An unusual bird

Presentation :

The white-tailed sea eagle is one of the largest diurnal raptors in Europe. The total length of the adult bird is 70-100 cm, with a wingspan of 190-250 cm. Its weight varies from about 4 kg for the male to 6 kg for the female. The plumage of the adults is brown except the head and neck which are lighter. The wings are long and rectangular, their tips reach the tip of the tail. The head is large, the neck is powerful, and the strong beak is entirely yellow. The short and fan-shaped tail-shaped tail is entirely white. The legs are yellow. Apart from this difference in size and weight, sexual dimorphism is not very marked (Ferguson-Lees, Christie, Franklin, Mead, & Burton, 2001). A complete molt takes place over several years, mainly between April and October.

Fish-catching eagles have two-thirds bare tarsi, plantar soles covered with rigid spicules, rather short toes, and highly arched talons that allow them to capture and hold large fish (Orabi P, 2012). Juveniles are darker, especially at the head, and have a variably light spotted mantle. The tail is largely dark, the bill is black, and the iris is quite dark. In subadults, the tail has a dark terminal band, before turning white. Five to six plumages can be distinguished in this species. Age determination is possible up to and including the 4th plumage, knowing that there are individual variations in plumage between two birds of the same age which can lead to an erroneous age estimation ( LOANA (Lorraine Association Nature) published in 2016 a guide to help identify the different plumages of the White-tailed sea eagle as part of the Regional Action Plan 2015-2020 on sea eagles in Lorraine ).

Adult male white-tailed eagle. Photo credit Les Aigles du Léman


The National Action Plan for the eagle states:

It is from the age of 5 or 6 years that the eagle begins to reproduce but observations of subadult reproduction have already been made for pairs formed before the average age of sexual maturity of individuals. White-tailed sea eagles prefer to nest on tall trees (deciduous trees usually over 10 m high or conifers), usually in the upper third of the tree, but may also build their nests on steep rock faces, more rarely on the ground. The nest is made of large dead branches, lined with mosses, lichens, dry grass, …Nesting areas are rare on infrastructure such as electricity pylons or towers.

Eagles refill their nests each year in late winter, with the male providing most of the materials while the female arranges the nest. Fresh plant material continues throughout the breeding season. The eagle may have several sites on its breeding territory. Egg laying takes place from late January to late April, depending on latitude and climate. The female lays 1 to 3 eggs, usually 2, incubated in turn by the two adults for
about 35 to 38 days. At hatching, the chicks weigh 80-95 g to reach 4-6 kg before fledging. The fledging of the young occurs between 2 months and half and 3 months after the hatching. After fledging, they are still fed by the adults for 4 to 5 weeks, then they gradually disperse on the parental territory during the third month. The young reach sexual maturity at about 5 years of age. In healthy populations, reproductive success reaches 60-80% and the number of young fledged is 1.5 (in Germany, between 1991 and 2005) (Sulawa, Robert, Köppen, Hauff & Krone, 2010).

Juvenile White-tailed Eagle. Photo credit Les Aigles du Léman.

The nest.Photo crédit Rémi Chapeaublanc.

Diet of the white-tailed sea eagle:


The white-tailed sea eagle has a rather varied diet, depending on local resources and the season: it feeds mainly on dead or live fish that it catches, as well as captures water birds (ducks, coots, grebes, gulls, etc.) and mammals. It is an opportunist that sometimes feeds on carrion, especially in winter. It does not hesitate to take food from other birds (Osprey, gulls, and cormorants) or from mammals (otters). Eagles forage primarily near the nesting area (4-7 km), but the pair’s range can reach 15-30 km (Patier et al, 2015). Like the Osprey, it takes fish in shallow water after spotting them in flight or from a perch.

According to a study conducted in Germany on 5 pairs of eagles, they prefer to catch bream and pike and avoid perch, roach, and eel. In general, the size of the prey seems to be decisive: eagles prefer fish of 30-50 cm, those larger than 50 cm are not consumed (Nadjafzadeh et al, 2015). Work has shown that adult white-tailed sea eagles require 500 g of fish or 300 g of bird or mammal flesh daily; the daily requirements of juveniles are about 800 g, mostly of fish (Orabi, 2012).

History in France:

From popular expression to hated animal

The French ornithological literature finally makes little room for the white-tailed sea eagle.There are no engravings attesting to the presence of eagles but a popular expression: “Pousser des cris d’Orfraie” This expression comes from the extremely high-pitched cries that these birds utter at
the time of the reproduction period. Eagle was the name of the white-tailed sea eagle in the Middle Ages. Few animals have given popular expressions : the wolf, the bear and thus the white-tailed sea eagle. This indicates that it was necessarily very present in the country. This is confirmed by authors who claim that eagles were nesting everywhere in France in the 18th century. Then the persecutions made its population decline in a dramatic way. Flourens mentions a nesting in the forest of Chambord in 1780 then Victor Fatio describes very precisely the last nesting in continental France in the forest of Ripaille in Thonon les Bains (Haute-Savoie) in 1892 In Corsica, the bird nested until the late 1950s, early 1960s.

