Oreopsittacus, [363]

Oreortyx pictus, [230] f.

Oreoscoptes, [514], [515], [519]

Oreotrochilus, [431] f., [436];

O. chimborazo, [428];

O. pichincha, [428], [430], [436]

Organ-bird, [522], [532]

Oriental Region, [17]

Origma, [517], [518]

Oriole, [542] f.;