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Birdaday Field Notes

Glossary

Birding glossary: birder terms and abbreviations from A to Z

A lifer is a species you see for the first time, FOY means "first of year," a nemesis bird is one you keep failing to find, and a four-letter alpha code such as NOCA is shorthand for a species name, here Northern Cardinal. This glossary defines the terms and abbreviations US birders meet most, from the listing words of the American Birding Association (ABA) to the checklist options in eBird, each defined from an official or published source. For the names of a bird's body parts (wing bars, supercilium, coverts), see parts of a bird.

Birding abbreviations chart

The abbreviations below turn up in eBird, count results, field notes and rare-bird reports.

Abbreviation Stands for What it means
ABA American Birding Association Keeps the ABA Checklist of species for the ABA Area and its Codes 1–6
AOS American Ornithological Society Sets the English bird names that ABA Checklist alpha codes follow
BBL (US) Bird Banding Laboratory Has long used four-letter alpha codes in banding data
IBP The Institute for Bird Populations Maintains the current four- and six-letter alpha code lists, updated each year
NOCA, BCCH… Northern Cardinal, Black-capped Chickadee… Four-letter alpha codes for species names (see the figure)
CBC Christmas Bird Count Audubon's count held each year from December 14 to January 5, running since 1900
GBBC Great Backyard Bird Count A four-day count held in February; watch birds for at least 15 minutes
FOY First of year Your first sighting of a species in a calendar year
FOS First of season A species seen again in a later season, such as a fall return after a spring sighting
LBJ Little brown job A plain, drab songbird that is hard to tell from similar ones
ISSF Identifiable Sub-specific Group eBird entry for a subspecies or group of subspecies you can tell apart
sp. ("spuh") species eBird entry for a bird named only to a broad group, such as "swan sp."
X (present) eBird entry for a species you identified but did not count
NFC Nocturnal Flight Call eBird protocol for listening at night for migrating songbirds
How a four-letter bird alpha code is formed from the English nameFive rows. Row 1: Mallard, a one-word name, gives MALL from its first four letters. Row 2: Northern Cardinal, two words, gives NOCA from the first two letters of each word. Row 3: Black-capped Chickadee, a hyphenated three-part name, gives BCCH from the first letter of Black and of capped plus the first two letters of Chickadee. Row 4: Black-crowned Night Heron, four parts, gives BCNH from the first letter of each part. Row 5: American Goldfinch would give AMGO under the two-word rule, but the IBP list gives AGOL, marked with an asterisk as a code changed because of a conflict. From English name to alpha code 1 Mallard 2 Northern Cardinal 3 Black-capped Chickadee 4 Black-crowned Night Heron 5 American Goldfinch one word: first four letters two words: first two of each three parts: 1 + 1 + first two four parts: first letter of each conflict: rule gives AMGO, list gives AGOL* MALLNOCABCCHBCNHAGOL* Codes as listed by The Institute for Bird Populations (2025 list).
  1. One-word name: the first four letters. Mallard is MALL.
  2. Two-word name: the first two letters of each word. Northern Cardinal is NOCA.
  3. Hyphenated three-part name: the first letter of each hyphenated part plus the first two letters of the last word. Black-capped Chickadee is BCCH.
  4. Four parts: the first letter of each. Black-crowned Night Heron is BCNH.
  5. Conflicts: no two species may share a code, so some codes are set case by case. The two-word rule would make American Goldfinch AMGO; the IBP list gives AGOL, with an asterisk marking a code that is not "1st-order" because of a conflict.
Drawn for Birdaday Field Notes from the formation rules in Manomet's 2026 beginner's guide to alpha codes and Wikipedia's "Bird codes" article, with every code checked against The Institute for Bird Populations' 2025 alpha code list (all under Sources).

Where code lists differ. The BBL and the IBP do not always agree. Under the basic rules, Canada Goose and Cackling Goose would both be CAGO. The BBL kept CAGO for the more common Canada Goose and gave Cackling Goose CACG; the IBP gives neither bird CAGO and uses CANG and CACG. The IBP says its codes "broadly follow" BBL rules but also cover species of Mexico, Central America and the Caribbean that the BBL list leaves out.

A

ABA Area
The region the ABA Checklist covers: "essentially North America north of Mexico plus the Hawaiian Islands." The checklist (version 8.19, January 2026) lists 1,161 species.
ABA code
A number from 1 to 6 on the ABA Checklist that says how regularly a species occurs in the ABA Area, from regular (Code 1) to cannot be found (Code 6). Not the same as an alpha code; see ABA codes explained.
Alpha code also banding code
An abbreviation of a bird name: four letters from the English name (NOCA) or six from the scientific name (POEATR for Black-capped Chickadee on the IBP list). The US Bird Banding Laboratory has long used them in banding data; the IBP now maintains lists updated each year after the AOS checklist supplement. On the ABA Checklist, the four-letter codes follow the AOS English names.

