Adult Eurasian griffons belonging to colonies located from Andalusia to French Pyrenees converge in the threatened Iberian "dehesas" to forage, after long-range forays up to 800 km. These are the results of a new study, recently published in the journal Scientific Reports and led by the Doñana Biological Station – CSIC. The Miguel Hernández University of Elche, the University of Seville, the Pablo de Olavide University, the University of Lleida, and the Basque Research and Technology Alliance have also taken part in the study, along with researchers from the University of Montpellier and the Parc National des Pyrénées.

The first author, Alejandro Delgado González, highlights that "this research is based on the dataset of adult Eurasian griffon vultures tagged with GPS. The five areas of study and the number of tagged individuals, more than 100, makes this project the most ambitious about movement Ecology carried out in Europe with scavengers". Because of its size and abundance, Eurasian griffon has an important role as a provider of key ecosystem services, such as the elimination of livestock leftovers at zero cost for exploitation owners. That's why it is interesting to know how these vultures move and which factors define their movements.

The results, based on the huge amount of information provided by the devices (more than 142 million locations) dismantle the popular belief that griffon vultures do not move far from their colonies. This study shows how individuals can travel hundreds of kilometers to settle during variable periods in different areas in Extremadura, Castilla la Mancha and western. Then they return to their original colonies. Very interestingly, these movements involved more females than males, even with fledglings in the nests, which are left in charge of their partners. 

Vultures from the five populations studied (French Pyrenees, Catalan Pyrenees, Ebro Valley, Cazorla, and Cadiz) have converged in the same region of the south-western Iberian Peninsula. Analyses show that "dehesas" determine the attraction and convergence of these birds in the region. "Dehesas" have diverse traditional uses where oak trees, grass, agriculture, and Mediterranean species gather, are extremely rich in biodiversity and have different, abundant, and attractive food resources. This is due to the extensive livestock farming practices and the more permissive sanitary laws that force owners to leave dead animals available for birds. Additionally, wild ungulate populations increased in Mediterranean ranges, which provide resources thanks to natural mortality and big game hunting.

Ainara Cortés-Avizanda and José Antonio Donázar, directors of this research, conclude that "dehesas are good examples of how traditional human economies favor the maintenance of large spatial-scale processes, which may be key to maintaining functions and services within ecosystems. Future conservation strategies for Iberian "dehesas" must consider the existence of organisms coming from distant regions, so any approach must be transboundary between regions and countries". 

Reference:

Delgado-González, A. et al. (2022). Apex scavengers from different European populations converge at threatened savannah landscapes. Scientific Reports 12, https://doi.org/10.1038/s41598-022-06436-9