Oehoe (Dutch)
Oeraluil (Dutch)
Oeverloper (Dutch)
Oeverpieper (Dutch)
Oeverzwaluw (Dutch)
Ooievaar (Dutch)
Ooievaarachtigen (Dutch)
Orpheusgrasmus (Dutch)
Orpheusspotvogel (Dutch)
Ortolaan (Dutch)
Olivaceous Warbler (English)
Olive-tree Warbler (English)
Orphean Warbler (English)
Ortolan Bunting (English)
Osprey (English)
Oedicnème criard (French)
Oie à bec court (French)
Oie cendrée (French)
Oie d'Egypte (French)
Oie de moissons (French)
Oie naine (French)
Oie rieuse (French)
Outarde canepetière (French)
Odinshühnchen (German)
Ohrenlerche (German)
Ohrentaucher (German)
Olivenspötter (German)
Orpheusgrasmücke (German)
Orpheusspötter (German)
Ortolan (German)
Oca collorosso (Italian)
Oca colombaccio (Italian)
Oca del Canada (Italian)
Oca egiziana (o del Nilo) (Italian)
Oca facciabianca (Italian)
Oca granaiola (Italian)
Oca lombardella (Italian)
Oca lombardella minore (Italian)
Oca selvatica (Italian)
Oca zamperosee (Italian)
Occhiocotto (Italian)
Occhione (Italian)
Orchetto marino (Italian)
Orco marino (Italian)
Organetto (Italian)
Organetto artico (Italian)
Ortolano (Italian)
Ortolano grigio (Italian)
Otarda (Italian)
Oca egipcia (Spanish)
Oropéndola (Spanish)
Ortega (Spanish)
Ostrero (Spanish)