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No end to the electrocution of Bonelli’s Eagles: this time it happened to 'Álora'

As in previous occasions (sadly too many), we regret to inform you about the loss of another animal we had been monitori...

First egg of a Bonelli’s Eagle in 2016

Our captivity breeding team observed attentively the cameras, but finally the female Bonelli’s Eagle chose to lay her fi...

At your disposition the Virtual Library of the Bonelli’s Eagle

In the Virtual Library of the Bonelli’s Eagle we offer you around 300 documents related to the Bonelli’s Eagle, its cons...

Life Bonelli: Improvement measures of habitat in Navarra

As part of the Life Bonelli Project, several improvement measures of the habitat of Bonelli’s Eagles are planned. During...



- Action A.1 -



1. INTRODUCTION - Selection process of the Sites:

The Project suggests concentrating efforts on habitat improvement and hacking in one or two territories that have been recently abandoned by the Bonelli Eagle in Alava, maintaining that effort in each territory during, at least 3-4 years, which is the minimum period necessary to check the philopatric return of the chickens that were liberated.  The settlement would be changed just in the case of recovering the territory, or unexpected difficulties. Otherwise, the effort for setting free would be maintained until re-colonization is achieved and so forth until the end of the project.

There has been a selection of the most appropriate areas for the first hacking experience of 2015, assessing the pros and cons of the different settlements considered, corresponding to the old territories that were abandoned, in order to make an exhaustive evaluation during 2014 and choose the definitive and most adequate place to develop successfully the first step (the hacking of the chickens breed in captivity) but most of all, to reach the target of the project which is the recovery of the Bonelli eagle’s territory in our Historic Territory.

We selected 6 suitable settlements on the first place for reinforcing of the population of Bonelli eagles in Alava.  These settlements are historic territories of Bonelli eagles in Navarra, which have been occupied until relatively recent times. In all of them, we have detected either territorialized specimens during the last two decades or wanderer specimens or breeding couples or that, at least, could be able to guarantee a successful re-introduction.

Each of these settlements has been assessed taking into account the previous presence as a breeding specie, the approximate date when they left the territory, repetitive observation of specimens in their process of re-colonization, the absence of risk of accidents and/or predation, the lack of human trouble around the area or the possibility of diminishing it, the conservation of the Mediterranean demi-forest habitat, a favourable topography for the protection of the fledglings as well as the level of regional and/or European of protection.

For the final process of selection there will be an examination of the abundance of potential preys, the awareness and disposition of the local entities towards the initiation of the program and the willingness to cooperate of the hunting grounds.


ZEPA  Valderejo- Sierra de Árcena  ES0000245

Area: 6 676 000 ha
Coincidence with LIC ES2110001 Valderejo and ES2110002 Sobrón.


ZEPA Sierras Meridionales de Álava ES0000246

Area: 16 410 000 ha
Coincidence with LIC ES2110018 Sierra Cantabria and  ES2110020 Río Ega-Berrón.



Coincidence with LIC ES2110019 with the same name.

Area: 9 000 ha

Public (UP hills) 8644 ha.
Private: 361 ha.



Action A.1 LIFE BONELLI (LIFE12 NAT/ES/000701)


In 2010, as part of the preparatory phase of the Re-introduction Plan of Bonelli Eagle in Mallorca, there was an assessment of various sites, in order to proceed to liberations from 2011 onwards.

The selection criteria used for this analysis seemed the adequate, considering the success of the experimental liberations in 2011, 2012 and 2013.



We have assessed the suitability of 30 sites in the Sierra de Tramuntana and Sierra de Levante, based on the list of public estate (owned by the State, the Balearic Island Government, the Consell Insular de Mallorca and town councils) also adding private estate considered advantageous. The methodology is based in two phases.

PHASE 1. SCORING OF 11 ITEMS. Various estates assessed have been assessed which almost matched the necessary conditions for liberating chickens by hacking or fledglings by acclimation cage, scoring them from 1 to 0 (most suitable to less suitable) regarding the following 11 items:

