Connecting Europe and Asia: The Neogene birds of Bulgaria and their paleoenvironmental and paleornithogeographical significance

Seventeen Neogene avian localities are documented in Bulgaria, including 12 Miocene and 5 Pliocene sites, distributed across lowland and semi-mountainous regions of both Northern and Southern Bulgaria. The known avifauna comprises 24 taxa, including three new genera — Euroceros (ground hornbill), Balcanas (dabbling duck), and Eremarida (lark) — and 11 new species, highlighting the previously underestimated diversity of Neogene birds in Southeastern Europe.
   In addition to its taxonomic significance, the Bulgarian Neogene avifauna provides important insights into paleornithogeographic patterns in the Eastern Paratethys region. The composition of these assemblages indicates faunal affinities with both Western Eurasian and, to a lesser extent, Asian provinces, supporting the role of the Balkan region as a biogeographic corridor during the Neogene.
   In a broader context, Bulgarian fossil birds represent a small but non-negligible fraction of the global Neogene avifauna, accounting for approximately 1.0 % of known taxa. Their stratigraphic distribution and taxonomic composition, however, suggest that the region preserves key evidence for avian dispersal and diversification in Southeastern Europe. These findings emphasize the importance of the Balkan Peninsula as an underexplored area with significant potential for refining Neogene avian paleobiogeography.