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

Phylloscopus trochilus

Regulus regulus

Erithacus rubecula

Cyanistes caeruleus

Parus major

Acrocephalus scirpaceus

Ficedula hypoleuca

Spinus spinus

Acanthis flammea

Emberiza schoeniclus

Calidris alpina

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