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

Poecile atricapillus

Corvus brachyrhynchos

Turdus migratorius

Larus delawarensis

Branta canadensis

Anas platyrhynchos

Spinus tristis

Melospiza melodia

Sturnus vulgaris

Agelaius phoeniceus

Cardinalis cardinalis

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