- Short-billed Tanager Finch
- Short-billed Tetraka
- Short-browed Owl
- Short-clawed Lark
- Short-collared Nighthawk
- Short-crested Coquette
- Short-crested Flycatcher
- Short-crested Monarch
- Short-crested Myna
- Short-eared Owl
- Short-legged Ground-Roller
- Short-legged Ground Roller
- Short-tailed Albatross
- Short-tailed Antthrush
- Short-tailed Babbler
- Short-tailed Batis
- Short-tailed Crow
- Short-tailed Diuca-finch
- Short-tailed Diuca Finch
- Short-tailed Emerald
- Short-tailed Field-Tyrant
- Short-tailed Field Tyrant
- Short-tailed Finch
- Short-tailed Frogmouth
- Short-tailed Glossy Starling
- Short-tailed Grasswren
- Short-tailed Green Magpie
- Short-tailed Hawk
- Short-tailed Jungle-Babbler
- Short-tailed Jungle Babbler
- Short-tailed Lark
- Short-tailed Magpie
- Short-tailed Nighthawk
- Short-tailed Paradigalla
- Short-tailed Parrot
- Short-tailed Parrotbill
- Short-tailed Pipit
- Short-tailed Pygmy-Tyrant
- Short-tailed Pygmy Tyrant
- Short-tailed Scimitar-Babbler
- Short-tailed Scimitar Babbler
- Short-tailed Shearwater
- Short-tailed Sicklebill
- Short-tailed Starling
- Short-tailed Swift
- Short-tailed Wattle Bird
- Short-tailed Woodstar
- Short-tailed Wren-Babbler
- Short-tailed Wren Babbler
- Short-toed Coucal
- Short-toed Eagle
- Short-toed Nuthatch Vanga
- Short-toed Rock-Thrush
- Short-toed Rock Thrush
- Short-toed Snake-Eagle
- Short-toed Snake Eagle
- Short-toed Treecreeper
- Short-winged Cisticola
- Short-winged Cuckoo
- Short-winged Grebe
- Short Eared Owl
- Short Tailed Hawk
- Shovel-billed Kookaburra
- Shoveler
- Shovelers
- Shrenck's Little Bittern
- Shrike-like Cotinga
- Shrike-like Tanager
- Shrike-like Thickhead
- Shropshire
- Shy Albatross
- Shy Ground Dove
- Shy Heathwren
- Shy Hylacola
- Shy Mollymawk
- Sialia
- Sialia Sialis
- Sialia currucoides
- Sialia mexicana
- Sialia mexicana occidentalis
- Sialia sialis
- Siamese Fireback
- Siamese Partridge
- Siao Pitta
- Siara Tanager
- Siau Scops-Owl
- Siau Scops Owl
- Siberia
- Siberian Accentor
- Siberian Blue Robin
- Siberian Bush-Warbler
- Siberian Bush Warbler
- Siberian Chiffchaff
- Siberian Crane
- Siberian Flycatcher
- Siberian Ground-Thrush
- Siberian Ground Thrush
- Siberian Grouse
- Siberian Jay
- Siberian Meadow Bunting
- Siberian Nuthatch
- Siberian Rubythroat
- Siberian Stonechat
- Siberian Thrush
- Siberian Tit
- Siberian White Crane
- Sibia
- Sibilant Sirystes
- Sibirionetta
- Sibirionetta formosa
- Sicalis
- Sicalis auriventris
- Sicalis citrina
- Sicalis columbiana
- Sicalis flaveola
- Sicalis flaveola flaveola
- Sicalis lebruni
- Sicalis lutea
- Sicalis luteiventris
- Sicalis luteocephala
- Sicalis luteola
- Sicalis mendozae
- Sicalis olivascens
- Sicalis raimondii
- Sicalis taczanowskii
- Sicalis uropigyalis
- Sicalis uropygialis
- Sichuan Bush Warbler
- Sichuan Gray Jay
- Sichuan Grey Jay
- Sichuan Jay
- Sichuan Leaf-Warbler
- Sichuan Leaf Warbler
- Sichuan Liocichla
- Sichuan Partridge
- Sichuan Thrush
- Sichuan Tit
- Sichuan Treecreeper
- Sichuan Wood-Owl
- Sichuan Wood Owl
- Sicilian Rock Partridge
- Sicily
- Sick's Pygmy Owl
- Sick's Swift
- Sickle-billed Scimitar-Babbler
- Sickle-billed Scimitar Babbler
- Sickle-billed Vanga
- Sickle-crested Bird-of-paradise
- Sickle-crested Bird of Paradise
- Sickle-winged Chat
- Sickle-winged Guan
- Sickle-winged Nightjar
- Sickle Winged Guan
- Sicklebill
- Sicklewing Chat
- Sidamo Lark
- Sidi Bou Ghaba Reserve
- Sidi Bou Ghaba reserve (Ramsar Site)
- Siemianowka Reservoir
- Siemianowka Reservoir Poland
- Sierra Leone
- Sierra Leone Prinia
- Sierra Madre Ground Warbler
- Sierra Madre Sparrow
- Sierra Nevada Brush-Finch
- Sierra Nevada Brush Finch
- Sierra Nevada Brushfinch
- Sierra de Gredos
