This study presents the results of conservation measures undertaken and their impact on the eastern imperial eagle population in Bulgaria. The species is distributed in the south-eastern part of the country, as there is only one known pair in central Bulgaria. During the period 2009-201 3, 28 different breeding territories were occupied. The population increased by 20%, as the number of pairs that occupied breeding territories increased from 20 in 2009 to 24 in 201 3. In general, the mean values of the breeding parameters of the eastern imperial eagle population for the period 2009-201 3 were as follows: productivity (P) 1 .03±0.1 8; breeding success (BS) 1 .1 8±0.21 ; and fledgling success (FS) 1 .68±0.1 6. The annual survival rate of breeders varied from 0.795 to 0.932. The most important factor causing the mortality of immature eagles was electrocution. Shooting and poisoning have become important mortality factors, too. Guarded pairs had a higher mean breeding success (1 .32±0.88) than non-guarded pairs (1 .06±0.91 ). As a whole, 39% of all artificial nests installed in the period 2009-201 3 were occupied by birds of different species. During the period 2008-201 3, a total of 23 juvenile eastern imperial eagles were tagged with satellite/GPS transmitters. In addition, 608 hazardous electric poles in the territories of seven pairs were insulated. Supplementary feed was provided for 1 4 pairs once a week during the autumn-winter seasons (October - March). A total of 483 supplementary feedings took place, 450 ofwhich also included monitoring in order to record the effectiveness of this activity.
Assessing whether conservation management actions are effective requires a good understanding of the demographic parameters that contribute to the population growth rate. Among the key demographic parameters influencing a population, immigration is one of the most difficult to measure empirically but may mask or accentuate the effects of conservation measures. We use an integrated population model to assess whether a population increase of a large raptor species can be explained by high fecundity and survival resulting from local conservation measures, or whether immigration may have contributed to population growth. We monitored the Eastern Imperial Eagle (Aquila heliaca) population in Bulgaria from 1998 to 2014, and tracked juveniles using satellite transmitters to estimate survival probability over the first three years of life. We used intensive territory monitoring of breeding birds to estimate survival probabilities and fecundity of birds older than 3 years. The Imperial Eagle population in Bulgaria increased by about 11 % per year between 1998 and 2014 (k = 1.111, 95 % credible interval 1.076-1.156). While local conservation measures have succeeded in reducing nest loss and the mortality of adults (adult survival = 0.924; 0.887-0.955), high mortality of juveniles during their first year of life resulted in only 12 % of fledglings surviving to adult age. Based on these survival probabilities and the estimated fecundity of breeding pairs in Bulgaria (1.063; 0.932-1.203), some immigration may have contributed to the population growth in Bulgaria. Because the integrated population model accounts for all the uncertainty associated with disparate data sources, the estimated immigration rate was too Communicated by
A long-living species like A. heliaca has a natal dispersal period lasting several years. This period is crucial for the survival and conservation of the eagles. In this study we present mortality factors and the survival rate of juvenile and immature A. heliaca from Bulgaria as established by satellite telemetry. A total of 20 juvenile A. heliaca were fitted with GPS/Argos transmitters in their nests in Bulgaria. Fourteen birds were tracked till their death and the bodies were found. Tracking allows the survival rate of juvenile and immature A. heliaca to be estimated for the first time. It is 59.1% for the first calendar year, 83.3% for the second calendar year and 80.0% for the third calendar year. The main mortality factor for juvenile and immature A. heliaca from the Bulgarian population is electrocution, which caused 59.0% of the mortality cases. Other threats identified are shooting, poisoning and collisions. Most of the fatalities of these tracked eagles occurred in Bulgaria (50%) and Turkey (43%). Thus, Turkey is a key country for conservation of the Bulgarian population ofA. heliaca during its dispersal period. Eagles from Bulgaria have been recorded dispersing further south, to Sudan and Saudi Arabia. Conservation efforts are needed both inside and outside Bulgaria in order to reduce mortality. International collaboration and the exchange of experiences should be part of any conservation strategy or plans focused on the eastern imperial eagle.
