
These are species with at least one recorded territory in Congo - Kinshasa, 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 Congo - Kinshasa, among those a photograph exists for. Most recorded is not most numerous: it rewards animals that are common, conspicuous and live where people go.

Praomys jacksoni

Hybomys univittatus

Pogoniulus bilineatus

Gypohierax angolensis

Cisticola chubbi

Pycnonotus barbatus

Motacilla aguimp

Cossypha heuglini

Passer griseus

Ploceus baglafecht

Lanius humeralis

Turtur afer
The reference database has no regions filed under Congo - Kinshasa.
The field guide covers Congo - Kinshasa on the map, but none of its species have an entry written for them yet.