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

Amazona amazonica

Ramphocelus carbo

Ara chloropterus

Lipaugus vociferans

Ramphastos tucanus

Thraupis palmarum

Chelidoptera tenebrosa

Myiozetetes cayanensis

Progne chalybea

Icterus nigrogularis

Eupsittula pertinax

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