Spatial ecology and habitat use of adult Booted Eagles (Aquila pennata) during the breeding season: implications for conservation

Fast-moving technological advances, such as satellite tracking technologies, are providing in-depth information of aspects of avian ecology hitherto unknown. In fact, detailed information about movement ecology and ranging behaviour of birds is important not only from the perspective of the basic ecology, but also from the conservation point of view. This is particularly important in European countries where agricultural intensification, land abandonment and the withdrawal of traditional management agro-forestry practices pose a threat to biodiversity. The Booted Eagle, likewise other forest raptors, is an adequate bioindicator of human-dominated agro-forestry Mediterranean landscapes in which low-intensity traditional agricultural practices still persist. Here, using a combination of an unbiased technology (i.e., GPS telemetry), a wide geographic extension of marked birds (all over Spain), and much larger sample size than in previous works, we provide the first quantitative assessment of the home range size and space use of the Booted Eagle by means of GPS satellite telemetry during the breeding season. Interestingly, our results revealed different levels of space use over the breeding season and showed that eagles perform long distance foraging movements (i.e., >20 km) from the nest throughout the breeding season. This resulted in larger home ranges than reported thus far, and, more interestingly, in an extremely eccentric topology of territories. Hence, management measures for conservation of forest raptors based on setting restrictions around nesting sites using buffer areas of arbitrary radii clearly results in large areas of eagles’ home ranges laying outside “restriction” areas. Therefore, conservation measures should take into account the full range of agro-forestry habitats encompassed within the home range. Finally, our results support the claim that a large-scale management approach beyond the establishment of a closed network of protected areas such as the Natura 2000 network is necessary for the conservation of Mediterranean raptors.

All information about tagged eagles has been obtained in the framework of the ‘Migra’ project (http://www.migraciondeaves.org/en/) developed by SEO/BirdLife and funded by Iberdrola Foundation Spain. Pascual López-López is supported by a ‘Juan de la Cierva-incorporación’postdoctoral grant of the Spanish Ministry of Economy and Competitiveness (Reference IJCI-2014-19190).