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This species qualifies as Vulnerable because it has a very small population, which is dependent on ongoing intensive management measures to mitigate the impact of threats such as poisoning, electrocution and insufficient food availability.
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 and Málaga (González 1996b). 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), and in 2007 there were 232 breeding pairs in Spain and three in Portugal (Sánchez et al. 2008). The estimated population size has increased annually in Spain since 2000, and the species has recently recolonised Portugal (three pairs). Some of these increases can be attributed to more thorough searches within its range (notably in Andalucía), which is currently split into three subpopulations with relatively little interchange (González and Oria 2004).
Around 200 breeding pairs, some of which include at least one subadult bird (Grupo de Trabajo Nacional del Aguila Imperial Ibérica, unpubl. data, A. Madroño in litt. 2005), so an estimate of 300-400 mature individuals is appropriate. This roughly equates to 450-600 individuals in total.
The population has increased from as few as 30 pairs in the 1960s to 235 pairs in 2007 (Sánchez et al. 2008;González and Oria 2004; A. Madroño in litt. 2005).
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, 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 diet 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).
Electrocution is the primary cause of non-natural mortality for the Spanish Imperial Eagle recently, causing 50% of deaths according to recent studies (González et al. 2007). Juveniles are frequently killed through electrocution by powerlines, and this has been increasing in the last few years (L. M. González in litt. 2005). 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 as a result of viral haemorrhagic disease, and this is believed to have reduced breeding success (Margalida et al. 2007). In addition, changes in the management of hunting estates 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). 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 the current level of 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 power lines on private farms (Cabezas 2011). 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, landowners 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 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 (L. M. González in litt. 2005). Numerous young birds have been released as part of a reintroduction project in Cádiz (M. Pandolfi in litt. 2003), but no breeding pairs have yet become established in the province, and levels of mortality appear to be significant(B. Sánchez in litt. 2007).
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). 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)
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