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Spanish Imperial Eagle Aquila adalberti

This species qualifies as Vulnerable because it has a very small population, which is dependent on on-going intensive management measures to mitigate the impact of threats such as poisoning, electrocution and insufficient food availability, as well as the increasing cooperation of land-owners.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _the_WP15.xls#.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

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.

Distribution and population
Aquila adalberti breeds in Spain in the Sierras of Guadarrama and Gredos, the plains of the Tajo and Tiétar rivers, the central hills of Extremadura, Montes de Toledo, the Alcudia valley, Sierra Morena and the Guadalquivir marshes, with occasional nesting in Salamanca (González 1996b). The species has not been recorded as breeding in Málaga province since at least the early 1970s (J. R. Garrido in litt. 2013). In the 1960s, only 30 pairs remained, but recovery began in the early 1980s at a rate of five new breeding pairs per year up to 1994. After 1994, the population again started to decline from 148 pairs to 131 pairs in 1998 (J. Criado in litt. 1999), and breeding success in important areas such as the Guadalquivir marshes declined dramatically in the late 1990s (J. Criado in litt. 1999). However, this is thought to represent a brief levelling out of a positive trend, and in 2000 the population began increasing (Grupo de Trabajo Nacional del Águila Imperial Ibérica unpubl. data; A. Madroño in litt. 2005), associated with a decline in the number of poisoning events (González et al. 2007). In 2007, there were 232 breeding pairs in Spain and three in Portugal (Sánchez et al. 2008). In 2011, the species's global population had increased to 324 pairs, with 318 pairs in Spain, of which 71 pairs were in Andalucía, increasing to 80 in 2012 (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013, J. R. Garrido in litt. 2013). The species recolonised Portugal in 2003, after an absence of breeding activity for over 20 years, and has been slowly increasing since, with six breeding pairs located in 2011 and nine located in 2012 (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013). The population in Spain showed an average annual increase of c.7% between 1990 and 2011, with the population in Andalucía increasing by c.8% per year on average over the same period (J. R. Garrido in litt. 2013). These positive trends are largely attributed to mitigation measures to reduce mortality associated with powerlines, supplementary feeding, reparation of nests, reintroductions and decreases in the disturbance of breeding birds (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013, J. R. Garrido in litt. 2013), although some of the observed increases may be due to more thorough searches within its range. This may be particularly true in Andalucía, which harbours three subpopulations (Sierra Morena mountains, Doñana National Park and a reintroduced population in Cádiz; González and Oria 2004, J. R. Garrido in litt. 2013), with interchange of individuals amongst these and with the population in Portugal (J. R. Garrido in litt. 2013).

Population justification
The species's global population was estimated at 324 breeding pairs in 2011, equating to 648 mature individuals (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013), and assumed to be indicative of a total population of c.1,000 individuals.

Trend justification
Over the period 1990-2011, the population in Spain showed an average annual increase of c.7%, with the population in Andalucía increasing by an average of c.8% annually over the same period (J. R. Garrido in litt. 2013). The species recolonised Portugal in 2003, and has been slowly increasing since, with six breeding pairs recorded in 2011 and nine in 2012 (S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013).