B

Big Year
A one-year species list kept under set rules. Under the ABA's rules, an ABA Area Big Year runs from 12:00 AM January 1 to 11:59 PM December 31, local time, and each species must be on the ABA Checklist. See Big Year explained.
Bird-a-Day
A challenge in which you find a new species each day and see how many days in a row you can keep going. Audubon notes there is no "bird-a-day police," so players set their own rules. See the challenge guide.

C

Checklist (eBird)
One eBird list of the birds you found. Each checklist must cover a single calendar date, a single map location, and one observation type, or protocol.
Complete checklist
A checklist on which "every species you could identify to the best of your ability, by sight and/or sound, is reported." Leaving out introduced species or heard-only birds you identified makes it incomplete. Unknown birds can go in as a spuh or slash.
Countable
A bird that meets the five ABA Recording Rules (version 2020): within the area and time period, a species on the ABA Checklist, "alive, wild, and unrestrained," identified by diagnostic marks seen and/or heard, and encountered in line with the ABA Code of Birding Ethics. A bird identified by sound alone can count.

D

Dip, dipped
To miss a bird you went looking for (Audubon).
Domestic
An eBird category for distinctly plumaged domesticated varieties, such as "Mallard (Domestic type)," that may be free-flying. These do not count on personal lists.

E

Endemic
A species found only in one small, isolated area (Audubon).
Escapee
An eBird label for a bird that escaped from captivity. Species marked as escapees do not count toward your personal species totals, and suspected escaped, exotic or domestic birds may be marked Rare so they are not mistaken for wild ones in public data.

F

FOY first of year
Your first sighting of a species in a calendar year. When the same species returns in a later season, for example in October after an April sighting, some birders log it as FOS, first of season (Hitchcock Center for the Environment). NH Audubon uses FOY for something as ordinary as the year's first American Crow.

H

Historical (eBird)
The checklist type for birding when you know the date but not the exact start time, duration or distance.
Hotspot
A public eBird birding location, suggested by users and approved by a volunteer Hotspot Admin, that everyone can choose and whose sightings are combined. A personal location is visible only to you and the people you share the list with.
Hybrid
In eBird, a bird that is a cross between two species, entered as, for example, "Tundra x Trumpeter Swan (hybrid)." An intergrade is the same between two subspecies groups.

I

Incidental (eBird)
The checklist type for when birding was not your main focus: a hawk seen from the car, birds noticed while gardening. Incidental lists are not complete.
ISSF
"Identifiable Sub-specific Group": an eBird entry for a subspecies or group you can tell apart, such as "Tundra Swan (Bewick's)."

L

LBJ little brown job
A catchall for plain, drab songbirds that are hard to tell apart (Audubon). For one hard group, see the sparrow ID guide.
Life list
Every species you have ever recorded. eBird defines your Life List as "the total number of species that you've ever reported to eBird," and can show it for any region from county to worldwide.
Lifer
A bird you see for the first time (Audubon): a new species for your life list.

N

Nemesis bird
A species you repeatedly fail to find (Audubon).

P

Patch, yard list
In eBird, a patch is "a series of locations, generally referring to the same area," small enough to bird in a morning or a few hours; your yard list is the patch where you live, which should be limited to property you own or rent. eBird totals each patch's life, year and month species.
Patagonia Picnic Table Effect
When one rare bird draws so many birders to a spot that they find other unusual birds nearby (Audubon).
Pelagic
Describes birds that spend most of their lives on the open ocean (Audubon). eBird's Pelagic protocol is for checklists made more than two miles offshore.
Pish
A sound birders make to coax songbirds into view (Audubon).

S

Slash
An eBird entry for a bird narrowed to two species, such as "Tundra/Trumpeter Swan."
Spark bird
The species that sparked your interest in birds (Audubon).
Spuh sp.
An eBird entry for a bird identified only to genus or a broad group, such as "swan sp." eBird calls these entries "spuhs."
Stationary (eBird)
The checklist type for birding at one fixed spot, staying within about 30 m (100 ft) of where you started.

T

Traveling (eBird)
The checklist type for birding when you moved more than 30 m (100 ft) from the start; you enter the distance covered. See eBird for beginners.
Twitcher
A dedicated birder who travels far to see a species and add it to a list (Audubon). Making such a trip is "twitching," also called chasing (Wikipedia).

V

Vagrant
A bird found well outside its normal range (Audubon). For how the ABA rates such records, see ABA codes explained.

X

X
What you enter in eBird for a species you identified but did not count. eBird asks for a count or estimate instead where possible, because an X "only tells us the species was present - but there could be anywhere from 1 to 1,000,000!"

Y

Year list
The species you record in one calendar year, the list a Big Year is built on and a FOY adds to. eBird shows current-year totals in My eBird and on each patch or yard page; the year in review explains how to pull yours.

Sources