Comparison on the Prey Remains of Reintroduced Lesser Kestrels (Falco naumanni Fleischer, 1818) Colonies in Bulgaria

This study presents preliminary data on the diet composition of reintroduced Lesser Kestrels (Falco naumanni) in two restored colonies in Bulgaria—near Stara Zagora and in the Sakar Mountains at Levka village—based on pellet analysis. A total of 103 and 48 identifiable prey items (occurrences in the pellets) were recovered from the respective sites. Insects (particularly Coleoptera) dominated the diet at both colonies, but some differences were observed in the occurrence of vertebrate prey. Birds (Aves) were the second most common category in Stara Zagora, while small mammals (Mammalia) were more prevalent in Sakar. Annelids were detected only in Stara Zagora, and millipedes (Diplopoda) only in Sakar. Synthetic materials were found in pellets from Stara Zagora, suggesting plastic ingestion. Levins’ index indicated similar niche breadths (1.915 vs. 2.008), and Pianka’s index showed a high dietary overlap (0.981), pointing to broadly similar trophic preferences despite local prey availability.