Ochre-naped ground tyrant 
Oleaginous hemispingus 
Olivaceous flatbill 
Olivaceous greenlet 
Olivaceous siskin 
Olivaceous woodcreeper 
Olive bushshrike 
Olive finch 
Olive flycatcher 
Olive Oropendola 
Olive sparrow 
Olive sunbird 
Olive tanager 
Olive Thrush 
Olive-backed euphonia 
Olive-backed foliage-gleaner 
Olive-backed oriole 
Olive-backed pipit 
Olive-backed sunbird 
Olive-backed woodcreeper 
Olive-bellied sunbird 
Olive-crowned Yellowthroat 
Olive-green tanager 
Olive-sided flycatcher