  1. Tranquility: considering the intense public use and the access easiness for visitors or tourists with vehicles, bicycles, walking etc.
    • 1: high tranquility.
    • 0,5: a certain level of public use that may require de application of control
    • 0: intense public use, difficult to control
  2. Suitability for the hacking method: a natural corner attached to a shelf, with access from the upper part in order to provide food through a tube without being spotted by the eagles, good visibility where a scaffold with the nest on the top can be installed, the access must be 5-10 minutes max, walking from the vehicle, possibility to watch the evolution of the birds from a prudential distance.
    • 1: Suitable site for hacking liberation
    • 0,5: Hacking liberation is feasible, although not suitable in advance
    • 0: the settlement is not suitable for liberation via hacking
  3. Suitability to install and liberate via acclimation cage: flat area that can be reached with a truck to install a cage 10-15 meters long by 3-4 wide that can be discrete between the trees but with front visibility at least and the possibility to access from the back side in order to provide with food and also the possibility to survey from a relatively close distance, enough to watch the specimens’ behaviour.
    • 1. Suitable site for liberation via acclimation cage
    • 0,5: It could be feasible to liberate via cage although it doesn’t seem suitable
    • 0: the site is not suitable for liberating via acclimation cage
  4. Current presence of the specie: Recent record of the Bonelli Eagle in the area.
    • 1: settlement area of liberated birds
    • 0,5: area within kernel 90 zone
    • 0: non-visited area and not within kernel 90
  5. Historic data on reproduction: Based on the distance from old known territories.
    • 1: Old known territory, less than 5 km apart
    • 0,5: Old known territory less than 15 km apart
    • 0: Old known territory more than 15 km apart
  6. Potential preys: Varied and abundant diet.
    • 1: Varied and sufficient diet
    • 0,5: Not varied but sufficient
    • 0: neither varied nor sufficient
  7. Zepa: Within any of the sites Natura 2000 of Life Bonelli.
    • 1: Life Bonelli ZEPA
    • 0,5: ZEPA not in Life Bonelli or LIC
    • 0: Not ZEPA
  8. Good disposition towards the project of property owners and local entities
    • 1: Good disposition
    • 0,5: not a good disposition but it could be improved
    • 0: no disposition and it is difficult to improve it
  9. Risk of negative interaction with protected species: Depending on the presence of territories for reproduction, troughs, sleeping places, etc. of other threatened species with which the Bonelli eagle could interact negatively; including a couple of a territorial Bonelli eagle.
    • 1. No risk
    • 0,5: no major risk
    • 0: major risk
  10. Presence of threatening elements: such us overhead wire, ponds that could involve drowning, intensive hunting, etc. less than 2km apart.
    • 1. No risky elements in 2 km around
    • 0,5 there are some risky elements that could be corrected easily
    • 0: there are risky elements that are not easy to correct.
  11. Habitat suitability: presence of a suitable habitat, in a good state of preservation and with no risk of usage modification that could compromise the project.  Based on a suitability analysis of the habitat performed by the Malaga University in 2011 in UTM 1x1 as part of the previous works accomplished before the experimental liberation phase in Mallorca.
    • 1. Suitable habitat, in a good state of preservation
    • 0,5 adequate habitat but not suitable; in a good state of preservation and no risk of usage changes (yellow in the grid)
    • 0: Non-suitable habitat or with a high risk of usage changes that could compromise the project.

Regardless the final score, the following evaluated sites have been dismissed:

  • Places with zero score in items 2 and 3 at the same time (due to the fact that they are not adequate for any liberation method a priori.
  • Outside LIFE Bonelli Natura 2000 (0 or 0,5 in item 7)
  • Place with zero score on item 9, due to the high risk of affecting protected species
  • High mortality risk areas (zero score in item 10)



The study confirms that in 2014 the chickens that were liberated via hacking in Mallorca may continue in xxx, where the installations are mounted, the system is ready and there is no territorial couple up to date.

The acclimation cage for the liberation of birds capable of flying will be installed in a public estate in March 2014.

For the next years, as forecasted by the LIFE BONELLI project, these locations will be reviewed in order to confirm if a couple has established nearby.



Action A.1. LIFE BONELLI (LIFE12/NAT/ES/000701)
15 March /2014


  Facing the possibility of liberating Bonelli eagles in the Comunidad de Madrid during 2008 and 2009, Viability studies (FICAS) were developed, advancing the pilot liberation on 2010-2013. The present study gathers the information of such actions with the necessary updating to be studied.

    In the light of the pilot liberations’ results (xxxx) we could say that the place of liberation is the right one since the majority of specimens that were liberated during the pilot phase, overcame the dependency period.

Una de las últimas águilas de bonelli de MadridThe Comunidad de Madrid counts on two breeding couples in its territory and another two couples shared with Comunidad de Castilla-La Mancha.  None of the the first ones got their chicks off the groung, but the couples shared by both Comunidades, did.

