- Orkneys
- Ormtjernkampen National Park
- Ormtjernkampen National Park Norway
- Ornate Antwren
- Ornate Flycatcher
- Ornate Fruit-Dove
- Ornate Fruit Dove
- Ornate Hawk-Eagle
- Ornate Hawk Eagle
- Ornate Lorikeet
- Ornate Melidectes
- Ornate Stipplethroat
- Ornate Tinamou
- Ornithion
- Ornithion brunneicapillus
- Ornithion inerme
- Ornithion semiflavum
- Ornorectes
- Ornorectes cristatus
- Oroaetus
- Oroaetus isidori
- Orochelidon
- Orochelidon andecola
- Orochelidon flavipes
- Orochelidon murina
- Orphean Warbler
- Ortalis
- Ortalis araucuan
- Ortalis canicollis
- Ortalis cinereiceps
- Ortalis columbiana
- Ortalis erythroptera
- Ortalis garrula
- Ortalis guttata
- Ortalis leucogastra
- Ortalis motmot
- Ortalis poliocephala
- Ortalis ruficauda
- Ortalis ruficeps
- Ortalis squamata
- Ortalis superciliaris
- Ortalis vetula
- Ortalis wagleri
- Ortazzo and surrounding area
- Ortazzo and surrounding area Italy
- Orthogonys
- Orthogonys chloricterus
- Orthonychidae
- Orthonyx
- Orthonyx novaeguineae
- Orthonyx spaldingii
- Orthonyx temminckii
- Orthopsittaca
- Orthopsittaca manilata
- Orthopsittaca manilatus
- Orthorhyncus
- Orthorhyncus cristatus
- Orthotomus
- Orthotomus Sutorius
- Orthotomus atrogularis
- Orthotomus castaneiceps
- Orthotomus castaneiceps chloronotus
- Orthotomus chaktomuk
- Orthotomus chloronotus
- Orthotomus cinereiceps
- Orthotomus cuculatus
- Orthotomus cucullatus
- Orthotomus derbianus
- Orthotomus frontalis
- Orthotomus heterolaemus
- Orthotomus metopias
- Orthotomus moreaui
- Orthotomus nigriceps
- Orthotomus ruficeps
- Orthotomus ruficeps borneoensis
- Orthotomus samarensis
- Orthotomus sepium
- Orthotomus sericeus
- Orthotomus sutorius
- Ortolan Bunting
- Ortygospiza
- Ortygospiza atricollis
- Ortygospiza atricollis atricollis
- Ortygospiza fuscocrissa
- Ortygospiza gabonensis
- Ortygospiza locustella
- Ortyxelos
- Ortyxelos meiffrenii
- Oryzoborus
- Oryzoborus angolensis
- Oryzoborus atrirostris
- Oryzoborus crassirostris
- Oryzoborus funereus
- Oryzoborus maximiliani
- Oryzoborus nuttingi
- Osprey
- Ostfreisisches Wattenmeer (Waddensee National Park - Lower Saxony)
- Ostfriesisches Wattenmeer (Waddensee National Park - Lower Saxony)
- Ostrich
- Ostriches
- Otago Shag
- Otamendi National Reserve
- Otamendi National Reserve, Buenos Aires, Argentina(Otamendi National Reserve 70Km north Buenos Aires)
- Other Wildlife Portal
- Otididae
- Otidiformes
- Otidiphaps
- Otidiphaps nobilis
- Otis
- Otis tarda
- Otmoor
- Ottenby Nature Reserve (Öland)
- Ottenby Nature Reserve Öland
- Otus
- Otus Lawrencii
- Otus albogularis
- Otus alfredi
- Otus alius
- Otus angelinae
- Otus asio
- Otus atricapilla
- Otus atricapillus
- Otus bakkamoena
- Otus balli
- Otus barbarus
- Otus beccarii
- Otus brookii
- Otus brucei
- Otus capnodes
- Otus choliba
- Otus clarkii
- Otus collari
- Otus colombianus
- Otus cooperi
- Otus cyprius
- Otus elegans
- Otus elegans elegans
- Otus enganensis
- Otus everetti
- Otus flammeolus
- Otus fuliginosus
- Otus guatemalae
- Otus gurneyi
- Otus hartlaubi
- Otus hoyi
- Otus icterorhynchus
- Otus ingens
- Otus insularis
- Otus ireneae
- Otus jolandae
- Otus kennicottii
- Otus koepckeae
- Otus lawrencii
- Otus lempiji
- Otus lettia
- Otus leucotis
- Otus longicornis
- Otus madagascariensis
- Otus magicus
- Otus manadensis
- Otus mantananensis
- Otus marshalli
- Otus mayottensis
- Otus megalotis
- Otus mentawi
- Otus mindorensis
- Otus mirus
- Otus moheliensis
- Otus napensis
- Otus nigrorum
- Otus nudipes
- Otus pamelae
- Otus pauliani
- Otus pembaensis
- Otus petersoni
- Otus roboratus
- Otus roraimae
- Otus rufescens
- Otus rutilus
- Otus sagittatus
- Otus sanctaecatarinae
- Otus scops
- Otus scops cyprius
