Conservation Biology Group

Threats and solutions


Owing to the information obtained from the study on Bonelli's Eagle, it is possible to conclude that the factors that threaten the survival of the species may be demographic,  derivatives of an imbalance between the losses of individuals of the population (mortality) and the number of produced chicks that come to the adult age; or they may have their origin in an alteration of their territories and habitats.

To solve the demographic imbalance and to guarantee the maintenance of the populations of the eagles, the following targets must be obtained, in order of importance: to reduce the adult mortality, to increase the pre-adult survival and to support a moderate-high productivity.

Another fundamental aspect consists of guaranteeing the conservation of their territories by means of the maintenance of suitable habitats and of viable populations of their optimal preys.

For this reason there have been realized specific studies of diagnosis of the principal problems that concern the eagles. The Team also participate in the application of these conservation measures. Principal courses of action:

Reduction of the mortality

Study and correction of the impact of the electrocution in power lines


Suport de derivació molt perillós. (Foto: Joan Real)

The electrocution is the cause of 60 % of the deaths of Bonelli's Eagles in Catalonia (adults and non-adults). For this reason studies have been realized to detect the principal points of electrocution in breeding and dispersal areas of Bonelli's Eagle in Catalonia.  

Studies in the nesting areas of Bonelli´s Eagle

More than 20,000 electrical supports located in the sectors precoastal and coastal of the province of Barcelona are cartografhied; they are included in the natural parks of Sant Llorenç of the Munt - Serra de l'Obac, Montseny and Garraf, in the Spaces of  Natural Interest (EIN) of Cingles de Bertí, Gallifa, l'Ordal and in the areas located around all these protected natural spaces.

It is determined that the correction of all the supports catalogued like more dangerous, approximately a 5% of the total, would avoid 70% of the electrocutions of birds that take place in this zone.

Study financed by the Area of Natural Spaces of the Diputació de Barcelona.


Studies in the dispersal areas of juveniles of Bonelli's Eagle

Collaboration in a study to detect the principal points of electrocution existing in the dispersal areas of  the juveniles of Bonelli's Eagle placed in the province of Lerida (IBA 142 and 144).

It is determined the electrocution risk of more than 3,000 pylons placed in a total area of 800 km2.

It is stated that these natural areas of the province of Lerida are one of the principal zones of Catalonia where the electrocution affects more seriously a great number of birds, principally juveniles of several species of birds of prey.

Work financed by the Servei de Protecció de la Natura of the Departament de Medi Ambient of the Generalitat de Catalunya and the Fundació Miquel Torres.


Application of anti-electrocution measures

1. Signature of a pioneering agreement of collaboration in Catalonia involving the company FECSA-ENDESA, the Diputació de Barcelona and the Universitat de Barcelona, for the detection and later correction of the electric pylons that bear a major risk of electrocution for the birds present in the province of Barcelona.  

The Departament de Biologia Animal of the Universitat de Barcelona advises the technicians of FECSA-ENDESA in the tasks of correction of the dangerous electricity pylons, and develops the new studies for the location of power lines dangerous for the birds. The company FECSA-ENDESA realizes the corrections agreed with the researchers of the University of Barcelona, and assumes the economic expenses derived from the application of these measures. The Àrea d'Espais Naturals of the Diputació de Barcelona watches over the correct application of the work plan and finances new studies for the location of electrocution points  for birds within the territorial limits of the open spaces that it manages.

In the framework of this agreement there have been corrected 450 dangerous pylons placed in the Nature Reserve of Sant Llorenç del Munt – l´Obac and outskirts (province of Barcelona), in an area where three adult specimen of Bonelli´s Eagle had been found electrocuted. In the later monitorings of the corrected supports any bird species has been found electrocuted.

2. Signature of an agreement of collaboration with the company ELECTRA CALDENSE S.A. from Caldes de Montbui (province of Barcelona) and the Diputació de Barcelona, to locate and to correct the dangerous pylons present in the power lines of distribution of its property, which are included in  two territories of Bonelli's Eagle.  