- Sierra de Gredos Spain
- Sierra de Guadarrama
- Sierra de Guadarrama Spain
- Sierran Elaenia
- Siffling Cisticola
- Sigelus
- Sigelus silens
- Sikkim Treecreeper
- Sikkim Wedge-billed Babbler
- Sikkim Wedge-billed Wren-Babbler
- Sikkim Wedge-billed Wren Babbler
- Silent Cisticola
- Silent Valley LNR
- Silken Satinbird
- Silktail
- Silky-tailed Nightjar
- Silky Crow
- Silky Starling
- Sillem's Mountain Finch
- Sillem's Rosefinch
- Silver-backed Butcherbird
- Silver-backed Needletail
- Silver-backed Tanager
- Silver-beaked Tanager
- Silver-breasted Broadbill
- Silver-breasted Tanager
- Silver-capped Fruit-Dove
- Silver-capped Fruit Dove
- Silver-crowned Friarbird
- Silver-ear
- Silver-eared Honeyeater
- Silver-eared Laughingthrush
- Silver-eared Leiothrix
- Silver-eared Mesia
- Silver-eye
- Silver-faced Tit
- Silver-gray Fulmar
- Silver-grey Fulmar
- Silver-rumped Needletail
- Silver-rumped Spinetail
- Silver-rumped Spinetail Swift
- Silver-spangled Honeyeater
- Silver-throated Bushtit
- Silver-throated Tanager
- Silver-throated Tit
- Silver-tipped Imperial-Pigeon
- Silver-tipped Imperial Pigeon
- Silver Gull
- Silver Honeyeater
- Silver Oriole
- Silver Pheasant
- Silver Teal
- Silverbird
- Silvered Antbird
- Silvereye
- Silvery-cheeked Antshrike
- Silvery-cheeked Hornbill
- Silvery-flanked Antwren
- Silvery-fronted Tapaculo
- Silvery-throated Jay
- Silvery-throated Spinetail
- Silvery Grebe
- Silvery Kingfisher
- Silvery Pigeon
- Silvery Tanager
- Silvery Wood-Pigeon
- Silvery Wood Pigeon
- Silvicultrix diadema
- Silvicultrix frontalis
- Silvicultrix jelskii
- Silvicultrix pulchella
- Silvicultrix spodionota
- Sime Track(MacRitchie Reservoir)
- Simeulue Scops-Owl
- Simeulue Scops Owl
- Simoxenops
- Simoxenops striatus
- Simoxenops ucayalae
- Simple Greenbul
- Sinai
- Sinai Rosefinch
- Sinaloa
- Sinaloa Crow
- Sinaloa Martin
- Sinaloa Wren
- Sincora Antwren
- Sind Babbler
- Sind Jungle Sparrow
- Sind Pied Woodpecker
- Sind Sparrow
- Sind Woodpecker
- Singalila National Park(West Bengal, east India)
- Singalila National Park (West Bengal)
- Singapore
- Singe-wattled Cassowary
- Singing Bush Lark
- Singing Bushlark
- Singing Cisticola
- Singing Honeyeater
- Singing Lark
- Singing Parrot
- Singing Peltops
- Singing Peltops-Flycatcher
- Singing Quail
- Singing Shieldbill
- Singing Starling
- Sinharaja
- Sinharaja Biosphere Reserve
- Sinharaja Forest
- Sinharaja Forest Reserve
- Sinharaja Rainforest
- Sinkiang
- Sinkiang Ground-Jay
- Sinkiang Ground Jay
- Sinosuthora
- Sinosuthora alphonsiana
- Sinosuthora brunnea
- Sinosuthora conspicillata
- Sinosuthora przewalskii
- Sinosuthora webbiana
- Sinosuthora zappeyi
- Sinu Parakeet
- Siphonorhis
- Siphonorhis americana
- Siphonorhis americanus
- Siphonorhis brewsteri
- Sipia
- Sipia berlepschi
- Sipia laemosticta
- Sipia nigricauda
- Sipia palliata
- Sipodotus
- Sipodotus wallacii
- Sipora Scops-Owl
- Sipora Scops Owl
- Siptornis
- Siptornis striaticollis
- Siptornopsis hypochondriacus
- Sira Barbet
- Sira Curassow
- Sira Tanager
- Sirkeer
- Sirkeer Cuckoo
- Sirkeer Malkoha
- Sirystes
- Sirystes albocinereus
- Sirystes albogriseus
- Sirystes sibilator
- Sirystes subcanescens
- Sisserou
- Sitta
- Sitta arctica
- Sitta azurea
- Sitta canadensis
- Sitta carolinensis
- Sitta cashmirensis
- Sitta castanea
- Sitta cinnamoventris
- Sitta europaea
- Sitta europaea amurensis
- Sitta europaea clara
- Sitta formosa
- Sitta frontalis
- Sitta frontalis frontalis
- Sitta himalayensis
- Sitta krueperi
- Sitta ledanti
- Sitta leucopsis
- Sitta magna
- Sitta nagaensis
- Sitta neglecta
- Sitta neumayer
- Sitta oenochlamys
- Sitta oenochlamys isarog
- Sitta przewalskii
- Sitta pusilla
- Sitta pygmaea


