- Saffron-crowned Tanager
- Saffron Finch
- Sanderling
- Sandhill Crane
- Santa Marta Brushfinch
- Santa Marta Woodstar
- Sapphire-throated Hummingbird
- Savanna Hawk
- Savannah Sparrow
- Scaled Dove
- Scaly-breasted Hummingbird
- Scarlet-bellied Mountain Tanager
- Scarlet-rumped Cacique
- Scarlet-rumped Tanager
- Scarlet-rumped Tanager (costaricensis)
- Scarlet Ibis
- Scarlet Macaw
- Scarlet Tanager
- Scintillant Hummingbird
- Scissor-tailed Flycatcher
- Scrub Euphonia
- Scrub Tanager
- Sedge Wren
- Semipalmated Plover
- Semipalmated Sandpiper
- Sharp-shinned Hawk
- Shining Honeycreeper
- Shining Sunbeam
- Shiny Cowbird
- Short-billed Dowitcher
- Short-billed Pigeon
- Short-eared Owl
- Sickle-winged Guan
- Silver-throated Tanager
- Slate-throated Whitestart
- Slaty-backed Chat-Tyrant
- Slaty-crowned Antpitta
- Slaty-headed Tody-Flycatcher
- Slaty-tailed Trogon
- Slaty Brushfinch
- Slaty Flowerpiercer
- Slender-billed Inezia
- Smooth-billed Ani
- Snail Kite
- Snow Bunting
- Snow Goose
- Snowy-bellied Hummingbird
- Snowy Egret
- Snowy Owl
- Snowy Plover
- Social Flycatcher
- Solitary Sandpiper
- Song Sparrow
- Song Wren
- Sooty-capped Chlorospingus
- Sooty Thrush
- Sora
- Southern Lapwing
- Southern Tropical Pewee
- Sparkling Violetear
- Speckled Hummingbird
- Speckled Tanager
- Spectacled Owl
- Spectacled Parrotlet
- Spot-breasted Oriole
- Spot-crowned Euphonia
- Spot-crowned Woodcreeper
- Spotted Antbird
- Spotted Sandpiper
- Squirrel Cuckoo
- Steely-vented Hummingbird
- Stilt Sandpiper
- Stolid Flycatcher
- Stout-billed Cinclodes
- Streak-backed Oriole
- Streak-chested Antpitta
- Streak-headed Woodcreeper
- Streak-throated Bush Tyrant
- Streaked Flycatcher
- Stripe-backed Wren
- Stripe-headed Sparrow
- Stripe-tailed Hummingbird
- Striped Owl
- Sulphur-winged Parakeet
- Summer Tanager
- Sungrebe
- Surfbird
- Swainson's Hawk
- Swainson's Thrush
- Swallow-tailed Kite
- Swamp Sparrow
- Sword-billed Hummingbird