Златозар Боев [Zlatozar Boev]
31 December 1991 · volume 4
· pp. 47–56 · PDF [full text]
[no abstract available originally]
[Summary]: The studied material originates from 19 nesting sites of the species in Strandzha mountain (South-East Bulgaria). It was collected in 1988-1989 and comprises of 2787 bones and bone fragments of birds, belonging to 80 taxa, 65 of them determinated to the species level. Twenty-seven species of birds are established for the first time as food components of the Eagle Owl in Bulgaria. Bubo bubo takes part in the alimentary interactions with more than 1/4 of the species composition of the local avifauna. Perdix perdix and Columba livia domestica are of greater importance as victims. They consist of about 1/3 of the total number of caught bird specimens and consumed meat of birds. The most common victims are species with body mass between 100 and 500 grams. These species provide 45 per cent of the bird meat, and amount 56,6 per cent of the total number of killed birds (473 specimens). The small passeriform birds are more rare prey and amount 1,87 per cent of the meat of victims. The role of the hydrophylic (water) avifauna is considerable — 8,7 per cent of specimens and 12,5 per cent of the mass of victims. The smallest birds established in pellets are sparrows (Passer domesticus montanus), and the largest ones are Meleagris gallopavo domesiica and Anser anser. The Eagle Owl is practically harmless for domestic birds in the region, which consist of 2,9 per cent of specimens during the studied period. The species can not be considered as an eminent enemy of game fowl (they amount less than 1/5 of the total number of caught birds). Four species of owls and 3 species of diurnal raptors (falconiform birds), are established in the food spectrum also. Two cases of canibalism (kainism) are established as well. The average number of the preserved bones of each caught bird is 5,9 which means that less than 5 per cent of the total number of bones of the birds-victims are represented in the collected material. The bone fragments usually have dimensions 1,5 to 3,5 cm. while almost half of the long bones of the limbs are entirely preserved unbroken. As a comparatively polyphagous species of Order Strigiformes, the Eagle Owl reaches the highest level of specialization in relation to ornithophagy. That is why, having in mind its wide range in Palearctic, Bubo bubo is a very suitable species for monitoring researches of the terrestrial environment.