Diet is not related to productivity but to territory occupancy of the Egyptian vulture on the Balkans

22.01.2015

© Svetoslav Spasov, www.NatureImages.eu

In the Balkans, the Egyptian vulture population is declining more rapidly than elsewhere in Europe, with 80% decrease in the numbers in the last 30 years (Velevski et al. 2015). Changes in diet composition and diversity could explain this negative trend, but so far the relationship between diet and demographic parameters of the population are poorly studied.

Study on the changes in the diet of Egyptian vulture in the last 9 years in Bulgaria and Greece and its relationship with productivity and territory occupancy was held within the frames of the LIFE+ project The Return of the Neophron. A total of 3,237 food remains from 63 different nest sites in 51 breeding territories were collected in the period 2005–2013.

The results show that the diet of the Egyptian vulture on the Balkans is very diverse (consisted of 136 species from 32 orders), with mammals presented the most (49%), followed by reptiles (28%) and birds (22%), and the rest animal groups consisting in total of about 1%. The wild animals dominated in the diet (71%), and at species level the commonset species being the Greek tortoise (Testudo graeca, 13%), Hermann's tortoise (Eurotestudo hermanni, 11%)  and the domestic chicken (Gallus gallus f. domestica, 7%). The diet diversity has not changed significantly over the last 9 years and does not differ between countries, but it was significantly higher in northern Bulgaria compared to southern Bulgaria and Greece. There was no relationship found between the diet and productivity, but negative relationship between dietary diversity and territory occupancy rate - the diet was significantly broader in birds that abandoned their territories earlier.

In conclusion, it is unlikely that dietary limitations on reproductive output are a critical threat to Egyptian vultures on the Balkan Peninsula. The negative relationship between dietary diversity and territory occupancy rate may be due to a higher susceptibility of adults to poisoning, and more information on the effect of diet availability on adult and juvenile survival would be useful to inform and improve conservation management actions. Providing safe food for Egyptian vultures in the short term, seems an urgent and effective conservation measure for decreasing the risk of poisoning and increasing the persistence of the population in the core areas.

 

The technical report could be downloaded from here.

Dobrev, V., Boev, Z., Oppel, S., Arkumarev, V., Dobrev, D., Kret, E., Vavylis, D., Saravia, V., T.,
Bounas, A. & Nikolov, S.C. 2015. Diet of the Egyptian vulture (Neophron percnopterus) in
Bulgaria and Greece (2005-2013). Technical report under action A5 of the LIFE+ project “The
Return of the Neophron” (LIFE10 NAT/BG/000152). BSPB, Sofia. 28 p.

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