3. Signature of an agreement of collaboration with the company ESTABANELL Y PAHISA ENERGIA SA of Granollers (province of Barcelona) and the Diputació de Barcelona, to locate and to correct the present dangerous pylons in the power lines of distribution of its property in a territory of Bonelli's eagle.

Bibliographical references : A28, C21, E12, E13, E14, E15 and E17.

See also the news section.

Study and correction of the collision in power lines

Línia de transport (Foto: Albert Tintó)

The collision with power lines is the cause of a 10% of the deaths of adult Bonelli’s eagles in Catalunya. In order to solve this problem studies have been carried out to determine the interaction of the eagles with the power lines of transport (high tension) and which can be the points with a greater collision danger. Also the application of correcting measures has begun.

Study of the risk of collision of all the transport power lines present in territories of Bonelli's Eagle in Catalonia

Cartography of the transport power lines present in all the territories of Bonelli's Eagle in Catalonia (960 km), and determination of the stretches that imply more risk of collision for the eagles.

 Works financed by the company Red Eléctrica de España.

See also the news section.

Espiral anticol·lisió (Foto: Albert Tintó)

Application of anti-collision measures in transport power lines of the province of Tarragona

Signaling with spirals anticollision of sections where it is known that Bonelli’s eagles have died by collision. Sections between Mas de Riudoms and Vandellós (province of Tarragona) and surroundings of the Park of the Garraf (province of Barcelona).

Actions realized with the collaboration of the company Red Eléctrica de España.

Línia fora de servei a la que se li han retirat els cables (Foto: Albert Tintó)

Application of anti-collision measures in the Nature reserve of Sant Llorenç del Munt and l'Obac

Withdrawn of an static wire of a transport power line out of order that crosses the Nature Reserve of Sant Llorenç del  Munt - Serra de l'Obac (Barcelona) and that meant a serious risk of collision for a pair of Bonelli´s eagles that breeds and hunts in this area.

Work realized with the collaboration of FECSA-ENDESA and the Diputació de Barcelona.

Bibliographical references : A26 and A16.

(Foto: Albert Tintó)

Detection of the areas where the birds of prey are persecuted

Thanks to the information obtained in the annual monitoring and studies there have been detected areas where the eagles are still persecuted. The realized tasks consisted of informing the competent authorities and collaborating with them to try to solve the problem.

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Improvement of the reproductive success

Vigilance of nests

In several occasions it has been observed that certain breeding areas were being affected by activities that cause inconveniences next to the nests (hiking, climbing and other practices of free time). For this reason have been realized works of specific vigilance of pairs threatened by activities that could cause the reproduction failure or even the definitive abandonment of the territory.

These performances have been realized in close collaboration with naturalists, owners of the areas, administrations and principal involved groups.

Supplementary feeding

In territories where every year the eagles didn’t the reproduction successfully for lack of food, a supplementary contribution of preys was done. This action helped females to obtain a physical state suitable to realize the laying and guarantee the feeding of the chicks. Also autonomous dovecots were established and several repopulations were realized in territories especially poor in preys.

This measure could be carried out thanks to the voluntary collaboration of many naturalists and private owners, which contributed decisively to achieving the successful breeding of the pairs.

Bibliographical references: C4.

Reduction of the hunting pressure

Provided that the food absence is associated in enough occasions with an inadequate hunting management, actions have been taken to solve this problem.

  1. Request and advice for the creation of prey species preserves, Security Areas and controlled game preserves in nesting and hunting areas for the eagles present in public or private properties.
  2. Agreements with owners to reduce the hunting pressure or to suppress completely this activity in their properties.
  3. Censuses and plans of hunting arrangement in areas of St. Llorenç del Munt, Garraf, Puigventós and Cingles de Bertí. Collaboration with societies of hunters in the writing of hunting plans and the application of measures to improve the populations of hunting species.

