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 and insufficient food availability, and on the increasing cooperation of land-owners.

Population justification
The species's global population was estimated at 485 breeding pairs in 2016, equating to 970 mature individuals (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016), and assumed to be indicative of a total population of c.1,450 individuals.

Trend justification
The Spanish population is estimated to have increased by 135% between 2001-2012, with a long-term (1984 - 2012) annual increase of 9.6% (BirdLife International 2015). The species recolonised Portugal in 2003, and has been slowly increasing since, with six breeding pairs recorded in 2011, nine in 2012 and 16 in 2016 (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016).

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 occasionally in Salamanca (González 1996, S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016). 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, with 38 pairs in 1970 rising 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. By 2015, the global population had increased to 485 pairs, 469 of which were in Spain (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016). 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 (S. Cabezas-Díaz, J. C. Atienza et alin litt. 2013), and interchange of individuals noted between this population and those in Andalucía. There is considerable variation in the rate of population increase throughout the range; in Extremadura the increase is only c. 2% between 1990 - 2015 (S. Cabezas-Díaz, J. C. Atienza et al. 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 be the driver of the population increase and the observed temporal and spatial variation in population growth rates (Ferrer & Calderón, 1990, Ortega et al. 2009). This positive trend is associated with conservation measures which have 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, J. C. Atienza et alin litt. 2016, M. Ferrer in litt. 2016). In Andalucía a reintroduced population has been established in Cádiz with four to five breeding pairs producing offspring which have subsequently 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). All six juveniles satellite-tagged from the reintroduced Cádiz population visited Morocco (Morandini et al. 2016). 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).


It 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 (Fernández et al. 2009) and reproductive performance. 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. 2006b, Margalida et al. 2007).


The analysis of 267 records of non-natural mortality in this species over a 16-year period (1989-2004) shows an average annual 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 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, J. C. Atienza et alin litt. 2016). 15 deaths have been reported from poisoning events in 2015 - 2016 (S. Cabezas-Díaz, J. C. Atienza et alin 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 (Ferrer et al. 2013, Ortega et al. 2009). 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). It is a particular problem for immature eagles, and of 6 satellite-tagged individuals that visited Morocco in 2015 one was electrocuted, prompting the discovery of four further carcasses of immature birds within the same small area near the intersection of two recently installed high-voltage powerlines (Godino et al. 2016). Relatively few individuals are believed to have entered Morocco, indicating that this may represent a serious threat to the potential establishment of a breeding population in the country once again. Despite the general success of mitigation measures applied in Andalucía (Lopez-Lopez et al. 2011), 11 eagles have been found electrocuted since 2010 (J.R. Garrido in litt. 2016). Several Spanish Imperial Eagles have been found shot in the past decade, in both Spain and Portugal (S. Cabezas-Díaz, J. C. Atienza et alin litt. 2016, J.R. Garrido in litt. 2016), suggesting 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 (Pain et al. 2005, González and Oria 2004). The threats from poisoning and shooting highlight the importance of maintaining co-operation with landowners throughout the breeding range.In Spain, rabbit populations declined a 55% between 1973 and 2002 (Virgós et al. 2007) because of several factors. The incidence of viral haemorrhagic and changes in the management of hunting estates to favour larger quarry species, such as deer and boar, rather than rabbits and partridges, has reduced prey availability (Cabezas-Díaz et al. 2011) and this is believed to have reduced breeding success of Spanish Imperial Eagle (Margalida et al. 2007), although as noted above it has been adult mortality driving population declines rather than productivity (Ferrer and Penteriani 2008).The intensification of farming through irrigation in parts of the range, coupled with increasing urban development has reduced habitat availability and suitability 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). Human activities in the vicinity of active nests can disturb incubating adults and reduce hatching success (González et al. 2006a, 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, J. C. Atienza et alin litt. 2016).

Conservation actions

Conservation Actions Underway
CITES Appendix I and II. CMS Appendix I and II. EU Birds Directive Annex I. In Spain, 77 Important Bird Areas (IBAs) contain at least one breeding pair, and pairs occur in three IBAs in Portugal (S. Cabezas-Díaz, J. C. Atienza et al. 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) reflecting the growth of the population into new areas. 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). A national plan for Spain is being implemented, while in Portugal the national action plan is being prepared (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016).  Between 1991-1999, 14,370 dangerous electric pylons were modified in Spain, considerably reducing deaths from electrocution (González and Margalida 2008, López-López et al. 2011). As a result, in 2008, in Spain, a national Law was approved 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 are identified on the core areas of the species and a modification plan established. Around 40 km of powerlines were modified between 2009 and 2011, however around 80 km still require funding (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016). A supplementary feeding programme has been established to mitigate the effects of rabbit decreases, and has significantly increased breeding success (González y Margalida 2008). Nest monitoring has reduced disturbance and improved reproductive success (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016). The Soaringland stewardship net created by SEO/BirdLife and the preceding Flying High Programme for the conservation of Spanish Imperial Eagle spanned 2006-2012 (S. Cabezas-Díaz, J. C. Atienza et al. 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 and information activities across the whole Spanish distribution (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 focued on the conservation of the species in Portugal (R. Alcazar in litt. 2016). In Andalucía a conservation programme was implemented that includes, among other conservation actions, hacking techniques for the reintroduction of the species (S. Cabezas-Díaz, J. C. Atienza et al. 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). 73 young birds have been released as part of a reintroduction project in Cádiz (Ferrer 2011, unpubl. data), 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, J. C. Atienza et al. in litt. 2016).  Continue the successful nest monitoring, supplementary feeding programmes and the stabilisation of nest at risk of collapse (González and Oria 2004, S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2016). Promote the recovery of the rabbit population (González and Oria 2004). Modify dangerous powerlines (López and Cabezas-Díaz 2012).  Avoid the construction of wind farms in key areas for the species (B. Sánchez in litt. 2007). Increase 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, J. C. Atienza et al. 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
Taylor, J., Derhé, M., Ashpole, J, Harding, M., Pople, R., Martin, R, Ekstrom, J., Benstead, P.

Sánchez, B., Pandolfi, M., Sánchez-Aguado, F., Garrido, J., Criado, J., Franco, A., Cabezas-Díaz, S., Caldera, J., Balmori, A., Nunes, M., Pacheco, C., Moreno-Opo, R., Izquierdo, E., Ferrer, M., Pain, D., Atienza, J., Iñigo, A., Madroño, A., González, L.M., Montoro, J.

Recommended citation
BirdLife International (2019) Species factsheet: Aquila adalberti. Downloaded from on 18/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from on 18/11/2019.