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 and other areas of Portugal, where there is an absence of irrigated farmland. 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 a recent study has suggested the species exhibits a certain dietary plasticity, at least during the non-breeding season, adapting its diet when rabbits are scarce (Sánchez et al. 2010). Data from Doñana National Park in Spain show that the most important variables explaining nest site selection are height of tree and distance from human activity (Bisson et al. 2002). Many recently-colonised territories are in marginal areas, and several of the occupying pairs include at least one sub-adult bird (González and Oria 2004, 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). Juveniles are frequently killed through electrocution by powerlines, and this has increased in recent years (L. M. González in litt. 2005). This remains the primary threat in Andalucía, with six birds found to have died this way in 2011 and three found dead in 2012 where mitigation measures had been attempted (J. R. Garrido in litt. 2013). Renewable energy development poses another potentially significant threat. Habitat fragmentation has occurred as a result of deforestation for agriculture and timber, having negative impacts on nest site preferences in particular. Suitable habitat in breeding and dispersal areas has also declined as a consequence of urban development and land-use changes (e.g. new irrigation schemes in Huelva [B. Sánchez in litt. 2007]). Mortality from intentional poisoning has risen sharply, particularly in hunting reserves where game is commercially exploited. Between 1990-1999, 57 birds died from poisoning and this is thought to be the primary cause of declines in the late 1990s (J. Criado in litt. 1999). In Doñana National Park in particular, the population has been seriously affected by the illegal use of poisoned bait, especially during the 1990s (Ortega et al. 2009). Rabbit populations have declined in both Spain and Portugal, as a result of viral haemorrhagic disease, and this is believed to have reduced breeding success (Margalida et al. 2007; S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013). In addition, changes in the management of hunting estates in both Spain and Portugal to favour larger quarry species, such as deer and boar, rather than rabbits and partridges, has further reduced prey availability (B. Sánchez in litt. 2007; S. Cabezas-Díaz, J. C. Atienza et al. in litt. 2013). In spring 2009, a male Spanish Imperial Eagle was shot and killed in Portugal, highlighting the current threat of hunting to this species. 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 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). Recent modelling suggests no subpopulations are currently at risk of extinction, provided that active management is maintained (L. M. González in litt. 2005).

Conservation Actions Underway
CITES Appendix I and II. CMS Appendix I and II. There are 24 Important Bird Areas identified for the species, 22 in Spain and 2 in Portugal. Altogether, there are 107 areas protected by Law (national and EU Special Protected Areas,) containing c.70% of the total breeding population (Barov and Derhé 2011). 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), and a national plan is being implemented. From 1991-1999, 14,370 dangerous electric towers were modified, considerably reducing deaths from electrocution (L. M. González in litt. 2005) and more recently, work has been carried out to isolate dangerous powerlines on private farms (Cabezas 2011). It is thought that nearly €2.6 million were spent on the mitigation of bird electrocution in Andalucía during 1992–2009, although not all mitigation measures have proved to be totally effective for this species (J. R. Garrido in litt. 2013). A supplementary feeding programme has been established to mitigate the effects of rabbit decreases, and has significantly increased breeding success (L. M. González in litt. 2005). Nest monitoring has reduced disturbance and improved reproductive success. The Flying High Programme created by SEO/BirdLife in 2006, begun its second phase in 2009 until 2012, based on a large land stewardship network (of municipalities, land-owners and schools). This network focuses on habitat management, species conservation, awareness and information activities covering the species’s entire distribution. So far, 54 municipalities have joined the network. Work is on-going 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 (L. M. González in litt. 2005). From 2002 to 2011, 73 young birds were released in Cádiz as part of a reintroduction project, and by 2012 five breeding pairs had become established in the province; however, mortality associated with powerlines appears to be high amongst these birds (M. Pandolfi in litt. 2003, B. Sánchez in litt. 2007, J. R. Garrido in litt. 2013). Nevertheless, the establishment of a breeding population in Cádiz further reduces the overall probability of extinction (Muriel et al. 2011). Two birds originating from a reintroduction project in Andalucía are known to have bred in Portugal (J. R. Garrido in litt. 2013).

Conservation Actions Proposed
Continue with actions to reduce mortality, particularly from poisoning and electrocution (González and Oria 2004). 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.  Continue the successful nest monitoring and supplementary feeding programmes (González and Oria 2004) and develop a captive breeding programme to support future reintroduction and supplementation efforts.  Promote the recovery of the rabbit population (González and Oria 2004). Modify dangerous powerlines.  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).

Related state of the world's birds case studies

Barov, B and Derhé, M. A. 2011. Review of The Implementation Of Species Action Plans for Threatened Birds in the European Union 2004-2010. Final report. BirdLife International For the European Commission.

Bisson, I. A.; Ferrer, M.; Bird, D. M. 2002. Factors influencing nest-site selection by Spanish Imperial Eagles. Journal of Field Ornithology 73: 298-302.

Cabezas, S. 2011. "Alzando el vuelo" sigue sumando apoyos. Aves y naturaleza: 36.

Collar, N. J.; Butchart, S. H. M. 2013. Conservation breeding and avian diversity: chances and challenges. International Zoo Yearbook.

