The Iberian imperial eagle, undoubtedly the most emblematic bird of prey in Spain, was literally on the verge of extinction. In the 60s there were only 30 couples left in the entire Peninsula. However, today, thanks to the efforts of both institutions and experts and citizen groups, there are already more than 100 couples in Castilla y León alone, according to the latest data. That figure, added to the rest of the country, consolidates the recovery of this species.
The latest data indicates that Castile and Leon has notably increased in recent years its breeding population of imperial eagle, going from counting 29 pairs of this species in 2005, to 101 in 2020.
As reported by the Ministry of Development and Environment, the strong population increase in recent years has been accompanied by a notable increase in the area of distribution, having registered in 2020 for the first time its presence as a reproducer in the province of Palencia.
The Monitoring Plan of the State of Conservation of Biodiversity in Castilla y León establishes as one of its objectives the annual monitoring of the imperial eagle populations throughout its distribution area in Castilla y León with the aim of evaluating the trend of both the area occupation of the species, as well as the size of the population.
As a result of this work, the census of the species for the year 2020 was carried out and 101 territories were counted in Castilla y León in which there was a presence of this species; territories distributed between the provinces of Segovia (45 territories), Ávila (33 territories), Valladolid (15 territories), Burgos (3 territories), and in Zamora and Salamanca, with two territories in each province.
Also, charge Of special importance is the first record of a breeding pair of the Iberian imperial eagle in the province of Palencia.
During this census, a complete monitoring of reproduction was carried out in 99 pairs of imperial eagles and it was found that the laying rate was very high, confirming the laying of eggs in 94 percent of the territories.
Productivity was estimated at 1.5 chickens per pair, with a reproductive success of 1.62 chickens per pair with laying. In addition, the 85 couples that have had chickens have raised a total of 151 flown chickens, so the flight rate has been 1.78 chickens per couple.
45.5 percent of the 101 territories of Castilla y León with the presence of breeding pairs of the species are located in some Special Protection Area for Birds, highlighting the Sierra de Guadarrama SPA, in Segovia, with ten territories, and the ZEPA Valles del Voltoya and la Zorita, in Segovia, with ten.
More and more territories with imperial eagle
With the data from this latest census of the imperial eagle of 2020 in the Community, it can be verified that the trend of the species in the last twelve years has gone from 40 territories in 2009 to 101 territories in 2020, representing an increase of 152.5 percent.
Ávila has significantly increased its population, from 21 pairs to 33 territories and the population of Segovia has increased from 19 pairs to 45. In addition, the species it has colonized the provinces of Valladolid, Salamanca, Zamora, Burgos and Palencia as nesting sites.
For its part, the long-term evolution of the imperial eagle population in Castilla y León is also very positive. The species suffered a strong crisis that took it to historical lows in the 70s of the last century.
Later, in the 90s, around twenty couples were registered, with high mortality and low productivity. However, the effect of the numerous conservation measures that were implemented in the following years, led to a rapid recovery, passing through 29 pairs in 2005, 46 pairs in 2010, 74 in 2015 and up to 101 in 2020.
The strong population increase in the last twelve years has been accompanied by a notable increase in distribution area, going from having breeding pairs in 33 10×10 km UTM squares in 2009, to 75 squares in 2020, which represents an increase of 127.3 percent.
Despite the notable increase in the number of imperial eagle individuals in recent years and the increase in its range, its main pressures and threats continue to significantly affect the population.
The most relevant cause of mortality is electrocution in power lines, while other more common causes have lost relative importance in the past, such as poisoning and death from gunshots.
This is the imperial eagle, exclusive to the Peninsula
The Iberian imperial eagle, Aquila adalberti, has a worldwide distribution area limited to the center and west of the Iberian Peninsula. It is one of the species with the highest degree of threat in the world, and with a very reduced area of distribution, even more so after its extinction in North Africa.
It occupies Mediterranean forest habitats and its presence depends, to a great extent, on the abundance of its basic prey. In general, it avoids highly humanized areas to nest, although in recent years it has been colonizing areas with a higher degree of anthropization.
The reproductive adults are sedentary, but the young individuals, when they become emancipated, disperse through different areas of the Peninsula and it is common for some individuals to cross the Strait of Gibraltar towards Morocco, even reaching Senegal.
The application of effective conservation measures, such as the modification of dangerous power lines, the provision of supplementary feeding to the reproductive pairs, the monitoring of nests with special conservation problems, the protection of reproduction and feeding areas, the adequate management of forestry work in the environment of the nests and the recovery of rabbit populations have led to an increase in the population, and the colonization of new breeding areas.
In addition to the conservation measures, an exhaustive monitoring has been carried out during the breeding seasons, which has made it possible to know precisely the evolution of the population.
The Iberian imperial eagle is included in the Spanish Catalog of Threatened Species with the category of Endangered (Royal Decree 139/2011), and in Annex I of the Birds Directive (Directive 2009/147 / CE). It is listed as “vulnerable” worldwide in the document The 2000 IUCN Red List of Threatened Species (exposed to a high risk of extinction in the wild), and in the Berne Convention on the Conservation of Wildlife and the Natural Environment in Europe, it is located in Annex II referring to strictly protected species.