- Mackinnon's Shrike
- Magellanic Penguin
- Magenta-throated Woodstar
- Magnificent Frigatebird
- Magpie Tanager
- Malabar Pied Hornbill
- Malabar Trogon
- Malachite Kingfisher
- Malachite Sunbird
- Malagasy Turtle Dove
- Mallard
- Mandarin Duck
- Mangrove Cuckoo
- Mangrove Swallow
- Mangrove Warbler
- Manx Shearwater
- Many-banded Aracari
- Many-colored Rush Tyrant
- Many-spotted Hummingbird
- Many-striped Canastero
- Marabou Stork
- Marble-faced Bristle Tyrant
- Marbled Duck
- Marico Flycatcher
- Marico Sunbird
- Maroon-tailed Parakeet
- Marsh Sandpiper
- Marsh Tchagra
- Marsh Tit
- Marsh Warbler
- Martial Eagle
- Martinique Oriole
- Mascarene Martin
- Masked Crimson Tanager
- Masked Flowerpiercer
- Masked Gnatcatcher
- Masked Tityra
- Masked Trogon
- Masked Water Tyrant
- Meadow Pipit
- Mealy Amazon
- Mediterranean Gull
- Mediterranean Short-toed Lark
- Melodious Blackbird
- Melodious Warbler
- Mexican Violetear
- Meyer's Parrot
- Mistle Thrush
- Mistletoe Tyrannulet
- Monk Parakeet
- Montagu's Harrier
- Montane Woodcreeper
- Monteiro's Hornbill
- Montezuma Oropendola
- Morelet's Seedeater
- Mosque Swallow
- Mottled Owl
- Mountain Bluebird
- Mountain Caracara
- Mountain Elaenia
- Mountain Wagtail
- Mountain Wheatear
- Mountain Wren
- Mourning Collared Dove
- Mourning Sierra Finch
- Moustached Antpitta
- Moustached Grass Warbler
- Moustached Warbler
- Muscovy Duck
- Mute Swan