- Sitta solangiae
- Sitta tephronota
- Sitta victoriae
- Sitta villosa
- Sitta whiteheadi
- Sitta yunnanensis
- Sittasomus
- Sittasomus griseicapillus
- Sittidae
- Sittiparus
- Sittiparus castaneoventris
- Sittiparus olivaceus
- Sittiparus owstoni
- Sittiparus semilarvatus
- Sittiparus varius
- Sittiparus varius castaneoventris
- Sittiparus varius varius
- Siva
- Siva cyanouroptera
- Sivrikaya
- Sivrikaya Turkey
- Six-wired Bird-of-paradise
- Six-wired Bird of paradise
- Six-wired Parotia
- Sjostedt's Barred Owlet
- Sjostedt's Greenbul
- Sjostedt's Owlet
- Sjostedt’s Barred Owlet
- Sjöstedt's Barred Owlet
- Sjöstedt's Greenbul
- Sjöstedt's Owlet
- Skaftafell National Park
- Skaftafell National Park Iceland
- Skagen
- Skagen Denmark
- Skallingen Nature Reserve
- Skallingen Nature Reserve Denmark
- Skokholm
- Skokholm Wales
- Skomer
- Skomer (Wales)
- Skomer Island
- Skomer Wales
- Skutchia
- Skutchia borbae
- Sky Lark
- Sladen's Barbet
- Slapton Ley
- Slate-blue Seedeater
- Slate-colored Antbird
- Slate-colored Boubou
- Slate-colored Coot
- Slate-colored Fox-Sparrow
- Slate-colored Fox Sparrow
- Slate-colored Grosbeak
- Slate-colored Hawk
- Slate-colored Seedeater
- Slate-colored Solitaire
- Slate-coloured Boubou Shrike
- Slate-coloured Fox-Sparrow
- Slate-coloured Fox Sparrow
- Slate-coloured Grosbeak
- Slate-coloured Hawk
- Slate-coloured Junco
- Slate-coloured Seedeater
- Slate-crowned Antpitta
- Slate-headed Parakeet
- Slate-headed Tody-Flycatcher
- Slate-headed Tody-Tyrant
- Slate-headed Tody Tyrant
- Slate-throated Gnatcatcher
- Slate-throated Redstart
- Slate-throated Whitestart
- Slaty-backed Chat-Tyrant
- Slaty-backed Chat Tyrant
- Slaty-backed Flycatcher
- Slaty-backed Forest-Falcon
- Slaty-backed Forest Falcon
- Slaty-backed Forktail
- Slaty-backed Gull
- Slaty-backed Hemispingus
- Slaty-backed Jungle-Flycatcher
- Slaty-backed Jungle Flycatcher
- Slaty-backed Nightingale-Thrush
- Slaty-backed Nightingale Thrush
- Slaty-backed Sparrowhawk
- Slaty-backed Tanager
- Slaty-backed Thornbill
- Slaty-backed Thrush
- Slaty-bellied Tesia
- Slaty-blue Flycatcher
- Slaty-breasted Rail
- Slaty-breasted Tinamou
- Slaty-breasted Wood-Rail
- Slaty-breasted Wood Rail
- Slaty-breasted Woodrail
- Slaty-capped Flycatcher
- Slaty-capped Shrike-Vireo
- Slaty-capped Shrike Vireo
- Slaty-chinned Longbill
- Slaty-crowned Antpitta
- Slaty-headed Longbill
- Slaty-headed Parakeet
- Slaty-headed Scimitar-Babbler
- Slaty-headed Scimitar Babbler
- Slaty-headed Tody-Flycatcher
- Slaty-headed Yuhina
- Slaty-legged Crake
- Slaty-mantled Goshawk
- Slaty-mantled Sparrowhawk
- Slaty-tailed Trogon
- Slaty-winged Foliage-gleaner
- Slaty Antwren
- Slaty Becard
- Slaty Blue Flycatcher
- Slaty Bristlefront
- Slaty Brush-Finch
- Slaty Brush Finch
- Slaty Brushfinch
- Slaty Bunting
- Slaty Cuckoo-Dove
- Slaty Cuckoo-shrike
- Slaty Cuckooshrike
- Slaty Egret
- Slaty Elaenia
- Slaty Finch
- Slaty Flowerpiercer
- Slaty Flycatcher
- Slaty Gnateater
- Slaty Monarch
- Slaty Robin
- Slaty Robin-flycatcher
- Slaty Spinetail
- Slaty Tanager
- Slaty Thicket-flycatcher
- Slaty Thrush
- Slaty Vireo
- Slavonian Grebe
- Slender-billed Babbler
- Slender-billed Black-Cockatoo
- Slender-billed Black Cockatoo
- Slender-billed Cicadabird
- Slender-billed Crow
- Slender-billed Cuckoo-Dove
- Slender-billed Cuckoo Dove
- Slender-billed Curlew
- Slender-billed Finch
- Slender-billed Flufftail
- Slender-billed Grackle
- Slender-billed Greenbul
- Slender-billed Gull
- Slender-billed Inezia
- Slender-billed Kite
- Slender-billed Miner
- Slender-billed Nutcracker
- Slender-billed Oriole
- Slender-billed Parakeet
- Slender-billed Prion
- Slender-billed Red-winged Starling
- Slender-billed Scimitar-Babbler
- Slender-billed Scimitar Babbler
- Slender-billed Starling
- Slender-billed Thornbill
- Slender-billed Tyrannulet
