- Sabine's Gull
- Saffron Finch
- Sand Martin
- Sanderling
- Sandhill Crane
- Sandwich Tern
- Savannah Sparrow
- Say's Phoebe
- Scaled Quail
- Scarlet-rumped Cacique
- Scarlet Flycatcher
- Scarlet Tanager
- Scissor-tailed Flycatcher
- Semipalmated Plover
- Semipalmated Sandpiper
- Shiny Cowbird
- Short-billed Dowitcher
- Short-eared Owl
- Slaty-tailed Trogon
- Smooth-billed Ani
- Snail Kite
- Snow Bunting
- Snow Goose
- Snowy-bellied Hummingbird
- Snowy Egret
- Snowy Plover
- Social Flycatcher
- Solitary Sandpiper
- Song Sparrow
- Sora
- Southern Beardless Tyrannulet
- Southern Lapwing
- Spot-breasted Oriole
- Spotted Sandpiper
- Spotted Towhee
- Squirrel Cuckoo
- Steller's Jay
- Stilt Sandpiper
- Streak-backed Oriole
- Striated Heron
- Strickland's Woodpecker
- Summer Tanager
- Swainson's Hawk
- Swainson's Thrush
- Swamp Sparrow