Spanish Imperial Eagle Aquila adalberti


Justification of Red List Category
This species qualifies as Vulnerable because it has a very small population, which is dependent on continuing intensive management measures to mitigate the impact of threats such as poisoning, electrocution, shooting, collision with wind turbines and insufficient food availability. Having increased steadily during the end of the 20th and beginning of the 21st century, the population now appears to have reached a plateau.

Population justification
The species's global population is estimated at 530-540 breeding pairs, equating to 1,060-1,080 mature individuals (BirdLife International in prep.), which is assumed to be indicative of a total population of c.1,600 individuals.

Trend justification
The population has been increasing since recovery efforts started in the late 1960s (Mateos et al. 2021). It is estimated to have increased by c.167% between 2007-2018, with a long-term (1980-2018) increase of c.500% (BirdLife International in prep.), although the population now appears to have reached a plateau (S. Cabezas-Díaz in litt. 2020). The species recolonised Portugal in 2003, where it has been slowly increasing since, with six breeding pairs recorded in 2011, nine in 2012, 16 in 2016 and 17 in 2019 (S. Cabezas-Díaz and J. C. Atienza in litt. 2016; S. Cabezas-Diaz in litt. 2020).

Distribution and population

An Iberian breeding endemic eagle, most of the population breeds in Spain with a small but increasing population in Portugal. In Spain, breeding occurs in the Sierras of Guadarrama and Gredos, the plains of the Tajo, Tiétar, Guadiana and Duero rivers, the central hills of Extremadura, Montes de Toledo, the Alcudia valley, Sierra Morena, Campo de Montiel, the Guadalquivir marshes, the agricultural lands of Cádiz and in Salamanca, Valladolid, Zamora and Burgos (González 1996; S. Cabezas-Díaz and J. C. Atienza in litt. 2016; S. Cabezas-Díaz in litt. 2020). For the first time since the 1950s, a pair bred in 2016 in the Beticas mountains (J. R. Garrido in litt. 2016). 

The species recovered from a low of only 30 pairs in the 1960s to 38 pairs in 1970, and to around 200 pairs by 2004 (González and Oria 2004), despite a brief dip in the mid-1990s attributed to a viral haemorrhagic disease reducing rabbit populations (J. Criado in litt. 1999). The population has subsequently increased considerably, although it now appears to have reached a plateau (S. Cabezas-Díaz in litt. 2020). By 2020, the global population had increased to 530-540 pairs (BirdLife International in prep.). Portugal was recolonised in 2003 after an absence of breeding activity for over 20 years, and numbers have been slowly increasing since, with 16 breeding territories located in 2016 and 17 breeding pairs in 2019 (S. Cabezas-Díaz and J. C. Atienza in litt. 2013; S. Cabezas-Díaz in litt. 2020). Interchange of individuals has been noted between the populations in Portugal and in Andalucía. There is considerable variation in the rate of population increase throughout the range: In Extremadura, the increase was only c. 2% between 1990 and 2015 (S. Cabezas-Díaz and J. C. Atienza in litt. 2016), while in Andalucía the population has more than doubled since 2008 to 111 pairs (J. R. Garrido in litt. 2016). Improved adult survival appears to have driven the population increase and the observed temporal and spatial variation in population growth rates (Ferrer & Calderon 1990; Ortega et al. 2009). More recently, reduced adult survival appears to have caused a plateau in population size (S. Cabezas-Díaz in litt. 2020). Initial positive trends were associated with conservation measures, which reduced the mortality associated with powerlines and poisoning events, but also benefited the population through supplementary feeding, reparation of nests, reintroductions and reduction of disturbance during the breeding period (González et al. 2007, López-López et al. 2011, J. R. Garrido in litt. 2013, S. Cabezas-Díaz and J. C. Atienza in litt. 2016, M. Ferrer in litt. 2016, J. R. Garrido in litt. 2017). However, recently mortality caused by powerlines, shooting and collision with wind turbines has increased, and poisoning remains a threat (S. Cabezas-Díaz in litt. 2020). In Andalucía, a reintroduced population has been established in Cádiz, with four to five breeding pairs producing offspring, which have subsquently bred at several sites in southern Spain and in Portugal (Muriel et al. 2011, J. R. Garrido in litt. 2016). As a result of the improving fortunes of the species in Iberia, an increasing number of dispersing immature birds are being recorded in Morocco, where the species became extinct as a breeding species in the first half of the 20th Century (Thevenot et al. 2003, Maghreb Ornitho 2017). Six juveniles from the reintroduced population in Cádiz, which were satellite-tagged, later visited Morocco (Morandini et al. 2016). Immature birds have also been tracked travelling to Algeria, Mauritania and Western Sahara (Morandini et al. 2020). There is the potential for the re-establishment of a Moroccan breeding population, however mortality from electrocution appears exceptionally high in the country at present (Godino et al. 2016).


