Diet composition of the long-legged buzzard (Buteo rufinus) in southeastern Bulgaria

Abstract During 2018–2022, the local breeding population of the long-legged buzzard (Buteo rufinus) in southeastern Bulgaria was monitored in the territory of three districts of Sliven, Yambol and Burgas. Diet data were collected in 15 breeding pairs. Overall, we identified 290 prey items. We used three methods for diet analysis that produced different results: (1) collecting prey remains (68 individuals, 23.5%), (2) collecting pellets and skeletal materials (42 individuals, 14.5%), and (3) collecting data on a diet using trail cameras (180 individuals, 62.1%). The dominant part of the diet formed mammalian species (69.3%, ten species and some undetermined Rodentia and other Mammalia). Birds were less represented but with similar species richness (21.0%, 11 species and pigeons (Columba sp.), thrushes (Turdus sp.), undetermined Passeriformes and Galliformes). Compared to birds, the proportion of Reptilia was lower (9.3%, two species). Amphibia were represented only with one specimen of the common toad (Bufo bufo). The dominant diet of long-legged buzzards in southeastern Bulgaria was European souslik (Spermophilus citellus, 31.0%), followed by sibling vole (Microtus mystacinus, 25.5%). Less abundant taxa were undetermined Passeriformes (6.9%), lesser mole rat (Nannospalax leucodon, 5.9%), pigeons (4.5 %), blotched snake (Elaphe sauromates, 3.8%), Balkan green lizard (Lacerta trilineata, 3.5%), European hare (Lepus europaeus, 3.1%), common magpie (Pica pica, 2.8%), Colubridae (1.7%), common blackbird (Turdus merula, 1.4%), domestic chicken (Gallus gallus domesticus, 1.0%) and Eurasian skylark (Alauda arvensis, 1.0%). Spermophilus citellus was the most abundant species in the Yambol district samples and the most abundant species in the data obtained from trail cameras. In the Burgas district, the dominant species was Microtus mystacinus. When comparing the diet spectrum of Buteo rufinus from other authors, birds occurred more frequently than reptiles in our material.