For those of you who use Quick Entry Codes, and want to learn more about how they were created, you're in the right place. This gets into the specifics of how the codes are generated. If you just want a quick version that should have most everything you'll need to know, we recommend checking out the Quick Entry Codes in eBird article.
So, how do we determine the codes?
Bird banders (ringers) long have used four-letter codes to enter data on banded birds. Those who are fluent in these codes will know that COTE refers to Common Tern, PEFA refers to Peregrine Falcon, and DUNL is shorthand for Dunlin. These codes were designed to be unique, and those that are really fluent may even know some of the exceptions: BARS is used for Barn Swallow (due to a conflict with Bank Swallow, less of an issue outside the USA where Riparia riparia is known as Sand Martin) and CEWA is not a legitimate code, since it could refer to Cedar Waxwing (CEDW) or Cerulean Warbler (CERW). In recent years, the official list of codes in North America used by the Bird Banding Laboratory has been maintained by the Institute for Bird Populations here. These “official” four-letter codes are each unique have been available in eBird for a long time and show at the top of search results. Within eBird, we refer to these as “Banding Codes”.
eBird Quick Find Codes
Within eBird, we have also implemented a “quick find” code. These do not need to be unique, and no longer is it necessary to remember the obscure rules for resolving conflicts like Cerulean Warbler and Barn Swallow. Instead, you can simply apply a uniform set of rules to get a quick four-letter code for any bird in the world. Within eBird, we refer to these as “eBird Quick Find Codes”.
The rules for creating eBird Quick Find Codes depend on how many words are in the bird name. Many of these match the Banding Code above, but in some cases eBird Quick Find Code differs. Here are the rules:
One-word bird names: The code is the first four letters of the bird name.
Examples: Gadwall = GADW; Willet = WILL.
Two-word bird names: Use the first two letters of the first word and the first two letters of the second word. Common Tern thus becomes COTE.
Examples: Spotted Redshank = SPRE; House Sparrow = HOSP.
Three-word bird names: Use the first letter of each of the first two words and the first two letters of the last word. South Polar Skua becomes SPSK, Long-tailed Jaeger becomes LTJA, and Eurasian Collared-Dove becomes ECDO (see below discussion on hyphens).
Examples: Red-winged Blackbird = RWBL; Fernando Po Batis = FPBA; Australian Brush-Turkey = ABTU.
*hyphens: Note that many bird names have hyphens. These can be ignored in most cases, but where the last word of the bird name is a compound word connected by a hyphen (e.g., Scops-Owl, Collared-Dove, Brush-Turkey), special rules apply. When the IBP constructs Banding Codes, it uses the first letter from each of those words, so they use Eurasian Collared-Dove (EUCD) instead of ECDO. For our quick find codes, we offer both options, since it can be very hard to remember whether a bird name is hyphenated or not. Many common name language translations (see below) do not use hyphenated compound words as commonly in bird names as well (e.g., IOC English names). Providing both options ensures that most people will easily be able to find the bird name they are seeking.
Four-word bird names: Just use the first letter of each word. Treat hyphens and spaces equally. Thus Black-throated Green Warbler (BTGW), White-winged Black-Tyrant (WWBT), and Von der Decken’s Hornbill (VDDH) are all constructed similarly, despite the different hyphenation.
Examples: Black-throated Magpie-Jay = BTMJ; Black-bellied Storm-Petrel = BBSP
Bird names longer than four words: Sixteen species have five-word bird names. For these names you have two options. First, you can just begin at the beginning of the word and use the first letter of each of the first four words. Black-and-white Casqued Hornbill would thus be BAWC. Also, you can omit the obvious conjunctions and just stick with the capitalized letters of the bird name. Using this option, Black-and-white Casqued Hornbill would be BWCH. There is only one six-word bird name: King-of-Saxony Bird-of-Paradise (KOSB or KSBP).
Alternate common names
eBird offers common name alternatives in many other languages, including customized English name constructions for the Australia, United Kingdom, India, Middle East, Malaysia, New Zealand, and the Philippines. We also offer IOC names matching the IOC World Bird list v4.4. All alternate common names are indexed as an eBird Quick Find Code as well, so for Buteo lagopus you can type RLHA if you know it as Rough-legged Hawk or RLBU if you know it as Rough-legged Buzzard. We don't yet have quick-find codes for non-English languages.
Scientific Names Quick Find Codes
For those that know scientific names, these rules are the easiest to remember since all species-level scientific names are two and exactly two words. Thus, Turdus migratorius (American Robin) can be found by TUMI and BULA will work for Rough-legged Hawk (Buteo lagopus).
Using codes for Non-species
All codes above—Banding Codes, eBird Quick Find Codes for all English names (including translations), and Scientific Name Quick Find Codes—apply to all species. However, the eBird taxonomy also includes non-species (more here). A few North American subspecies groups, hybrids, and slashes (species pairs) have official Banding Codes and these are included. But to find most of these options, just use the code of the parent or component species. Thus, a subspecies would use the code of the parent species, while a hybrid or slash would be indexed by both of the species that make up that “slash”. Examples from each of the categories are below.
Identifiable Sub-specific Forms (ISSFs or “subspecies groups”) – These are indexed by the codes of the parent species. Thus, Lesser Rhea (Darwin’s) Rhea pennata pennata can be found by searching LERH or RHPE, the codes for the common name and scientific name respectively.
Domestics – Graylag Goose (domestic) can be found by entering the codes for Graylag Goose Anser anser: GRGO or ANAN.
Hybrids – Hybrids like Townsend’s x Hermit Warbler (hybrid) Setophaga townsendi x occidentalis can be found by searching for the codes for Townsend’s Warbler (TOWA or SETO) or Hermit Warbler (HEWA or SEOC).
Intergrades – Intergrades are essentially hybrids between subspecies. So Yellow-rumped Warbler (Myrtle x Audubon's) Setophaga coronata coronata x auduboni can be found by searching for the code for the parent species, Yellow-rumped Warbler (YRWA or SECO). In this special case, Yellow-rumped Warbler (Myrtle) also has a Banding Code of MYWA and Yellow-rumped Warbler (Audubon’s) has a banding code of AUWA. Typing either of these codes will also give these ISSFs (subspecies groups) as well as this intergrade as an option, since these are the “parent taxa” for those.
Forms – eBird forms are sort of a catch-all. Some of these are undescribed species, like the San Pedro Tanager (undescribed form) Thraupidae [undescribed form] or Santa Marta Screech-Owl (undescribed form) Megascops [undescribed form], and these are just indexed by the common name (without “undescribed form”, thus SPTA and SMSO). Others are subspecies groups that are indexed by the parent species, such as White-crowned Sparrow (Yellow-billed) Zonotrichia leucophrys nuttalli/pugetensis, which can be found with WCSP or ZOLE.
Slashes – These are used when one is able to identify a bird to a pair of taxa, but not to the species level. Thus, King/Common Eider Somateria spectabilis/mollissima can be found by typing the parent species common name quick find codes (KIEI or COEI) or their Scientific Name Quick Find Codes (SOSP or SOMO).
Spuhs – Spuhs are used when one cannot identify beyond a genus, family, or general group of birds. Common ones include scoter sp., duck sp., Buteo sp., and Phylloscopus sp. None of these have unique codes, but all can be found by just typing the name from the beginning or typing “sp.” and searching through the results.
Remember, any time you can't find something with the quick-find code, you can always search for the full name or part of the name. Searching just "tanager" within the full taxonomy will give all tanagers, including "San Pedro Tanager (undescribed form)".