The species occurs in alluvial plains and dunes in the Guadalquivir marshes, plains and hills in central Spain, and high mountain slopes in the Sistema Central in Portugal. The abundance and distribution of rabbits, its favoured prey, influence population density, range and reproductive performance (Fernández et al. 2009). Indeed, its evolutionary dependence on rabbits has been suggested as permanently limiting its abundance and distribution (Ferrer and Negro 2004), although it may take alternative prey where rabbits are scarce in the non-breeding season (Sánchez et al. 2010). Breeding birds are sedentary, with median home range sizes of 28,000 ha during the breeding period and 10,500 ha in the non-breeding season (González and Margalida 2008). Within Doñana National Park, Spain, tree height and distance from human activity are the most important variables explaining nest site selection (Bisson et al. 2002), but many recently-colonised territories are located in human-modified habitat, especially farmland with high rabbit abundance (González and Oria 2004, Castaño 2005, J. R. Garrido in litt. 2016, González et al. 2006, Margalida et al. 2007).


The analysis of 267 records of non-natural mortality in this species over a 16-year period (1989-2004) showed an average rate of 15.1 individuals found dead annually, and that electrocution (47.7%) and poisoning (30.7%) were the most frequent causes of mortality (González et al. 2007). 40% of the cases were related to game practices and livestock protection, though most incidents were accidental (González et al. 2007). Mortality from intentional poisoning, which appears to be a particular problem in hunting reserves where game is commercially exploited, may once again be on the increase (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). 15 cases of death have been reported from poisoning events in 2015 - 2016 (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). This is of particular concern, as the dip in the population in the late 1990s was caused by additional mortality due to poisoning events, with the Doñana National Park population seriously affected by the illegal use of poisoned bait during this period (Ortega et al. 2009, Ferrer et al. 2013). Electrocution remains a significant source of mortality, despite mitigation measures leading to a highly significant reduction in the numbers of birds killed (Lopez-Lopez et al. 2011). This is a particular problem for immature eagles, and of six satellite-tagged individuals that visited Morocco in 2015 one was electrocuted, prompting the discovery of four further carcasses of immature birds near two recently installed high-voltage powerlines (Godino et al. 2016). Relatively few individuals are believed to have entered Morocco, indicating that powerlines may represent a serious threat to the potential re-establishment of a breeding population in the country. Despite the general success of mitigation measures applied in Andalucía (Lopez-Lopez et al. 2011), eleven individuals have been found electrocuted since 2010 (J. R. Garrido in litt. 2016). Several individuals have been found shot in the past decade in both Spain and Portugal (S. Cabezas-Díaz and J. C. Atienza in litt. 2016, J. R. Garrido in litt. 2016), suggesting that hunting remains a threat to the species. Additionally, the ingestion of lead shot embedded in the flesh of prey items may be a problem in certain areas (González and Oria 2004, Pain et al. 2005). The threats from poisoning and shooting highlight the importance of maintaining co-operation with landowners throughout the breeding range. In Spain, rabbit populations declined by 55% between 1973 and 2002 (Virgós et al. 2007). The incidence of viral haemorrhagic diseases and changes in the management of hunting estates has reduced prey availability. (Cabezas-Díaz et al. 2011). The intensification of farming through irrigation in parts of the range, coupled with increasing urban development, has reduced the availability and suitability of habitat in these areas and may constrain future population growth, with an increase in incidents of human conflict noted in these areas (J. R. Garrido in litt. 2016). The development of large areas of land for the production of renewable energy so far does not appear to have had negative impacts, however one individual was found dead in Andalucía in 2012 (J. R. Garrido in litt. 2016), and this threat may be increasing as more wind farms are being installed in many parts of the species's range (S Cabezas-Díaz in litt. 2020). Human activities in the vicinity of active nests can disturb incubating adults and reduce hatching success (González et al. 2006, Margalida et al. 2007). The limitation of funds for adequate monitoring and implementation of mitigation actions (particularly around the safety of powerlines for birds) may be a significant constraint in the future (S. Cabezas-Díaz and J. C. Atienza in litt. 2016).

