- Ocellated Crake
- Olive-backed Euphonia
- Olive-sided Flycatcher
- Olive-throated Parakeet
- Olive Sparrow
- Orange-bellied Euphonia
- Orange-billed Sparrow
- Orange-breasted Bunting
- Orange-breasted Fruiteater
- Orange-chinned Parakeet
- Orange-collared Manakin
- Orange-crowned Warbler
- Orange-fronted Parakeet
- Orange Oriole
- Orangequit
- Orchard Oriole
- Oriente Warbler
- Orinoco Saltator
- Oriole Blackbird
- Ornate Flycatcher
- Osprey
- Ovenbird