It is very interesting the fact that various specimens meet at the perimeter of the liberation area (they were seen 3 times in March 2014) a young couple seen in Velilla de San Antonio municipal area (seen twice, February and March 2014) one adult specimen in Tielmes municipal area (March 2014).  Therefore, there is another specimen (marked with a GPS) coming from Castilla-La Mancha who is now established in the Chinchon area.  No breeding activity has been observed (this information has been provided be LIFE PrioriMancha)



Although there is no agreement on the number of couples that once lived in the Comunidad de Madrid, different authors seem to coincide that the Bonelli Eagle was never common, though they highlight the existence of areas where there may have lived in  higher numbers (Arroyo 1991):

  • South-East of the Comunidad de Madrid.
  • South-West of the Comunidad de Madrid.

The presence of 16 couples Bonelli eagles was established on these works. It is considered a small population for 1970 decade set up by 9 (Arroyo 1995) or 10 couples (Del Moral 2006).

To establish the size of the population as well as the areas where they existed, is a key information to determine the potential area for the Bonelli Eagle in the Comunidad de Madrid. Nevertheless, the existing information based on the census job previously mentioned, is scarce, especially when trying to establish the history of each couple and/or placing the specific sites for nestling.



Four core sites were considered: The North Mountains, the Guadarrama Mountains and its ramp, the South-east and south-west mountains. The higher number have been watched within the last two. It is for this reason and others already explained that we shall develop a detailed study of these two areas:

  •  01 ZEC Basin of the rivers Alberche and Cofio ES3110007
  •  07 ZEPA Canyon walls and cliffs of the rivers Manzanares and Jarama ES0000142


01 ZEC Cuencas de los ríos Alberche y Cofio ES3110007 07 ZEPA Cortados y cantiles de los ríos Manzanares y Jarama  ES0000142


Initially we could say:

  • South-west Mountains (ZEC Basins of the rivers Alberche and Cofio, 1): This is an area where adults and immature specimens are regularly watched.  There’s a high competition with other eagles, but these mountains are placed next to dispersion areas.
  • South-east (ZEPA Canyon walls and cliffs of the rivers Manzanares and Jarama), 2): This is the area where most of the wanderer individuals are watched, most probably because of the high availability of trophic resources.



Hence, in the South-west area (Zepa of the holm-oak woods of the rivers Alberche and Cofio), the most suitable place to install the “hacking” is the section known as xxxx. It is the same place where the pilot experience was established.
Should a potential occupation of the South-West area occurred, the next site would be the Estate xxx (Zepa canyon walls and cliffs of the rivers Jarama and Manzanares)



Arroyo, B. y Garza, V. 1991. Reporto n the situation of the Bonelli Eagle in the Comunidad de Madrid. Unpublished report for the Environment Agency of the Comunidad de Madrid.
Arroyo, B., Ferreiro, E. y Garza,V. 1995. Bonelli Eagle (Hieraaetus fasciatus) in Spain. Census, reproduction and preservation. Colección Técnica. ICONA. Ministerio de Agricultura, Pesca y Alimentación. Madrid.
Del Moral, J. C. (Ed.) 2006. The Bonelli Eagle in Spain. Population in 2005 and census methodology. SEO/BirdLife. Madrid.

FICAS. 2008. Research on viability in the SW of Comunidad de Madrid for the re-introduction of the Bonelli Eagle  (Hieraaetus fasciatus). Majadahonda. Madrid.

FICAS. 2009. Viability analysis for the re-introduction of the Bonelli Eagle (Hieraaetus fasciatus) In the SE of Comunidad de Madrid.  Selection of settlements for the re-introduction. Majadahonda. Madrid.




Action A.1



 1.Extract from Fernandez and Azkona, P.2012. Improvement of the habitat and reinforcement of the Bonelli eagles’ population (Aquila Fasciata) in Navarra. Biodiversity Conservation Service. Government of Navarra.


Site selection:

    The Project plans the concentration of efforts for the habitat’s improvement and hacking in one or two territories which the Bonelli eagle has recently abandoned (Fernandez and Azkona 2010), maintaining such effort in each territory for at least 3-4 years; minimum period necessary in order to confirm the philopatric return of the chickens that were liberated. The site would be changed only in case that the territory was recovered or unexpected difficulties.  Otherwise, the liberation effort would be maintained until the re-colonization of the territory and so forth until the end of the project.

