
These are species with at least one recorded territory in Serbia, not a national checklist: a bird list from eBird or Avibase is more complete. The counts follow recording effort as much as wildlife, so a country with more visitors and more naturalists will show more of both.
The species with the most open occurrence records in Serbia, among those a photograph exists for. Most recorded is not most numerous: it rewards animals that are common, conspicuous and live where people go.

Corvus cornix

Parus major

Columba livia

Columba palumbus

Pica pica

Pelophylax lessonae

Corvus frugilegus

Chroicocephalus ridibundus

Microcarbo pygmaeus

Dendrocopos major

Phalacrocorax carbo

Cygnus olor
The reference database has no regions filed under Serbia.
The field guide covers Serbia on the map, but none of its species have an entry written for them yet.