- Slender-billed Vulture
- Slender-billed Weaver
- Slender-billed White-eye
- Slender-billed Wren
- Slender-billed Xenops
- Slender-footed Tyrannulet
- Slender-tailed Cisticola
- Slender-tailed Nightjar
- Slender-tailed Woodstar
- Slender Antbird
- Slender Sheartail
- Slender billed Cuckoo Dove
- Slender billed Gull
- Slimbridge
- Slimbridge Wildfowl and Wetlands Trust Reserve
- Slonsk Reserve
- Slonsk Reserve Poland
- Slovakia
- Slovenia
- Small-billed Asity
- Small-billed Crow
- Small-billed Elaenia
- Small-billed False Sunbird
- Small-billed Tinamou
- Small-headed Elaenia
- Small Andaman Drongo
- Small Blue Kingfisher
- Small Buttonquail
- Small Coucal
- Small Cuckoo
- Small Flowerpecker
- Small Green Barbet
- Small Grey Flycatcher
- Small Ground-Finch
- Small Ground-Sparrow
- Small Ground Finch
- Small Ground Sparrow
- Small Hawk-Cuckoo
- Small Hawk Cuckoo
- Small Indian Pratincole
- Small Iora
- Small Lifou White-eye
- Small Lifu White-eye
- Small Minivet
- Small Mountain Honeyeater
- Small Niltava
- Small Pratincole
- Small Salmon Arab
- Small Salmon Arab Butterfly
- Small Skylark
- Small Slaty Flycatcher
- Small Slaty Monarch
- Small Snowfinch
- Small Sparrowhawk
- Small Tree-Babbler
- Small Tree-Finch
- Small Tree Babbler
- Small Tree Finch
- Small Whitethroat
- Small Wren-Babbler
- Small Wren Babbler
- Smaller Banded Snake Eagle
- Smaller Red-headed Babbler
- Smaller Red-headed Tree-Babbler
- Smaller Red-headed Tree Babbler
- Smardale Gill
- Smew
- Smicrornis
- Smicrornis brevirostris
- Smith's Longspur
- Smithornis
- Smithornis capensis
- Smithornis rufolateralis
- Smithornis sharpei
- Smoke-colored Pewee
- Smoke-coloured Pewee
- Smoke Coloured Pewee
- Smokey Brown Woodpecker
- Smokey Bush Tyrant
- Smoky-Brown Woodpecker
- Smoky-brown Woodpecker
- Smoky-fronted Tody-Flycatcher
- Smoky-fronted Tody Flycatcher
- Smoky Brown Woodpecker
- Smoky Bush-Tyrant
- Smoky Bush Tyrant
- Smoky Honeyeater
- Smoky Robin
- Smoky Warbler
- Smola
- Smooth-billed Ani
- Smooth Billed Ani
- Smutsornis
- Smutsornis africanus
- Smøla
- Snail-eating Coua
- Snail Kite
- Snail Lake - Vadnais Lake Regional Park(Vadnais Heights, MN)
- Snake-Eagle
- Snake-Eagles
- Snake Eagle
- Snake Eagles
- Snares Crested Penguin
- Snares Island Snipe
- Snares Penguin
- Snares Snipe
- Snares snipe
- Snethlage's Antpitta
- Snethlage's Tody-Tyrant
- Snethlage's Tody Tyrant
- Snethlage’s Antpitta
- Snettisham
- Snettisham RSPB Reserve
- Snoring Rail
- Snow-capped Manakin
- Snow Bunting
- Snow Goose
- Snow Mountain Mannikin
- Snow Mountain Munia
- Snow Mountain Quail
- Snow Mountain Robin
- Snow Mountains Quail
- Snow Mountains Robin
- Snow Partridge
- Snow Petrel
- Snow Pigeon
- Snow Robin
- Snowcap
- Snowcock
- Snowcocks
- Snowornis
- Snowornis cryptolophus
- Snowornis subalaris
- Snowy-bellied Hummingbird
- Snowy-breasted Hummingbird
- Snowy-browed Flycatcher
- Snowy-browed Nuthatch
- Snowy-cheeked Laughing-thrush
- Snowy-cheeked Laughingthrush
- Snowy-crowned Robin-Chat
- Snowy-crowned Robin Chat
- Snowy-crowned Tern
- Snowy-throated Babbler
- Snowy-throated Kingbird
- Snowy Albatross
- Snowy Cotinga
- Snowy Egret
- Snowy Owl
- Snowy Plover
- Snowy Sheathbill
- Snowy plover
- Soberania National Park
- Soberanía National Park
- Sociable Lapwing
- Sociable Plover
- Sociable Weaver
- Social Flycatcher
- Social Weaver
- Society Islands Monarch
- Society Islands Reed-Warbler
- Society Islands Reed Warbler
- Society Kingfisher
- Socorro Dove
- Socorro Mockingbird
- Socorro Parakeet
- Socorro Wren
- Socotra
- Socotra Bunting
- Socotra Buzzard
- Socotra Chestnut-winged Starling
- Socotra Cisticola
- Socotra Cormorant
- Socotra Golden-winged Grosbeak
- Socotra Grosbeak
- Socotra Mountain Bunting
- Socotra Red-winged Starling
- Socotra Scops-Owl
- Socotra Scops Owl
- Socotra Sparrow
- Socotra Starling
- Socotra Sunbird


