Bird Conservation International

Research Article

Status and habitat changes in the endangered Spanish Imperial Eagle Aquila adalberti population during 1974–2004: implications for its recovery

Luis Mariano Gonzáleza1, Javier Oriaa2, Roberto Sáncheza3, Antoni Margalidaa4 c1, Antonio Arandaa5, Luis Pradaa6, Javier Calderaa7 and José Ignacio Molinaa8

a1 Dirección General para la Biodiversidad. Ministerio de Medio Ambiente, c/ Rios Rosas, 24, E-28005 Madrid, Spain

a2 Boscaje S.L, c/ San Agustín 22, E-40001, Segovia, Spain

a3 TRAGSA, c/ Velázquez 36, Madrid, Spain

a4 Bearded Vulture Study and Protection Group, Apdo. 43. E-25520 El Pont de Suert, Lleida, Spain

a5 Junta de Castilla-La Mancha, c/ Pintor Matías Moreno, 4, 45071 Toledo, Spain

a6 Consejería de Medio Ambiente, c/ Princesa 3, Madrid 28008, Spain

a7 Junta de Extremadura, Apdo. Correos 7, 10181, Sierra de Fuentes, Cáceres, Spain

a8 Junta de Castilla y León, c/ Rigoberto Cortejoso 14, 47071 Vallodolid, Spain

Abstract

The distribution and abundance of Spanish Imperial Eagle Aquila adalberti populations between 1974 and 2004 were determined using information from national censuses. Its breeding area occupies the south-western quadrant of the Iberian Peninsula (Spain and Portugal) and is composed of 13 nuclei and 5 subpopulations. Since 1974, population levels in all nuclei, except the one in Doñana, have expanded. The non-breeding dispersion area, according to sightings of juvenile and immature individuals in quadrants of 10 x 10 km, coincided with that of the breeding area. Bibliographical information showed that halfway through the 19th century the Spanish Imperial Eagle was considered abundant, at least locally; and most cited breeding areas were in relatively human-occupied plains. Towards the end of the 19th century the population became scarce; remaining so for most of the 20th century, with remote mountain ranges being the most cited breeding habitats. The comparison between the data from the first census, in 1974, that located 38 territorial pairs, and the 2004 census that located 198 pairs, shows that: 1) percentages of pairs in plains have increased, while those in mountains have decreased; 2) the trophic quality of the habitat, based on rabbit abundance, has decreased, and 3) numbers of nests in both protected areas and on private ground have increased significantly. The type of land ownership did not seem to affect breeding performance. Populations have increased more outside protected areas than within, despite the availability of potential habitat. In the past century, legal protection and attitude changes towards this eagle seem to have been influential in preventing its extinction. At present, habitat management seems also to be an important factor in its continuing recovery.

(Received January 25 2007)

(Revised September 24 2007)

Correspondence:

c1 Author for correspondance; e-mail: margalida@inf.entorno.es