- La Sagra's Flycatcher
- La Selle Thrush
- Laced Woodpecker
- Lacrimose Mountain Tanager
- Ladder-backed Woodpecker
- Lafresnaye's Vanga
- Lanceolated Warbler
- Lapland Longspur
- Large-billed Antwren
- Large-billed Crow
- Large-billed Tern
- Large-footed Finch
- Large-tailed Antshrike
- Large Ground Finch
- Large Hawk-Cuckoo
- Large Niltava
- Lark-like Brushrunner
- Lark Sparrow
- Laughing Dove
- Laughing Falcon
- Laughing Gull
- Lava Gull
- Lava Heron
- Lazuli Bunting
- Least Auklet
- Least Bittern
- Least Flycatcher
- Least Grebe
- Least Sandpiper
- Least Seedsnipe
- Least Tern
- LeConte's Thrasher
- Lemon-bellied Flyrobin
- Lemon-browed Flycatcher
- Lemon-rumped Tanager
- Lemon-rumped Warbler
- Lesser Antillean Bullfinch
- Lesser Antillean Flycatcher
- Lesser Antillean Pewee
- Lesser Antillean Saltator
- Lesser Antillean Swift
- Lesser Antillean Tanager
- Lesser Goldfinch
- Lesser Kiskadee
- Lesser Necklaced Laughingthrush
- Lesser Nighthawk
- Lesser Racket-tailed Drongo
- Lesser Rhea
- Lesser Roadrunner
- Lesser Scaup
- Lesser Swamp Warbler
- Lesser Woodcreeper
- Lesser Yellow-headed Vulture
- Lesser Yellowlegs
- Lettered Aracari
- Levaillant's Cisticola
- Light-mantled Albatross
- Light-vented Bulbul
- Lilac-breasted Roller
- Limpkin
- Lincoln's Sparrow
- Line-cheeked Spinetail
- Lineated Foliage-gleaner
- Lineated Woodpecker
- Lined Forest Falcon
- Little Blue Heron
- Little Bunting
- Little Chachalaca
- Little Cuckoo-Dove
- Little Grebe
- Little Green Pigeon
- Little Hermit
- Little Ringed Plover
- Little Rush Warbler
- Little Spiderhunter
- Little Swift
- Little Tern
- Little Woodpecker
- Lizard Buzzard
- Loggerhead Kingbird
- Loggerhead Shrike
- Loja Tyrannulet
- Long-billed Bernieria
- Long-billed Cuckoo
- Long-billed Curlew
- Long-billed Dowitcher
- Long-billed Hermit
- Long-billed Murrelet
- Long-billed Plover
- Long-billed Starthroat
- Long-billed Wren
- Long-tailed Broadbill
- Long-tailed Duck
- Long-tailed Ground Dove
- Long-tailed Ground Roller
- Long-tailed Hermit
- Long-tailed Honey Buzzard
- Long-tailed Manakin
- Long-tailed Meadowlark
- Long-tailed Minivet
- Long-tailed Mockingbird
- Long-tailed Myna
- Long-tailed Shrike
- Long-tailed Sibia
- Long-tailed Silky-flycatcher
- Long-tailed Sylph
- Long-tailed Tit
- Long-tailed Tyrant
- Long-toed Stint
- Long-wattled Umbrellabird
- Long-winged Antwren
- Long-winged Harrier
- Louisiana Waterthrush
- Lowland Peltops
- Luzon Water Redstart