Identifying the home range of breeding pairs of Eastern Imperial Eagle (Đ?quila heliaca heliaca) through radio-tracking in Bulgaria Gradimir Gradev – Green Balkans www.greenbalkans.org, ggradev@greenbalkans.org
VII. International Conference for the Conservation of the Eastern Imperial Eagle Bratislava, Slovakia 02-05/10/2013
Size of the Imperial Eagle breeding territory in Bulgaria according to bibliographic data
• - 40 sq.km. (Simeonov, Petrov, 1980) • - 75 sq.km. - based on the mean distance between breeding pairs (Stoychev et al. 2010) • - 78,5 sq.km. – a hypothetical mean area occupied by an Imperial Eagle pair – within a 5 km radius around the nest (Demerdzhiev 2011)
• The study was implemented in 2010 and 2011. • Two juvenile Imperial Eagles tagged by Green Balkans in 2007 and 2008 were tracked. • The birds were tagged at the age of about 60 days, prior to fledging.
• Attachment of radio-transmitter – standard methodology – “backpack” • Standard ornithological and PVC rings
• VHF Radio-transmitter – Biotrack ТW 3 – 69 g • Antennae - TVP Y-4FL 150 - 152 mHz • Receiver - Communications Specialists Inc. R1000 Telemetry Receiver
- Victor (Eagle 2) – Tagged in 2007 in Western Strandzha – the first Imperial Eagle tagged with a transmitter in the country. - During the first winter period Victor stayed in Bulgaria.
- Gabriela (Eagle 3) – Tagged in 2008 in Sakar
- Gabriela migrated southward during the first winter period.
Results
• Victor formed a pair and started breeding in 2010 - in its third year – the first confirmed breeding attempt of a tagged Imperial Eagle in the country. • The female partner was at a similar age.
• The bird occupied an artificial nest built in the region by Green Balkans as a result of the radio-tracking implemented earlier (Gradev et al., 2011) – this was the first case of an Imperial Eagle occupying an artificial nest in Bulgaria.
• Victor’s pair hatched one chick, which was raised successfully by its parents. • Despite the provided nest guarding, the chick was stolen by poachers prior to fledging.
• In 2011, Victor occupied another artificial nest built by Green Balkans and raised two chicks • One of the chicks was hatched in the nest, while the other, which had been hatched in another nest and then rescued, was placed in Victor’s nest to be raised there.
• Gabriela, the other radio-tagged eagle, also formed a pair and started breeding in its third year (2008). • Although incubating for a long time, some 40 days later the bird abandoned the clutch, probably due to the inexperience of both partners.
Conclusions • The home range of the Imperial Eagle was identified for the first time in Bulgaria by tracking radio-tagged birds. • Confirmed breeding attempts of Imperial Eagles at the age of 3, including a case of successful breeding. • The tagged Imperial Eagles demonstrated philopatry toward their population, especially Victor.
Thank you for your attention!