes through the south of the Sierra de Madrid is impressive, it’s like a stream of vultures going through a small space,” says José Antonio Donázar, researcher at the Doñana Biological Station (CSIC) and author of the study published in scientific report. Similar “kills” are stuck because in the meadows food abounds with a large number of remains of animals from extensive livestock, wild ungulates and hunting. “It’s as if it were a place of rest, their particular Benidorm, where they spend a few days relaxing and replenishing their strength,” says Donázar. Research has shown the importance of dehesas, an ecosystem endangered by climate change and the abandonment of traditional uses, for the long-term conservation of carrion birds and biodiversity. 90% of the population of griffon vultures in Western Europe (between 30,946 and 37,134 pairs, according to the SEO/BirdLife census) live in Spain and the south of France.
Researchers from the Doñana Biological Station (CSIC) and from Spanish and French universities have followed the adventures of 106 adult griffon vultures for seven years. The 70-gram GPS with which they are equipped sends information every minute, and they can even know if the ghouls are flying, eating, stopped…“. Some specimens move a lot and make five or six trips a year, there are even females that have chicks in the nest and leave them in charge of the male to return after four or five days. Others stay longer, to spend the summer”, describes Alejandro Delgado, first author of the work. Those who live further away – in the French Pyrenees, Lleida or in the Bardenas Reales (Navarra) – need a couple of days to travel to these open-air supermarkets. A behavior that, until now, scientists had only observed in seabirds such as albatrosses, which travel enormous distances to find schools of squid.
Dehesas are found in regions with mild, rainy winters and hot, dry summers. This landscape of oaks, meadows and scrub covers six million hectares (almost 10% of the surface of the Iberian Peninsula) in the southwestern regions. The vultures move through the pastures of Extremadura and Andalusia (by Sierra Morena, from Córdoba to Huelva), although they also use those of Salamanca and Ciudad Real. They take the opportunity to travel from May to October, when the rising currents of warm air make it easier for them to fly. In the case of females: “The reward must be very important to leave the chicken and make that investment of time and effort,” says Donázar.
The birds that come down from the Navarrese Pyrenees “take through Soria, pass through the mountains north of Madrid, continue through Gredos, from there to the north of Cáceres and direct to Extremadura, once there the highway ends and they diverge towards different places such as the Montes from Toledo, Sierra Morena… and some reach Cádiz and the Strait of Gibraltar”. The highway that passes through Madrid can be dangerous due to the collisions that can occur with planes. “We have held meetings with AENA to tell them that it is not only the specimens from Madrid that fly through that area, it is a continuous flow that can mean that dozens of specimens pass by every day,” he explains. Normally, they fly below 900 meters, most around 300.
The results of the study point to the importance of Mediterranean dehesas for the management and maintenance of vultures throughout their range in Western Europe. This behavior must be taken into account in the European strategies for the conservation of the species, which currently focus mainly on the protection of the breeding areas and on providing them with food at the points enabled for this, indicates the research. It is not taken into account that these animals move over much larger areas. In addition, the food found in nature “offers many advantages, both from an economic and health point of view, because it is healthier meat, from extensive livestock and wild animals.” The scientists also suggest that the Iberian dehesas may be promoting that the populations of western Europe can connect in these places, which could improve their viability.
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