- Cabot's Tern (eurygnathus)
- Calandra Lark
- Campo Flicker
- Canada Goose
- Canada Jay
- Canada Warbler
- Canary Islands Chiffchaff
- Canary Islands Stonechat
- Cape Cormorant
- Cape Crow
- Cape Gannet
- Cape Longclaw
- Cape Robin-Chat
- Cape Rock Thrush
- Cape Shoveler
- Cape Sparrow
- Cape Starling
- Cape Vulture
- Cape Wagtail
- Cape Weaver
- Cape White-eye
- Carrion Crow
- Caspian Gull
- Caspian Plover
- Caspian Tern
- Cattle Tyrant
- Cedar Waxwing
- Cetti's Warbler
- Chaco Chachalaca
- Chalk-browed Mockingbird
- Chestnut-backed Sparrow-Lark
- Chestnut-capped Blackbird
- Chestnut-sided Warbler
- Chestnut-vented Conebill
- Chiguanco Thrush
- Chilean Flamingo
- Chilean Swallow
- Chiloe Wigeon
- Chimango Caracara
- Chimney Swift
- Chinspot Batis
- Chipping Sparrow
- Chorister Robin-Chat
- Chukar Partridge
- Cinereous Bunting
- Cinereous Ground Tyrant
- Cinereous Harrier
- Cinereous Tit
- Cinereous Vulture
- Cinnamon Teal
- Cinnamon Warbling Finch
- Cirl Bunting
- Citril Finch
- Citrine Wagtail
- Citron-headed Yellow Finch
- Cliff Flycatcher (bellicosa)
- Coal Tit
- Cobalt-rumped Parrotlet
- Cockatiel
- Cocoi Heron
- Collared Flycatcher
- Collared Pratincole
- Collared Scops Owl
- Collared Sunbird
- Common Babbler
- Common Blackbird
- Common Bulbul
- Common Buzzard
- Common Chiffchaff
- Common Chiffchaff (tristis)
- Common Chlorospingus
- Common Crane
- Common Cuckoo
- Common Eider
- Common Firecrest
- Common Goldeneye
- Common Grackle
- Common Grasshopper Warbler
- Common Greenshank
- Common Gull
- Common Iora
- Common Kestrel
- Common Kingfisher
- Common Linnet
- Common Loon
- Common Merganser
- Common Moorhen
- Common Murre
- Common Myna
- Common Nighthawk
- Common Nightingale
- Common Ostrich
- Common Pheasant
- Common Pochard
- Common Quail
- Common Redpoll
- Common Redshank
- Common Redstart
- Common Reed Bunting
- Common Reed Warbler
- Common Reed Warbler (baeticatus)
- Common Ringed Plover
- Common Rock Thrush
- Common Rosefinch
- Common Sandpiper
- Common Scimitarbill
- Common Scoter
- Common Shelduck
- Common Snipe
- Common Starling
- Common Swift
- Common Tailorbird
- Common Tern
- Common Waxbill
- Common Whitethroat
- Common Wood Pigeon
- Common Woodshrike
- Common Yellowthroat
- Coppersmith Barbet
- Coqui Francolin
- Corn Bunting
- Corsican Finch
- Corsican Nuthatch
- Cory's Shearwater
- Coscoroba Swan
- Crane Hawk
- Cream-backed Woodpecker
- Cream-colored Courser
- Creamy-bellied Thrush
- Crested Barbet
- Crested Caracara
- Crested Duck
- Crested Francolin
- Crested Lark
- Crested Myna
- Crested Oropendola
- Crested Serpent Eagle
- Crested Tit
- Cretzschmar's Bunting
- Croaking Cisticola
- Crowned Hornbill
- Crowned Lapwing
- Curlew Sandpiper
- Cut-throat Finch
- Cyprus Warbler
- Cyprus Wheatear