- Otus seductus
- Otus semitorques
- Otus senegalensis
- Otus siaoensis
- Otus silvicola
- Otus socotranus
- Otus spilocephalus
- Otus sulaensis
- Otus sunia
- Otus thilohoffmanni
- Otus trichopsis
- Otus umbra
- Otus usta
- Otus vermiculatus
- Otus watsonii
- Ou
- Oued Massa
- Oued Massa Morocco
- Ouessant (Ushant)
- Ouessant (Ushant) France
- Oulanka National Park
- Oulanka National Park Finland
- Ouse Washes Reserves
- Oustalet's Sunbird
- Oustalet's Tyrannulet
- Out Skerries
- Out Skerries Shetland Islands
- Out Skerries Shetland Islands, Scotland
- Outer Banks
- Outer Hebrides
- Ouvea Parakeet
- Ovambo Sparrowhawk
- Ovampo Sparrowhawk
- Ovenbird
- Ovre Anarjakka National Park
- Ovre Anarjakka National Park Norway
- Ovre Dividal National Park
- Ovre Dividal National Park Norway
- Ovre Pasvik National Park
- Ovre Pasvik National Park Norway
- Owl
- Owls
- Owston's Tit
- Oxbow National Wildlife Refuge
- Oxford Island, Lough Neagh
- Oxford Island, Lough Neagh Northern Ireland
- Oxfordshire
- Oxley Nature Center
- Oxley Nature Center(Near the Tulsa Internation Airport in Mohawk Park)
- Oxwich Bay
- Oxwich Bay Wales
- Oxylabes
- Oxylabes madagascariensis
- Oxylophus
- Oxylophus jacobinus
- Oxylophus levaillantii
- Oxypogon
- Oxypogon cyanolaemus
- Oxypogon guerinii
- Oxypogon lindenii
- Oxypogon stubelii
- Oxypogon stuebelii
- Oxyruncidae
- Oxyruncus
- Oxyruncus cristatus
- Oxyura
- Oxyura australis
- Oxyura ferruginea
- Oxyura jamaicensis
- Oxyura leucocephala
- Oxyura maccoa
- Oxyura vittata
- PATAGIOENAS CORENSIS
- PF80ED
- PF 65EDA
- PSITTACULA KRAMERI
- Pachycare
- Pachycare flavogrisea
- Pachycare flavogriseum
- Pachycephala
- Pachycephala albiventris
- Pachycephala arctitorquis
- Pachycephala aurea
- Pachycephala balim
- Pachycephala bonensis
- Pachycephala caledonica
- Pachycephala chlorura
- Pachycephala cinerea
- Pachycephala citreogaster
- Pachycephala collaris
- Pachycephala feminina
- Pachycephala flavifrons
- Pachycephala fulvotincta
- Pachycephala graeffii
- Pachycephala griseiceps
- Pachycephala griseonota
- Pachycephala grisola
- Pachycephala homeyeri
- Pachycephala hyperythra
- Pachycephala hypoxantha
- Pachycephala implicata
- Pachycephala inornata
- Pachycephala jacquinoti
- Pachycephala johni
- Pachycephala lanioides
- Pachycephala leucogastra
- Pachycephala leucostigma
- Pachycephala lorentzi
- Pachycephala macrorhyncha
- Pachycephala melanura
- Pachycephala mentalis
- Pachycephala meyeri
- Pachycephala modesta
- Pachycephala monacha
- Pachycephala nudigula
- Pachycephala occidentalis
- Pachycephala olivacea
- Pachycephala orioloides
- Pachycephala orpheus
- Pachycephala pectoralis
- Pachycephala pectoralis xanthoprocta
- Pachycephala phaionota
- Pachycephala philippinensis
- Pachycephala philippinensis philippinensis
- Pachycephala plateni
- Pachycephala raveni
- Pachycephala richardsi
- Pachycephala rufinucha
- Pachycephala rufiventris
- Pachycephala rufiventris falcata
- Pachycephala rufogularis
- Pachycephala schlegelii
- Pachycephala simplex
- Pachycephala soror
- Pachycephala sulfuriventer
- Pachycephala tenebrosa
- Pachycephala utupuae
- Pachycephala vanikorensis
- Pachycephala vitiensis
- Pachycephala xanthoprocta
- Pachycephalidae
- Pachycephalopsis
- Pachycephalopsis hattamensis
- Pachycephalopsis poliosoma
- Pachycoccyx
- Pachycoccyx audeberti
- Pachyphantes
- Pachyphantes superciliosus
- Pachyptila
- Pachyptila belcheri
- Pachyptila crassirostris
- Pachyptila desolata
- Pachyptila macgillivrayi
- Pachyptila salvini
- Pachyptila turtur
- Pachyptila vittata
- Pachyramphus
- Pachyramphus aglaiae
- Pachyramphus albogriseus
- Pachyramphus castaneus
- Pachyramphus castaneus intermedius
- Pachyramphus cinnamomeus


