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Results from experimental fostering of a captive-bred Egyptian vulture chick in a wild nest in Bulgaria

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Fostered chick in nest at the Wildlife Rescue Centre of Green Balkans
Fostered chick in nest at the Wildlife Rescue Centre of Green Balkans

As part of the conservation of Egyptian vultures in the Balkans, the Egyptian Vulture New LIFE project has been testing different techniques of releasing captive-bred birds, including the traditional hacking and delayed release techniques. We have been working with the project team and in collaboration with the Egyptian Vulture Captive Breeding Network (EEP) on a new technique being tested, fostering chicks in wild nests, and can now report on the first results.   

Fostering technique

Fostering of chicks into nests has been demonstrated as a successful method for restocking of birds of prey populations in many conservation projects. Тhe method involves placing captive-bred or wild chicks in wild nests with foster parents. In order for this technique to be successful there are many issues that need to be considered such as; the age of both wild and fostered chicks, detailed before- and after-intervention monitoring of the nests targeted for fostering, including investigation of bird’s behavior, and readiness to react quickly in the presence of a problem. 

For the Egyptian vulture, this method has so far been used in the captive breeding programs, but its application in the wild is rare – to our knowledge, it had only been tried once in Italy before.

From Prague to Bulgaria

Working with the Egyptian Vulture New LIFE team we here at the Vulture Conservation Foundation have supported the experimental use of this technique and a young captive-bred Egyptian vulture was donated to the project by Anton Vaidl – coordinator of the European Endangered Species Programmes (EEP) of the European Association of Zoos and Aquaria (EAZA), and also a VCF advisory board member. 

After traveling from Prague Zoo, a two-week old chick was placed into the nest of a pair of  wild Egyptian vultures in the Eastern Rhodopes mountains, Bulgaria by a team of experienced colleagues from the Bulgarian Society for the Protection of Birds and Green Balkans. The foster birds already had one chick, a few days younger than the fostered one, an age difference that is normal for hatchlings from the same brood.

Intervening to protect the chicks

Soon after the placement of the young captive-bred bird, the team continued to monitor closely the nest and noticed unexpected and unusually aggressive behaviour of the fostered chick towards the wild chick. Despite the visit of the male adult bird and his attempt to feed the two chicks, the aggressive behavior of the fostered vulture continued. This required urgent intervention to protect the wild nestling, and the decision was taken to collect again the captive-bred individual, which was then transferred to the Wildlife Rescue Centre of Green Balkans in Stara Zagora.

There it was placed in the nest of a captive Egyptian vulture breeding pair, who had successfully bred for the first time this year. However, the fostered chick continued to exhibit aggressive behaviour. 

This level of aggressive behaviour is uncharacteristic for Egyptian vulture chicks and can possibly be attributed to the length of time spent in transit from Prague, and/or to the individual characteristics of the young bird, rather than competition for food between the two chicks in the nest. The staff at the Green Balkans Rescue Centre were forced to intervene and remove the chick, and feed it before deciding to return it to the nest. This second time the bird was successfully accepted by the foster parents. 

The young chick will now be released into the wild using another technique, most probably the hacking method by placing it in an artificial enclosed surrogate nest where it will be fed (without any human contact) and looked after from a monitoring point in the distance until it fledges. 

These results – although not too positive, are very important for us to understand and evaluate different release techniques, that could be used in the future, should we decide that restocking or reintroduction of captive-bred Egyptian vultures is a valuable conservation tool. We will be analysing these results to plan further tests in the future.

The Egyptian Vulture New LIFE 

The Egyptian Vulture New LIFE aims to reinforce the Egyptian vulture population in their Europe’s easternmost range across the Balkans. By actively managing and restocking the population by releasing captive-bred birds the project will support the small Balkan population which number between 60 and 80 pairs across the whole region. The project is working to deliver conservation measures that eliminate major known threats such as illegal poisoning and electrocution in their summer breeding grounds. Monitoring the population closely using GPS transmitters will also help the project tackle the major threats Egyptian vultures face.  The Egyptian Vulture New LIFE is a partnership of organisations, led by the Bulgarian Society for the Protection of Birds and Bulgarian conservation organisation Green Balkans,from 14 countries spanning Europe, the Middle East and Africa, to protect Egyptian vultures not only in Europe but all along their migratory flyway.

You can follow the progress of the project by visiting the Egyptian Vulture New LIFE website. 

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