Interview with Marc Lecacheur about the biology and conservation of the Bonelli's Eagle in France

Date of the interview: 28 October 2009

The Bonelli's Eagle is one of the most endangered raptors in Europe. In this interview, Marc Lecacheur talks about the current situation of this species in France.

Markus Jais: What is the current status of the Bonelli's Eagle in France in 2009 (number of breeding pairs, numbers of young fledged)?
Marc Lecacheur: There are 29 breeding pairs in France which gave 28 flying juveniles at the end of the breeding season. 25 juveniles were ringed this year.

Bonelli's Eagle

Adult Bonelli's Eagle, Spain, May 2009, © Markus Jais

Markus Jais: In what areas in France do Bonelli's Eagles nest? What habitat do they occupy?
Marc Lecacheur: They typically nest in areas under mediterranean influence, usually under 1000 meters above sea level.They occupy gorges, or mattoral areas where undisturbed cliffs are available.

Markus Jais: Do all pairs nest on cliffs or are trees used, too?
Marc Lecacheur: They mainly nest on cliffs. Only one pair nests on a pylon in the PACA region.

Markus Jais: Is there an exchange with breeding populations in Spain or other countries like Italy? Are the dispersal areas for juvenile birds known?
Marc Lecacheur: There is an exchange with the Spanish population, apparently none with the Italian one. But many juvenils disperse in France. Once they become autonomous, the young birds tend to concentrate in specific areas, where prey are readily available and where there is no competition with adult birds. Three areas have been identified in France for this matter.

Markus Jais: What is the main food for Bonelli's Eagles in France? Is there enough food, for example, rabbits?
Marc Lecacheur: Rabbits and partridges are commonly identified as the main prey but in reality, the species is very opportunistic and preys on other animals depending on the resources of its habitats. For instance, along the seashores , some pairs have become gull's hunters. Near rivers and gorges, other pairs often catches birds such as the Grey heron (Ardea cinerea). Squirrels, pigeons, which live in forested habitats are also preyed on. It proves that Aquila fasciata is able to adapt to the modifications of the mediterranean vegetation. Until now, food resources do not seem to be a limiting factior. The big problem is the mortality of the adults.

Markus Jais: What are the main threats to Bonelli's Eagles in France?
Marc Lecacheur: Electrocution and collision on power lines, poaching, disturbances on its breeding sites, modifications of its habitats, some diseases such as trichomonosis.

Markus Jais: In Spain, electrocution is among the most serious threats to the Bonelli's Eagle. How is the situation in France?
Marc Lecacheur: It is quite the same in France. Some 47% of mortality cases happen to be due to electrocution. Unfortunately, we still struggle to involve electricity companies to solve this problem. Since 1990, at least 24 birds have been found electrocuted on powerlines. This data is a minimum, considering the difficulty to find the carcasses, but for a population hardly reaching 30 pairs, one can easily understand the impact on the population dynamic...
Poaching is an important cause of mortality too, but hard to evaluate. Very often, the birds found electrocuted have bullets in their body. It proves, there are still people who shoot birds of prey, probably because of ignorance or prejudices.

Markus Jais: Is there competition between Bonelli's Eagles and other species like Golden Eagles or Eagle Owls?
Marc Lecacheur: Yes, several sites "left" by the Bonelli's Eagle are now occupied by the Golden Eagle. In fact, the population dynamics of the two species are totally different in France. The Golden Eagle population is increasing rapidly, whereas Bonelli's Eagles hardly stabilize their numbers.
In 2009, for instance, in the PACA region, one pair of Bonelli's Eagles has simply been delocated by a pair of Golden Eagles who now occupy the cliff. The two Bonelli's Eagles have built another nest 5 kilometers away from there, but haven't been able to breed this year, probably because they didn't know this new area well.

Predation of eagle owls has been proved on young Bonelli's eagle, so for sure, this can be a limiting factor too.

Markus Jais: There is a national plan for the Bonelli's Eagle in France. What is the goal of the plan and how can it be achieved?
Marc Lecacheur: The goal of this Plan is simple: to stablize and to increase the numbers of Bonelli's eagles in France, by reducing the threats weighing on the species.

The first step is to know the population the best we can, by monitoring every pair during the breeding season, but also to check all the "empty" sites to be sure we don't miss any pair reestablishing itself.

Then, the reduction of the threats means:

  • for electrocution: negociations with electricity companies to ensure dangerous lines are equipped to minimize the risk. Our network provides maps of dangerous lines but budget for equipment is too low to really change something
  • for poaching: enforcement of the law in the sensitive areas, partnerships with hunter's associations...
  • disturbance: local partnership with several users of the land such as climbers, hikers, paragliders...
  • habitats: actions to improve the attractivity of the territory (burning, wood clearings...)

Markus Jais: Who is involved in the conservation work for the Bonelli's Eagle in France?
Marc Lecacheur: The Conservatoire des Espaces Naturels du Languedoc-Roussillon (CENLR), based in Montpellier, is in charge of the coordination of the Plan under the direction of the French Ministry of Environnement. Other NGOs such as the CEEP and the CORA FS coordinate the actions at a regional level. Many local NGOs are involved in the partnership too(GOR, COGard, LPO Aude, LPO Hérault, La Salsepareille). On the field, some 60 people ensure the monitoring of the pairs. Many of them are volunteers, others work for collectivities, NGOs. Check out our website to know more:

Markus Jais: How do you see the future of the Bonelli's Eagle in France?
Marc Lecacheur: I think it will depend on the effective involvement of electricity companies who need to realize how important it is to solve the problem of electrocution. If the mortality rate of adult birds dicreases, then the dynamic will be reversed.
It will depend as well on the scientific and naturalist "network", its capacity to federate itself, to defend the same tasks.

Mentalities need to evolve as well, because it is incredible to see that birds are still shot nowadays. We need to communicate more, to make people understand that big birds such as the Bonelli's eagle are a fundamental element of our biodiversity, an indicator of the health of our mediterranean habitats.

Please note we organize an international symposium on the 28th/29th of January 2010 in Montpellier (France), to present the actions led during the past five years and to elaborate the future conservation strategy for the species. People from France, Spain, Portugal and beyond will share their experience. If some of you are interested to be involved, please contact me by email or on the phone: 0033 467 29 90 65,

Markus Jais: Marc, thank you very much for the interview!

Further Information