Bird BiosAlpha Codes for Cavity Nesters

Alpha Codes for Cavity Nesters

Just a few ALPHA CODES FOR CAVITY NESTING BIRDS that may use nestboxes. A full list of alpha codes is available here. Another more complete list of 4 letter codes (for English common names) and 6 letter codes (for scientific names) is found at The Institute for Bird Populations.

Commonly used alpha codes for birds names have four letters. Generally, the rule for alpha codes for two word bird names is the first two letters of the first word followed by the first two letters of the second word – thus Eastern Bluebird = EABL, and PUrple MArtin = PUMA. See neat online bird identification guide.

Note that my list is NOT authoritative! Different groups/individuals may use different lists of cavity nesters. It gets complicated for a variety of reasons:

  • how species are divided (some may list subspecies or use different taxonomic classifications) or lumped together (e.g., introduced varieties of lovebirds, parrots and parakeets)
  • how they define cavity (e.g., does it include a hole in a cliff or a chimney?), whether they ALWAYS, sometimes or occasionally use a cavity
  • whether to count non-native (introduced) species like parrots
  • whether to count parasitic birds (like cowbirds which don’t build their own nest but will lay an egg in another bird’s nest)
  • what geographic area is covered (e.g., United States/North America)
  • how current the list is (e.g., old lists may not have noted that Red-cockaded Woodpeckers will use a nestbox; new non-natives are being introduced)
  • whether the list is evidence based (n confirmed reports/research)

Also see acronyms list and glossary.


  • When there are more than one species of bird with the same letters, they use the first 3 letters of the first word and the first letter only of the second word – thus TRUmpeter Swan = TRUS and Tree Swallow = TRES.
  • Four word bird names use the first letter of first word, first letter of second word, and first two letters of third word. Another exception when all four words have same initials: BTNW = Black-throated Green Warbler, BTYW = Black-throated Gray Warbler.
  • Subspecies: ETTI refers to the subspecies Eastern Tufted Titmouse. You really need to have the bird in hand to get to subspecies. If you just hear the titmouse in the tree or see it at the feeder, it’s a TUTI, a regular Tufted Titmouse. If you just hear a flicker, it’s a NOFL, a Northern Flicker. If you can see the color on the wings, you can call it a Red- or Yellow-shafted Flicker, RSFL or YSFL.

Click on the alpha code for more info on biology, nesting behavior, nestboxes, etc.

(An asterisk [*] indicates they may use a NESTBOX) Not all bird names and codes may be up to date. (Some are not listed on as using nestboxes)
EABL = Eastern Bluebird *
MOBL = Mountain Bluebird *
WEBL = Western Bluebird ****ACWO = Acorn Woodpecker
AMKE = American Kestrel *
ATFL = Ash-throated Flycatcher *
BADO = Barred Owl
BANO = Barn Owl – also BNOW *
BCCH = Black-capped Chickadee *
BBWD = Black-bellied Whistling Duck *
BCTI = Black-crested titmouse (TX and Mexico) * (not listed on
BEWR = Bewick’s wren *
BHCO = Brown-headed cowbird (nest parasite – does not build it’s own nest, not listed on
BEWR = Bewick’s wren *
BHNU = Brown-headed Nuthatch *
BNOW = Barn Owl
– also BANO *
BOCH = Boreal Chickadee *
BUFF = Bufflehead *
BRTI = Bridled titmouse
BROC = Bronzed Cowbird (nest parasite,
not listed on
CACH = Carolina Chickadee *
CARW = Carolina Wren *
CBCH = Chestnut-backed Chickadee *
CHSW = Chimney Swift (nests in chimneys, not listed on
COGO = Common Goldeneye *
COME = Common Merganser
DOWO = Downy Woodpecker * (roosting)
EASO = Eastern Screech Owl *
EUST = European Starling * (not listed on
ETSP = Eurasian Tree Sparrow * (not listed on
ETTI= see TUTI or BCTI – the ETTI code is no longer in use *
FLOW = Flammulated Owl (not listed on
= Great Crested Flycatcher *
GIFL = Gilded Flicker (not listed on
GRCH = Gray-headed Chickadee
(not listed on

HAWO = Hairy Woodpecker * (not listed on
HOME = Hooded Merganser *
HOSP = House Sparrow * (not listed on
HOWR = House Wren *
JUTI = Juniper Titmouse (formerly with Oak Titmouse as Plain Titmouse)
LEWO = Lewis’s Woodpecker (not listed on *
LUWA = Lucy’s Warbler
MECH = Mexican Chickadee (not listed on
MOCH = Mountain Chickadee *
NOFL = Northern Flicker *
OATI = Oak Titmouse (formerly with Juniper Titmouse as Plain Titmouse) *
PIWO = Pileated Woodpecker
PROW = Prothonotary Warbler *
PUMA = Purple Martin *
PYNU = Pygmy Nuthatch *
RBNU = Red-breasted Nuthatch *
RBWO = Red-bellied Woodpecker (not listed on
RCWO = Red-cockaded Woodpecker (not listed on
RHWO = Red-headed Woodpecker (not listed on
SHCO = Shiny Cowbird
TRES = Tree Swallow *
TUTI = Tufted Titmouse. (Previously referred to as Eastern Tufted Titmouse or ETTI *)
VGSW = Violet-green Swallow *
WBNU = White-breasted Nuthatch *
WESO = Western Screech Owl *
WODU = Wood Duck *

Lilac-crowned Parakeet
Monk Parakeet/Quaker Parrot
Orange-winged Parrot
Rosy-faced Lovebird
White winged Parakeet
Yellow-headed Parrot

Other North American Birds that reportedly MAY nest in cavities

Barrow’s Goldeneye
Black-backed Woodpecker
Black Vulture
Boreal Owl*
Brown-crested Flycatcher *
Burrowing Owl (nests in ground)
California Condor
Canary-winged Parakeet
Cliff Swallow (nests in holes in cliffs)
Common Grackle
Crested Myna
Ducky-capped Flycatcher
Eared Trogon
Cordilleran Flycatcher
Elegant Trogon
Elf Owl
Ferruginous Pygmy-Owl
Fulvous Whistling-Duck
Gila Woodpecker
Great Gray Owl
Great Horned Owl
Golden-Fronted Woodpecker*
Ivory-billed Woodpecker
Ladder-backed Woodpecker
Lucy’s Warbler
Muscovy Duck*
Northern Hawk-Owl
Northern Pygmy Owl
Northern Saw-whet Owl*
Nuttall’s Woodpecker
Pacific-slope Flycatcher
Pileated Woodpecker
Red-breasted Merganser
Red-breasted sapsucker
Say’s Phoebe
Spotted Owl
Strickland’s Woodpecker
Three-toed Woodpecker
Turkey Vulture
Vaux’s Swift
Yellow-bellied Sapsucker
Whiskered Screech Owl
White Wagtail
White-headed Woodpecker
Williamson’s Sapsucker
North American Birds that nest on PLATFORMS (not true cavity nesters in my opinion)
American Robin
Barn Swallow
Eastern Phoebe
Great Blue Heron
Mourning Dove
Say’s Phoebe
Unusual Cases of Birds Nesting in Boxes
According to Nestwatch at Cornell, they have documented a Dark-eyed Junco nesting in a nest box, a Greater Roadrunner using an open-fronted nestbox, and Common Grackles using nestboxes if the entrance hole is large enough!



There is another alphabet, whispering from every leaf, singing from every river, shimmering from every sky.
― Dejan Stojanovic


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