Fernández, M.; Oria, J.; Sánchez, R.; Gonzalez, L. M.; Margalida, A. 2009. Space use of adult Spanish Imperial Eagles Aquila adalberti. Acta Ornithologica (Warsaw) 44(1): 17-26.

Ferrer, M.; Negro, J.J. 2004. The near extinction of two large european predators: super specialists pay a price. Conservation Biology 18: 344-349.

García, B. 2007. El programa 'Alzando el vuelo' trabaja ya en más de siete mil hectáreas. La Garcilla: 39.

González, L. M. 1996. Action plan for the Spanish Imperial Eagle Aquila adalberti. In: Heredia, B.; Rose, L.; Painter, M. (ed.), Globally threatened birds in Europe: action plans, pp. 175-189. Council of Europe, and BirdLife International, Strasbourg.

González, L. M.; Oria, J. 2004. Águila Imperial Ibérica Aquila adalberti. In: Madroño, A., González, C., Atienza, J.C. (ed.), Libro Rojo de las Aves de España, pp. 145-151. Dirección General para la Biodiversidad & SEO/BirdLife, Madrid.

González, L. M.; Oria, J.; Margalida, A.; Sánchez, R.; Prada, L.; Caldera, J.; Aranda, A.; Molina, J. I. 2006. Effective natal dispersal and age of maturity in the threatened Spanish Imperial Eagle Aquila adalberti: conservation implications. Bird Study 53(3): 285-293.

González, L.M.; Arroyo, B.E.; Margalida, A.; Sánchez, R.; Oria, J. 2006. Effect of human activities on the behaviour of breeding Spanish Imperial Eagles (Aquila adalberti): management implications for the conservation of a threatened species. Animal Conservation 9(1): 85-93.

Gonzlez, L. M.; Margalida, A.; Maosa, S.; Snchez, R.; Oria, J.; Molina, J. I.; Caldera, J.; Aranda, A.; Prada, L. 2007. Causes and spatio-temporal variations of non-natural mortality in the vulnerable Spanish Imperial Eagle Aquila alberti during a recovery period. Oryx 41(4): 495-502.

Margalida, A.; González, L. M.; Sánchez, R.; Oria, J.; Prada, L. 2007. Parental behaviour of Spanish Imperial Eagles Aquila adalberti: sexual differences in a moderately dimorphic raptor. Bird Study 54(1): 112-119.

Muriel, R.; Ferrer M.; Casado, E.; Madero, A.; Pérez Calabuig, C. 2011. Settlement and successful breeding of reintroduced Spanish imperial egales Aquila adalberti in the province of Cadiz (Spain). Ardeola 58(2): 323-333.

Ortega, E.; Mañosa, S.; Margalida, A.; Sánchez, R.; Oria, J.; González, L. M. 2009. A demographic description of the recovery of the vulnerable Spanish Imperial Eagle Aquila adalberti. Oryx 43(1): 113-121.

Pain, D.J.; Meharg, A. A.; Ferrer, M.; Taggart, M.; Penteriani, V. 2005. Lead concentrations in bones and feathers of the globally threatened Spanish imperial eagle. Biological Conservation 121: 603-610.

Sánchez, B., González, L., Barov, B. 2008. Action plan for the Spanish Imperial Eagle Aquila adalberti in the European Union. BirdLife International for the European Commission.

Further web sources of information
Action Plan

Detailed species account from Birds in Europe: population estimates trends and conservation status (BirdLife International 2004)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Explore HBW Alive for further information on this species

Jump to the case study for this species in Wildlife comeback in Europe: The recovery of selected mammal and bird species (Deniet et al. 2003)

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Derhé, M., Ekstrom, J., Harding, M., Pople, R., Taylor, J.

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

Recommended citation
BirdLife International (2014) Species factsheet: Aquila adalberti. Downloaded from on 29/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 29/07/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Spanish imperial eagle (Aquila adalberti) 0

Key facts
Current IUCN Red List category Vulnerable
Family Accipitridae (Hawks, Eagles)
Species name author Brehm, 1861
Population size 648 mature individuals
Population trend Increasing
Distribution size (breeding/resident) 117,000 km2
Country endemic? No
Links to further information
- Additional Information on this species