    This is the reason why there has been a very detailed selection of the most suitable site for the first hacking experience, assessing the pros and cons of the different sites considered and finally selecting the most suitable one to develop successfully the first step (the hacking of the chickens breed in captivity) but, most of all, in order to reach the final goal of the project which is the recovery of the territories of the Bonelli eagle in our Community.

    Initially, eight suitable sites were selected which were adequate for the reinforcement of the Bonelli eagle population in Navarra.  Five of these are historic territories of the Bonelli eagle in Navarra, and have been occupied until recently and in the other 3, either wanderer specimens have been detected or there could be some breeding couple “a priori” or that at least, they could guarantee a successful re-introduction.

   Each of these sites was assessed separately taking into account: 1st. The previous presence of the breeding specie; 2nd. Approximate date when the site was abandoned, 3rd. Specimens have been detected repeatedly in their process of re-colonization. 4th. Abundance of potential preys. 5th. lack of risk of accidents and/or predation. 6th. Lack of human trouble in the area and the feasibility of diminishing them. 7th. Good preservation of the Mediterranean demi-forest habitat. 8th. Favourable topography for the fledglings. 9th.  The level of protection both regional and European. And 10th. Awareness and disposition of the local entities towards the program.
The final choice was made on the basis of the historic presence of the Bonelli Eagle in the territory, the previous efforts made on habitat improvement regarding the buffering of electrocution risks and collision with the overhead wiring, the distance from wind farms and nestling areas of predator and competence species, the recovery ability of the potential preys and a real possibility of re-colonization based on the philopatric return favoured by the Program.

Xxxx, xxxx, xxx, xxxx y, en menor medida, xxxx tenían a favor la existencia de un espacio natural protegido, con un plan de gestión en vigor y su declaración como Zona de Especial Protección para la Aves dentro de la Red Natura 2000 (Directiva Aves 79/409/CE). Xxxx y xxxx contaban a su favor con la reproducción de la especie hasta épocas muy recientes y en su contra la intensa utilización de los mejores cortados para la práctica de la escalada; por lo que, como paso previo, habrían precisado una importante regulación de la actividad deportiva y restricciones de uso en los cortados.

Xxxx, xxxx, xxx, xxxx and, to a lesser extent xxxx, had the advantage of the existing protected natural area with a managing plan in force and declared as Special Protection Area for Birds within the Red Natura 2000 (Bird Directive 79/409/CE).  Xxxx, and xxxx had on their side that the specie had bred until recently and against it the intensive use of the best cliffs for climbing; hence a heavy regulation of this activity as well as restrictive use of the cliffs would have been necessary.

Xxxx and xxxx were discarded almost immediately due to the wind farms nearby, less than 3 km from the cliffs that were ideal for hacking.  On the other hand and thanks to the effort made for the processing and restructuring on the last decades (Fernández y Azkona 2004) none of the possible sites were excluded because of the overhead wiring posing electrocution and/or collision threat ; although this factor was considered as a negative element in the Falces case.

It was also a great handicap for xxx, xxxx, xxxx that big prey birds such as the Eagle Owl (bubo bubo) or the Golden eagle (Aquila chrysaëtos) nestled less than 1 km from the valid sites for hacking. They could compete or even prey on the chicken of the Bonelli eagle (Fernández and Insausti 1991).

At first, xxxx, seems to have excellent ecological conditions for the Bonnelli Eagle to occupy, nevertheless it was dismissed for two main reasons: 1st. In spite of its appearance, this is not an old territory and there is no record of specimens of the sporadic population of Bonelli eagles, which may indicate the existence of some kind of environmental factor escaping from our reach; 2nd. Its accessibility and visibility is limited which may have hindered the field work.  In spite of this, this is, along with xxxx and xxx, an alternative in the case that for practical reasons or because of the recolonization of xxx, it would be necessary to continue the program in some other settlement.  The qualities that have been specially well rated in xxx are: 1st. it is one of the last territories of our Community that has been abandoned, and there is and sporadic presence of adult and immature specimens until 2010 (Fernandez y Azkona 2010), 2nd. Its bio-geographic position , in an area relatively far from other territories of the Bonelli eagle in the Valle del Ebro, and 3rd. the excellent disposition and collaboration of the Council and the local population in the launching and the development of the Program.

One of the few points against xxx was its relatively lack of food (rabbit and partridge) which we thought it could be solved in the short term, providing food periodically and in the midterm, developing actions to improve the habitat; but during the hacking process we confirmed that this shortage is compensated with columbidae which nestle in the pine woods around San Pedro (woodpidgeon) and in the groves of the river Aragón (common woodpidgeon).




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