- Madeira Firecrest
- Magellanic Penguin
- Magnolia Warbler
- Magpie Tanager
- Maguari Stork
- Mallard
- Mandarin Duck
- Mangrove Swallow
- Mangrove Warbler
- Manx Shearwater
- Many-banded Aracari
- Many-colored Rush Tyrant
- Many-spotted Hummingbird
- Marble-faced Bristle Tyrant
- Marbled Godwit
- Marcapata Spinetail
- Marsh Tit
- Marvelous Spatuletail
- Masked Booby
- Masked Crimson Tanager
- Masked Flowerpiercer
- Masked Fruiteater
- Masked Gnatcatcher
- Masked Shrike
- Masked Tityra
- Masked Trogon
- Meadow Pipit
- Mediterranean Gull
- Medium Ground Finch
- Melodious Blackbird
- Melodious Warbler
- Merlin
- Mew Gull
- Mexican Violetear
- Middle Spotted Woodpecker
- Mistle Thrush
- Mitred Parakeet
- Monk Parakeet
- Montagu's Harrier
- Montane Foliage-gleaner
- Montane Woodcreeper
- Montezuma Oropendola
- Mountain Caracara
- Mountain Parakeet
- Mountain Thrush
- Mountain Trogon
- Mountain Velvetbreast
- Mountain Wren
- Mourning Sierra Finch
- Mourning Warbler
- Mouse-colored Tyrannulet
- Moustached Flowerpiercer
- Mute Swan