The population of Spanish black vulture It has been studied in various ways, with a long tradition in the study of its reproduction, its relationship with habitat and protected spaces, physiology, poisoning and its relationship with other anthropogenic effects.
There are also some studies of spatial ecology via satellite/GPS telemetry, but there is no exhaustive, large-scale study of area use by black vulture on the Iberian Peninsula, allowing us to clarify the patterns of population movements in detail.
The new monograph of the SEO/BirdLife Migra program Spatial behavior of the population of Spanish black vulture It includes the most detailed study to date on the movements of the species and attempts to answer numerous unknown questions regarding the movements of its populations.
From the distribution of juveniles to the occasional passage of individuals through the Strait of Gibraltar, or the differences in adult range based on sex between the breeding and non-breeding periods. The new monograph of the SEO/BirdLife Migra program Spatial behavior of the Spanish population of black vulture collects the most detailed study to date on the species’ movements.
“As a novelty, it should be noted that these results demonstrate for the first time that the Spanish black vulture “It is capable of performing migratory movements similar to those of other European gliding birds of prey,” said Juan Carlos del Moral, citizen science coordinator at SEO/BirdLife.
In addition to this detailed information in PDF format, the journeys of the tagged vultures can be consulted interactively on the bird migration website. In it you can visualize the journeys of all specimens, activate them and see how they progress over time, individualize them, view them in detail with different cartographic layers, set them at different speeds, with different line thicknesses, they can be converted to occupied geographical areas according to heat maps, etc.
Also from this website you can consult in the same system the journeys of 8 other species with similar analyzes and travel through them to consult more information about movements on other websites such as the European Migration Atlas, among others, and about the biology of birds such as the III Atlas of birds during the breeding season in Spain, red books on different geographical scales, bird guides and much more.
Data analysis of the Spanish black vulture
Thanks to the analyzes carried out by the research team of the University of Alicante, this study has information on 52 specimens of all age classes (adults, immature and chicks) and both sexes, distributed throughout the large colonies of the south-west of the Iberian area and points where they are recently reintroduced (northern Castilla y León and Catalonia).
These markers have enabled accurate spatio-temporal knowledge of the movements of individuals throughout their life cycle, including the dispersal of juveniles, the spatial ecology during the breeding and wintering seasons, migration routes, post-reproductive movements, territoriality, etc.
How does the Spanish black vulture behave during the breeding season?
The ecological needs of adult birds are different from those of young birds and so are their movements. One of the largest determinants of the movements of adult individuals is reproduction.
In the Spanish black vulture, the breeding period extends from February to September, which significantly conditions these movements. Adult black vultures (over 5 years old) remained more attached to the territory shared by the colony. Despite high variability and certain seasonal differences, adults generally repeat their campsites very frequently.
The parameter where the most differences between the different periods could be found lies in the accumulated monthly distance, that is, in the magnitude of the movements that take place. During the chickens’ breeding period, the total distance (11,035 ± 31,267 km2) practically doubled compared to the incubation and non-breeding periods. During these times, estimated ranges also increased slightly.
Behavior of young Spanish black vultures
Juveniles usually make dispersed movements over large parts of the territory. The data from 41 young black vultures (from infancy to subadult age, in the fourth year of life) generally showed large movements around their place of origin, often covering large parts of the Iberian Peninsula and southern Europe.
Typically, juveniles leave the parental territory a few weeks or months after leaving the nest to travel hundreds of kilometers before returning to it. This trend was gradually reduced as the age of the individuals increased, tending towards stability in immature and subadults.
In this way, spatial segregation is created in the Spanish black vulture depending on age, probably because the larger adults are the first to access the bait and the young have to move to places further away from the colony where there is not as much competition for the resource.
Females of all ages had larger campsites and greater distances to the nest, that is, females dispersed more than males. This circumstance, which also occurs in other similar species of Iberian vultures, such as the griffon vulture, may be due to the larger size of the females, which are forced to explore larger areas of the territory to obtain the necessary food, but also to the spatial segregation between genders, but also between ages.
The trans-Saharan journey of migratory chicks of the Spanish black vulture
Migration is a rare strategy among the population of Spanish black vulture, although it is common in other populations around the world. There was evidence of the annual passage of some individuals of this species through the Strait of Gibraltar during the migratory period. Nevertheless, the routes followed, the exact phenology and the wintering areas were unknown.
In this study, the trans-Saharan migration of two specimens from their native range in Spain to their wintering grounds in Senegal, in the westernmost part of the Sahel, is analyzed. The autumn migration lasted about a month, during which they covered a total of 4,032 and 4,980 km respectively (158 ± 85 and 146 ± 87 km per day).
This migration started in early November. They crossed the strait about the middle of the same month and reached winter quarters in Africa in early December. During the autumn migration, only two days of rest occurred for both vultures (without significant migratory movements).
Individuals wintered in the central and southern part of Senegal, alternating between silvopastoral reserves and the Saloum River delta area. Numerous species of European and African vultures are found in these areas, so it seems very beneficial for their development. One of the specimens died there and the other returned to Spain via a more westerly migration route than during the autumn migration (walking migration).
He did not return to his colony of origin, but stopped the migratory movement in the mountains of inland Cádiz after crossing the strait. It lasted another year, during which it carried out a dispersal similar to that of its immature counterparts that did not leave the peninsula, through areas of the inland mountain ranges of Cádiz, Sierra Morena or Extremadura.
“As a novelty, it should be noted that, given these results, they demonstrate for the first time that the Spanish black vulture is capable of performing strict migratory movements, comparable to those of other European soaring birds,” says Juan Carlos del Moral. , SEO citizen science coordinator. /BirdLife.
The case of two Spanish black vultures with signs for more than 10 years
“Two of the more than fifty examples marked with devices provided signals for more than ten years, while series of more than four or five years are usually not available. These two vultures facilitated the knowledge of their lives from the first days of their departure from the nest, their period of dispersal and distance from their parents and native territory, their movements during their childhood years and several years of their installation as breeders and adults in colonies that different from the one they were born into,” Del Moral acknowledges.
Migra program
“For the Iberdrola Spain Foundation, supporting entities related to the environment is very important; we strongly believe in the importance of understanding and conserving the habitat of these endangered species that play such an important role in the ecosystem. This collaboration is once again proof of Iberdrola’s commitment to bird conservation to preserve our natural heritage,” says Ramón Castresana, Director of the Iberdrola Spain Foundation.
Launched in 2011 by SEO/BirdLife in collaboration with the Iberdrola Spain Foundation, the Migra program incorporates the latest technologies in geolocation and remote monitoring systems to understand in more detail the movements of birds within and outside our country.
Thanks to this initiative it is possible to know the start and end dates of their migrations, the stopping points and feeding points, the time required to make these journeys, whether they are repeated during the spring and autumn migration, the main wintering areas and distribution , or whether the routes are the same year after year. The Iberdrola Spain Foundation collaborates with this program as part of its activities in support of biodiversity, one of its main areas of action.
The Migra program currently has 1,368 marked birds of 38 different species. These numbers are not just the result of specific marking work in the program itself; Much effort has gone into the program to establish agreements with other entities that provide data on marked birds.
With this information, numerous monographs have already been published to learn more about the movements of Audouin’s gull, booted eagle, Cory’s shearwater, Bulwer’s petrel, white stork, Eleanor’s falcon and red kite. Information is also available on the Bird Migration website, which contains interactive maps and numerous information on various aspects of migration and links to other ornithological information centres.