- Magnificent Frigatebird
- Magpie Shrike
- Magpie Tanager
- Mallard
- Mangrove Warbler
- Manx Shearwater
- Many-spotted Hummingbird
- Many-striped Canastero
- Marabou Stork
- Marail Guan
- Maranon Spinetail
- Maranon Thrush
- Marico Flycatcher
- Marico Sunbird
- Marsh Tit
- Martial Eagle
- Masked Duck
- Masked Flowerpiercer
- Masked Tityra
- Masked Trogon
- Masked Water Tyrant
- Masked Yellowthroat
- McConnell's Flycatcher
- McConnell's Spinetail
- Meadow Pipit
- Melodious Warbler
- Meves's Starling
- Mistle Thrush
- Monteiro's Hornbill
- Mottle-backed Elaenia
- Mottled Owl
- Mountain Caracara
- Mountain Wheatear
- Mouse-colored Antshrike
- Mouse-colored Thistletail
- Mouse-colored Tyrannulet
- Muscovy Duck
- Musician Wren
- Mute Swan