  •  2011: The natural return

In 2011 a couple comes to settle naturally in Lorraine and raises successively nestlings. It will be necessary to wait until 2018 to see two other couples settle in Brenne and in Champagne.

A 4th pair seems to settle in 2020 between the Marne and the Meuse but without finding the nesting area. The return of the eagles in France shows the extreme fragility of this population and the project of a reintroduction program aiming at reinforcing the latter but also at conquering new territories is quickly imposed as a necessary action for the perennial return of the species in France.

  • 2022-2030: The reintroduction program

From 2022 onwards, the reintroduction program for the white tail sea eagle will take place on the site Les Aigles du Léman, in the commune of Sciez, on the shores of Lake Geneva. 6 birds will first be reintroduced to test all the elements of the program (breeding, method, installation of GPS, surveillance system by cameras…) If all goes well, 80 birds will be released on the Lake Geneva basin. The objective is to recreate a population of 3-4 pairs on the shire of the lake and to start the colonization of the upper Rhône, a region targeted as a priority by the National Action Plan.

Observe and protect

The golden rules:

Whether it is with the aim of observing the eagle or by chance during your activities around the lake, the encounter with the eagle always remains a magical moment. It is most of the time a furtive moment, a flight a few meters above you.

To take full advantage of this moment, here are a few tips to avoid missing anything and to disturb as little as possible this great bird of prey :

  • Do not try to approach or follow it as it can easily become very frightened.
  • Keep away from trees where it is perched because it is resting.
  • Stay calm and do not suddenly make big gestures (to call your friends, take out the camera or your binoculars…).
  • Do not approach a young bird on the ground, it does not need help, it is learning to fly and does not always master its landings! Report its position to the program.
  • Stop and take the time to observe him, if he passes behind a grove of trees or houses, he can return very
  • If you are on the ground and he is in flight, no worries about disturbance, it is the eagle that remains
    master of approaching you or not.
  • If the eagle is eating on a carcass or preening its feathers, be as still as possible because if you are close
    enough, the slightest movement will make it fly away.
  • If you have a pet, do not try to approach, or follow the white tail sea eagle it as it can easily become very frightened.
  • Move away from trees where it is perched as its nest may be very close.
  • Never approach an eagle nest if you know its location, this is the most important disturbance that can lead to the failure of the reproduction and/or the abandonment of the site, which can jeopardize the reintroduction and conservation program !

Regulations prohibit the intentional disturbance of eagles, especially during the breeding and rearing period.
And don’t forget to transmit your observation to the organizations in charge of the follow-up of the species at our e-mail adress

The reintroduction programs

The project :

The idea of a reintroduction program was born in the head of Jacques-Olivier TRAVERS in 2007. At that time the white-tailed sea eagle had disappeared from France since 1959 (Corsica) and 1892 (Thonon les Bains) and the hopes of a quick return seemed very slim.  « Since my childhood, I have a passion for this eagle that I discovered in a book of the Swiss ornithologist Paul Géroudet, I immediately dreamed to see it again in the sky of our country. The road was long because there were very few in captivity and the naturalist community was not very keen to undertake a reintroduction program ».

Success in reproducing the species: In 2007, there were almost no white-tailed eagles in captivity in France and reproduction of the species in zoos was rare. The Park of the eagles of Léman brought the first individuals from Russia in 2009. From 2012 the first couple is formed; it will take four years to reproduce. From 2017 new couples are formed and gradually 2 then 3 couples that reproduce each year. Thanks to the cooperation of French (Puy du Fou, Amnéville) and European (Veldhoven zoo) zoos, 9 pairs, including 5 breeders, will be housed at Les Aigles du Léman in 2021.

To make the species known : To reintroduce a species, it is important that it is perfectly accepted by the public who will be in contact
with it. We have chosen to do a national communication campaign to make the public discover this species. As we don’t have big means at our disposal, we have chosen to make an original campaign based on the production of films and innovative events. During the years 2014 to 2019 we have participated, written, directed, or produced more than a dozen documentaries on white-tailed sea eagles. At the same time our birds have been seen from the Eiffel Tower, the Burj Khalifa, the Olympic Stadium in London, in Vienna, Berlin Rotterdam…The images from the cameras on the backs of our eagles have revealed a unique view of the great glaciers of the Alps, the deserts of the Middle East or the Greek islands…

Creating a consensus: We wanted to make this reintroduction a true regional project and create strong local support. To do this, we consulted all the stakeholders for nearly 2 years: Naturalist association, fisherman, elected officials, scientists, teachers. Through studies, consultations and improvements, the project has gained general approval, which has been reinforced by the discovery of the last reproduction in continental France at Thonon les Bains. This gives all its sense to this project strongly anchored in the preservation of the local heritage.