Conservation actions

Conservation Actions Underway

CITES Appendix I and II. CMS Appendix I and II. EU Birds Directive Annex I. Raptors MOU Category 1. In Spain, 77 Important Bird Areas (IBAs) contain at least one breeding pair, and pairs occur in three IBAs in Portugal (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Around 60% of the total breeding population is now located in protected areas (national and EU Special Protected Areas), down from c. 70% in 2011 (Barov and Derhé 2011), which may reflect the growth of the population into new areas. Dispersal and critical areas for the species have not been updated for several years, therefore many are not legally delimited or protected against damaging activities (S. Cabezas-Díaz in litt. 2020). Since 1987, national and regional governments have been implementing a coordinated conservation plan for the species. A European action plan was published in 1996 and updated in 2008 (Sánchez et al. 2008). The national plan for Spain was implemented in 2018, while in Portugal a plan is being prepared (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Between 1991-1999, more than 14,000 dangerous electric pylons were modified in Spain, considerably reducing deaths from electrocution (González and Margalida 2008, López-López et al. 2011). As a result, a national law was approved in Spain in 2008, establishing tools for the protection of birds against collision and electrocution in power lines and best practice for new power line construction or modification (Guil et al. 2011).  Work has also been carried out to isolate dangerous power lines on private farms (Cabezas-Díaz 2011). In Portugal, the main potentially dangerous electric pylons have been identified in the core areas of the species and a modification plan has been established. Around 40 km of powerlines were modified between 2009 and 2011; however, around 80 km still require funding (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Isolation of power lines has been demonstrated to be obsolete in many cases (S. Cabezas-Díaz  in lill. 2020). A supplementary feeding programme has been established to mitigate the effects of rabbit decreases, and has significantly increased breeding success (González and Margalida 2008). Nest monitoring has reduced disturbance and improved reproductive success (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). The Soaring land stewardship network, which was created by SEO/BirdLife and the preceding Flying High Programme, for the conservation of Spanish Imperial Eagle lasted from 2006 to 2015 (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). This network involved 112 municipalities, 22,000 ha of private land and 96 schools, and focused on habitat management, species conservation, awareness raising and information activities across the whole distribution range in Spain (Cabezas-Díaz and Hernáez 2012). In Castilla-La Mancha, an EU LIFE-funded projected, "Conservación de especies prioritarias en el monte mediterráneo en Castilla-La Mancha" is working for the conservation of this and other species related to Mediterranean forests, while a counterpart project, LIFE Imperial, is focused on the conservation of the species in Portugal (R. Alcazar in litt. 2016). In Andalucía, a conservation programme was implemented, which includes hacking techniques for the reintroduction of the species, among other conservation actions (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Work is ongoing to raise awareness and support on private land where the species breeds, including improving habitat management (García 2007), and nearly 50% of breeding pairs are covered by such projects (González and Margalida 2008). In Cádiz, 73 young birds have been released as part of a reintroduction project (Ferrer 2011 unpubl.), and currently five breeding pairs have become established in the province providing a new population nucleus (Muriel et al. 2011). Birds originating from the reintroduction project in Andalucía are known to have bred in Portugal, Castilla-La Mancha, Sierra Morena and Doñana (J.R. Garrido in litt. 2016).

Conservation Actions Proposed

Continue with actions to reduce mortality, particularly from poisoning and electrocution (González and Oria 2004). Establish priority areas for powerline mitigation works and review the efficacy of those already corrected to inform best practice in mitigation and in the technical design of new pylons (Guil et al. 2011). Survey the breeding population annually. Approve regional recovery plans (González and Oria 2004). Maintain an adequate area of legally protected habitat (e.g. within the Natura 2000 network [González and Oria 2004]). Protect and manage breeding sites and key dispersal areas, including recently colonised areas not currently included within action plans (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Update dispersal and critical area distributions and use to update conservation plans at a regional scale. Continue the successful nest monitoring, supplementary feeding programmes and the stabilisation of nest at risk of collapse (Ferrer et al. 2017; González and Oria 2004; S. Cabezas-Díaz and J. C. Atienza in litt. 2016). Promote the recovery of the rabbit population (González and Oria 2004). Modify/ isolate dangerous powerlines (López and Cabezas-Díaz 2012).  Avoid the installation of wind farms in key areas for the species (S. Cabezas-Díaz in litt. 2020; B. Sánchez in litt. 2007). Avoid installation of solar power parks in feeding areas with important wild rabbit populations (S. Cabezas-Díaz in litt. 2020). Increase the coordination between private landowners, NGOs and government (González and Oria 2004, B. Sánchez in litt. 2007). Promote land stewardship for the conservation of the species and increase efforts to avoid persecution and disturbance (S. Cabezas-Díaz and J. C. Atienza in litt. 2016). 


75-84 cm. Large, dark eagle. Generally dark brownish-black with prominent white "shoulders" on forewing and scapulars. Pale golden-cream nape and pale grey basal area on uppertail. Juvenile red-brown fading to pale buff with dark flight feathers and white fringes to coverts. In soaring and gliding flight wings held flat. Similar spp. Adult Golden Eagle A. chrysaetos lacks white "shoulders" and is less dark overall. Immature has large white wing flashes and white base to tail. Wings held in a flattened "V" shape. Voice Repeated barking owk.


Text account compilers
Haskell, L.

Alcazar, R., Atienza, J., Balmori, A., Cabezas-Díaz, S., Caldera, J., Criado, J., Ferrer, M., Franco, A., Garrido, J., González, L.M., Izquierdo, E., Iñigo, A., Madroño, A., Montoro, J., Moreno-Opo, R., Nunes, M., Pacheco, C., Pain, D., Pandolfi, M., Sánchez, B., Sánchez-Aguado, F., Benstead, P., Pople, R., Taylor, J., Harding, M., Derhé, M., Ekstrom, J., Martin, R., Hermes, C. & Ashpole, J

Recommended citation
BirdLife International (2022) Species factsheet: Aquila adalberti. Downloaded from on 29/09/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from on 29/09/2022.