Summary The Eurasian Griffon Vulture Gyps fulvus is a large Palearctic, Indohimalayan and Afrotropical Old-World vulture. The species’ range is vast, encompassing territories from the Pyrenees to the Himalayas. We reviewed and analysed a long-term data set for Griffon Vulture in the Balkans to estimate the change in its population size and range between 1980 and 2019. After a large historical decline, the Griffon Vulture population slightly increased in the last 39 years (λ = 1.02) and reached 445–565 pairs in 2019. We recorded a gradual increase of Griffon Vulture subpopulations in Serbia (λ = 1.08 ± 0.003), Bulgaria (λ = 1.08 ± 0.003) and Croatia (λ = 1.05 ± 0.005) and steep to a moderate decline of the species subpopulations in Greece (λ = 0.88 ± 0.005) and North Macedonia (λ = 0.94 ± 0.01). However, species range contracted to half of its former range in the same period. It occurred in 42 UTM squares in the 1980–1990 period and only 20 UTM squares between 2011 and 2019 and concentrated into three source subpopulations in Bulgaria, Serbia, and Croatia. Following reintroductions of the Griffon Vulture in Bulgaria, new colonies were formed at three novel localities after 2010. Regular movements of individuals between the different subpopulations exist nowadays. Therefore, preservation of both current and former core areas used for breeding and roosting is essential for species conservation in the region. However, the Griffon Vulture still faces severe threats and risk of local extinction. Various hazards such as poisoning, collision with energy infrastructure, disturbance and habitat alteration are depleting the status of the Balkan population and its full recovery. Further studies should analyse age-specific survival and mortality, recruitment, genetic relatedness, spatial use to inform the viability of this population in the future.
© Raptor Protection ofSlovakia (RPS) 17 Distribution, abundance, breeding parameters, threats and prey preferences of the eastern imperial eagle (Aquila heliaca) in European Turkey Rozšírenie, početnosť, hniezdne parametre, hrozby a potravné preferencie orla kráľovského (Aquila heliaca) v európskej časti Turecka Dimitar DEMERDZHIEV, Dobromir DOBREV, Süreyya ISFENDIYAROĞLU, Zlatozar BOEV, Stoycho STOYCHEV, Nikolay TERZIEV & Svetoslav SPASOV Abstract: During the period 2008-2013, 32 different breeding territories were occupied by eastern imperial eagles (EIEs). These territories were mainly distributed in two regions: the Dervent Heights / Yıldız Mts. and the area to the north of the Marmara sea coast. The nearest neighbour distance established was 4.2 km. The mean distance between pairs was 10.44±2.95 km. The mean value of breeding success for the period 2008-2013, including 107 cases of incubation, was 1.01±0.10. The mean breeding success of birds in the Marmara region (1.05±0.78) was higher than that in the Dervent Heights / Yıldız Mts. (0.91±0.84). The present study on the diet of the EIE was based on the remains of 582 prey items of at least 70 taxa. Mammals were the most common group (46.5%), followed by birds (32.4%) and reptiles (20.3%). The white-breasted hedgehog (Erinaceus roumanicus) was the most common prey, followed by two tortoises -Hermann's tortoise (Eurotestudo hermanni) and the Greek tortoise (Testudo graeca) -which together accounted for a total of 14.4% of the prey caught. The prey species particularly represented in the food spectrum of the studied pairs were: the yellow-legged gull (Larus michahellis), the European souslik (Spermophilus citellus), the chicken (Gallus gallus f. domestica) and the white stork (Ciconia ciconia). These species together accounted for 67.8% of the prey caught. There was a statistically significant difference (Z=2.52, p=0.01) in the food preferences of the EIEs in the two studied regions.Abstrakt: V období 2008-2013 bolo orlami kráľovskými obsadených 32 rôznych hniezdnych teritórií. Tieto územia sa nachádza-jú najmä v dvoch oblastiach: pohorie Derventa / Yıldız a územie na sever od Marmarského mora. Najbližšia vzdialenosť medzi hniezdiskami bola 4,2 km. Stredná vzdialenosť medzi pármi bola 10,44 ± 2,95 km. Priemerná hodnota hniezdnej úspešnosti v období 2008-2013 vrátane 107 prípadov inkubácii bola 1,01±0,10. Priemerná hniezdna úspešnosť vtákov v Marmarskom regióne (1,05±0,78) bola vyššia ako v oblasti pohorí Derventa / Yıldız (0,91±0,84). Predkladaná štúdia potravy orla kráľovského bola založená na 582 zvyškoch koristi, obsahujúcej minimálne 70 taxónov. Cicavce boli najrozšírenejšie skupinou (46.5 %), nasledované vtákmi (32,4 %) a plazmi (20,3 %). Najčastejšou korisťou bol jež bledý (Erinaceus roumanicus) a dva druhy korytnačiek -korytnačka zelenkastá (Eurotestudo hermanni) a korytnačka grécka (Testudo graeca), ktoré dohromady predstavovali celkom 14,4 % z ulovenej koristi. Potravné spektrum sledovaných párov obsahoval tieto druhy koristi: čajka žltonohá (Larus ...
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