The parental cleat, our method

For a long time, falconers and naturalists have understood that young birds are able to learn to fly and hunt alone in their first weeks of life. The young birds are taken from nests in the wild or in zoos, brought to the reintroduction area, raised together and then released with food supplementation for a few months. This technique has been proven successful in all reintroduction programs around the world, it’s called hacking.

However, the abrupt separation from the parents and the short time spent on the reintroduction site seem to limit the survival rate of the young. Our idea is to try to improve the survival rate and the fixation on the territory of the young with a new technique that we have named: the parental cleat.

The young are raised directly on the reintroduction site by their parents, in a large aviary, until the age of 8 weeks then they are placed in an external nest but in contact with the parents simply separated by bars. They will thus be able to emancipate themselves at their own pace without any break with the parents. This will not create any trauma linked to the separation with the parents and to the transport to an unknown release site. The studies carried out around this new technique will allow us to know if Jacques-Olivier’s intuition was right or not and if in the future it presents a real evolution for the reintroduction programs.

Scientific research 

The eagle reintroduction project in the Lake Geneva basin will allow many scientists to analyze the data provided by the video surveillance of the birds, the GPS tracking, and the field observations. Publications will regularly report on the progress made by the scientists with whom we collaborate. The work will focus on the following main points :

Validation of the parental cleat technique : The originality of this reintroduction project lies in this new release technique. The objective of the studies that will take place throughout the program (8 years) will try to verify if this new technique brings benefits on the young survival rate and the fixation of the birds on the territory, two crucial points of the reintroduction program. The
phenomenon of recognition of parents will also be studied for a non-colonial species since the eaglets will be able to join their parents as well as other parents because all nests are close. There fore, eaglets can choose the nest where they come back to beg food to adult.


Bird movement : Placing a GPS tag on each reintroduced eagle will allow us to follow bird movement.

Where do they go? How long do they stay in the reintroduction area? Will they join other populations?

These essential questions to understand the possible reconquest of the national territory will be analyzed by one of the best specialists of the question: Bernd Meybug.

The life cycle : The life cycles of birds will also be studied. Modern beacons allow us to know if the birds areactive or not, at what height they fly, how long they spend per day, if they fish or eat carrion…

We will also be able to study the causes of mortality of these eaglets and try to remedy.

Nature’s marvel. ©RemiChapeaublanc.

The reindroduction centers

Our couples 

The project has 5 pairs that have already reproduced. All these couples come from zoological parks (see “our partners”) which participate with us in this reintroduction project. We have made sure that each pair is genetically as close as possible to the source population and that there is no relationship between them. The studies that have been carried out have concluded that from these couples the risk of loss of genetic diversity is almost nonexistent.

Why so many pairs to produce an average of 10 young per year ?

It must be considered that not all pairs reproduce every year and that they do not have 2 or 3 young every year. Then the duration of the program, nearly 10 years, suggests that all the birds will not be able to reach the end of it, mortality, end of reproductive capacity, disease, bad understanding in the couple, it is thus advisable to take precautions to ensure in time the production of young necessary. These numerous couples will also ensure a maximum genetic diversity.

The eagle house

The will of our project is to allow the public to appropriate this program of reintroduction by making it accessible to all. For this purpose, we have created the eagle house, a space where symposiums, exhibitions, meetings, and scientific work will be held. The public will be able to see the birds thanks to a system of camera in the nests and to have explanations thanks to our animators. This house is located inside the eagle park, a few dozen meters from the reintroduction site. Its purpose is to offer a place of knowledge and research around the return of the fish eagles to the Geneva basin.

The webcams 

During the whole project, the birds will be observed by a system of cameras in the aviaries. These are accessible from any computer by purchasing a subscription to the program. They will also give the possibility to follow the birds from the eagle house for the public but also for the scientists studies which are led throughout the project.


Visit to the public :

The eagle house will be accessible to the public from 2022. We will keep you informed of the modalities as soon as they are put in place.

Starting in January 2022, the camera-based bird tracking system will be operational and will allow anyone who wishes to share in the moments of our birds’lives.

Sponsorship :

The fish eagle reintroduction program is entirely private, and it is only through the support of businesses and the public that we can keep the program running.

To this end, an annual subscription (in the form of a sponsorship) is proposed to you to have access to the cameras in the nests, the newsletters, the follow-up of the birds thanks to the GPS tags. An instructive and participative way to follow the return of the eagles on Lake Geneva from home with your family or for your own pleasure.

The partners


Richard Loomans Director of Veldhoven Zoo and 1st partner of the program.

His testimony: 

« I met Jacques-Olivier TRAVERS 12 years ago when he started his reintroduction program. I’m a bird lover since I’m young and one of my favorite bird is the white tailed sea eagle. When Jacques-olivier had explained me that White tailed disappeared from France and lake of Geneva 130 year ago, I decided immediatly to help him and support him. I’m proud to give to his program 2 of my breeding pairs. I’m aware that zoo have a responsability in leading conservation program as much as possible. My dream is to see many babies from Veldoven Zoo coming back into the wild. »