Regulation of the free time activities 

Certain activities of the free time bear inconveniences in the nesting areas that can cause a failure in the breeding and even the abandonment of these areas. For this reason some works have been realized to regulate the climbing in the nature reserve of the Garraf and of Sant Llorenç del Munt. This has provoked that in these areas the eagles reproduce successfully again. It has also affected the regulation of some activities of free time such as those related to mountain bikes, air devices and hiking, trying to offer alternative itineraries that do not bear inconveniences for the eagles.

Bibliographical references : C8.

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Limitació del pas a vehicles no autoritzats (Foto: Albert Tintó)

Conservation of the habitats 

The conservation of the habitats of Bonelli's Eagle is principally a responsibility of the administrations and of the private owners. For this reason the realized actions have been carried out in collaboration with public organizations and particular owners.

Analysis and mitigation of environmental impacts

  • Regulation of the tracing of road infrastructures and the use of forest trails and tracks.
  • Achievement of works where the best tracings for road infrastructures are recommended in order to affect as little as possible the territories and the activities of Bonelli's Eagle pairs.
  • Collaboration with the administrations and private owners to recommend a rational use of forest trails and tracks close to nests of Bonelli's Eagles.

Achievement of management plans

Writing of plans of integral management of the human activities inopen areas where there are territories of Bonelli's Eagle

These plans include the recovery of the agricultural and cattle activities, the regulation of the forest activities, the hunting, the free time activities and the traffic of vehicles along the forest trails. There have been also proposed specific measures for an active and sustainable management of the habitat and activities of information to the population and interested groups.

These works have been carried out till now in the E.I.N. of Cingles de Bertí (Vallès Oriental), Sant Salvador de les Espases (Vallès Occidental and Baix Llobregat), and in the farms near to the Nature Reserve of Sant Llorenç del Munt and l'Obac (Vallès Occidental).

See also the news section.

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(Foto: Albert Tintó)

Technical-administrative mesures

Achievement of technical reports of planning or management directed to autonomic, state and European administrations, or NGOs, so that they serve for the conservation of Bonelli's Eagle.
  • Request and later approval for Birdlife International of a “Important Bird Area " in the pre-littoral Sierra of the regions of Barcelona, one of the most northern areas of distribution of the Iberian population of Bonelli's Eagle.
  • Inform to the Headquarter of Environment of the European Union about the mountainous pre-littoral sierras of the province of Barcelona as an IBA (Important Bird Area) key for the conservation of Bonelli's Eagle.
  • Report on the situation of Bonelli's Eagle in Catalonia for the MIMAM (Ministerio de Medio Ambiente).
  • Participation in the writing of the European Plan of Action of Bonelli's Eagle. Birdlife International and European Union.
  • Writing and coordination of the Strategy for the conservation of Bonelli's Eagle in Spain for the MIMAM.
  • Writing of a document of Proposal of mitigation of the electrocution of Bonelli's Eagle in Catalonia for the MIMAM.
  • Writing and coordination of the text of Bonelli's Eagle for the Red Book of the Vertebrates of Spain (SEO-MIMAM).

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(Foto: Francesc Tintó)

Studies to detect the principal points of electrocution

The studies are carried out by means of the following plan of work:

  1. To cartography the distribution power lines present in the study area.
  2. To characterize all the electricity pylons. To determine its principal electro technical parameters, the characteristics of the surrounding habitat and the presence of species that can be affected by the electrocution.
  3. To analyze the characterized pylons and to select the principal focus of electrocution of birds, by means of the application of a statistical model that determines the risk of electrocution of every pylon from his electro technical characteristics, of the surrounding habitat and of the presence of threatened species in the areas where they are located.
  4. To catalogue and cartography all the electric pylons. To locate accurately the principal black points.
  5. To propose measures of correction adapted for each of the dangerous located pylons.

The obtained results indicate that the pylons that cause the majority of the electrocutions are a very limited percentage (between 3 and 5 % of the whole). These supports are principally metallic and they are placed in open areas with plenty of prey species.

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