All of eBird's tools require a standardized taxonomy—a shared understanding of what each bird name means. If we don't all mean the same thing when we say "Peregrine Falcon", it's impossible to compare records from around the world. This page explains the details of all the different aspects of our taxonomy.

Quick Links

Bird Names

Taxonomic Categories


Subspecies, Groups, and ISSFs

Hybrids and Intergrades

Spuhs and Slashes



Taxonomic Updates


Bird Names in eBird

Every species in eBird has both a Common Name and a Scientific Name. Common Names exist for every species in English, and are also translated into dozens of other languages. Learn more about bird names in eBird here.

In addition, every bird (and known organism!) has a scientific name. These names reflect the evolutionary history of bird species, allowing us to logically trace their relationships and ancestry. Scientific names include a Genus name, which may be applied to several species (e.g., Junco), and a species name (e.g., hyemalis). The two names together describe a unique species (e.g., Junco hyemalis). A subspecies is a recognizable form within a species that interbreeds (more or less) freely with other members of the species. Subspecies names are added following the species name, so Junco hyemalis carolinensis describes the southern Appalachian subspecies of Dark-eyed Junco. 

Taxonomic categories

The eBird taxonomy includes every field-identifiable taxon relevant for birders to report. These taxonomic categories are dealt with differently in eBird output and are clearly indicated in the downloadable file below. The eight eBird categories are:

  • Species: e.g., Tundra Swan

  • Subspecies (ISSF or Identifiable Sub-specific Group): Identifiable subspecies or group of subspecies, e.g., Tundra Swan (Bewick’s) or Tundra Swan (Whistling)

  • Hybrid: Hybrid between two species, e.g., Tundra x Trumpeter Swan (hybrid)

  • Intergrade: Hybrid between two subspecies or subspecies groups, e.g., Tundra Swan (Whistling x Bewick’s) 

  • Spuh:  Genus or identification at broad level, e.g., swan sp.
  • Slash: Identification to Species-pair, e.g., Tundra/Trumpeter Swan

  • Domestic: Distinctly-plumaged domesticated varieties that may be free-flying (these do not count on personal lists) e.g., Mallard (Domestic type)

  • Form: Miscellaneous other taxa, including recently-described species yet to be accepted or distinctive forms that are not universally accepted, e.g., Red-tailed Hawk (abieticola), Upland Goose (Bar-breasted)

See below for additional information on each category.


Our species and subspecies taxonomy uses the Clements Checklist, a global bird taxonomy which follows regional authorities. In the Americas, the Clements Checklist largely defers to the two AOS committees–the North American Classification Committee (NACC) and the South American Classification Committee (SACC)–with the goal of near-complete compliance. The few departures are listed in detail in Appendix A (NACC) and Appendix B (SACC). 

The eBird taxonomy (v2023) is current with Clements v2023. Clements updates occur once a year in the late fall, are documented in full, and can be downloaded here. eBird taxonomic updates coincide with Clements updates.

Subspecies (ISSF or Identifiable Sub-specific Group)

The Clements checklist includes identifiable groups, which we also use in eBird. Identifiable groups–which eBird refers to as ISSFs (Identifiable Subspecific Forms)–are taxonomic units below the species level that follow subspecific boundaries as defined by the Clements checklist. 

These may be a single subspecies like:

Dark-eyed Junco (White-winged) — Junco hyemalis aikeni

a subspecies pair:

Dark-eyed Junco (Slate-colored) — Junco hyemalis hyemalis/carolinensis

or a group of subspecies which we define:

Dark-eyed Junco (Oregon) — Junco hyemalis [oreganus Group]

Dark-eyed Junco (Slate Colored)Dark-eyed Junco (Oregon)

Dark-eyed Junco (Slate-colored), left, and Dark-eyed Junco (Oregon), right. Margaret Viens/Macaulay Library at the Cornell Lab (ML83718271) and Rebecca Matsuraba/Macaulay Library at the Cornell Lab (ML87899961). 

These groups allow eBirders to note identifiable differences and study the distribution and abundance of different subspecific forms where they both occur. Not only can this information be helpful to researchers and conservationists, but if the group is later split, eBird will automatically update your lists for you. For example, if you live in Texas, where Yellow-rumped Warblers could be either the Myrtle or Audubon's subspecies, what will happen when they are split? Any sightings you enter as "Yellow-rumped Warbler (Myrtle)" will be moved to the new species "Myrtle Warbler" and likewise for Audubon's, but any sightings you entered as just "Yellow-rumped Warbler" would become a slash: Myrtle/Audubon's Warbler. 

We encourage eBirders to use these groups to report whenever possible; you can always add any species or group to your checklist by searching the full taxonomy on eBird Mobile or using the “Add a species” box on the web. If you are not comfortable, or do not understand what the subspecies group refers to, just enter your sightings at the species level.

Hybrids and intergrades

We include known hybrids from the wild that are frequent enough and distinctive enough to be reported by birders. These range from common hybrids like "Western x Glaucous-winged Gull" and "Eurasian X American Wigeon" to much rarer ones like "Berylline x Rivoli’s Hummingbird" to "White-throated Sparrow x Dark-eyed Junco." Note that hybrid names follow taxonomic sequence, with the first species in sequence coming first in the hybrid name. You can review available hybrids by searching for “(hybrid)” in the “Find a species” text box during checklist entry.

Ross's x Cackling Goose (Hybrid)

Ross's X Cackling Goose (hybrid) by Peter Burke (ML81988061)

We also include intergrades, where hybridization between two subspecies or ISSFs produces an identifiable cross. For example, since the two forms of Green-winged Teal (American and Eurasian) are distinctive and each is treated as an ISSF in the eBird taxonomy, we consider the hybrid result of a mixed pairing to be an intergrade.

Spuhs and slashes

Every time you go birding, you’ll see some birds that you can’t identify. eBirders can log these uncertain sightings in eBird using ‘spuhs’ (e.g., hawk sp.—an unidentified hawk), or ‘slashes’ (e.g., Greater/Lesser Scaup—a duck that you knew was one of these two species, but not sure precisely which).

Surf/Black Scoters

Surf/Black Scoters by Nick Newberry/Macaulay Library (ML127294601)

When multiple species are involved, we list these as “spuhs,” spelled “sp.” Examples include Empidonax sp., scoter sp., Accipiter sp., or duck sp. When there are only two members of a species pair are possible, we list these as a “slash.” Examples include Common/Thick-billed Murre, Greater/Lesser Yellowlegs, and Parasitic/Pomarine Jaeger. 

We encourage eBirders to make use of these options. Spuhs and slashes help us know when there are individuals or aggregations of birds that are just too far away or briefly seen to be identified, allowing us to differentiate when a species may be there (but was too far or too difficult to identity), from when it truly was not there.


We include options to enter free-flying individuals of domestic stock. Note that domestic types in eBird are phenotypes, and thus are identifiable as birds of domestic origin by field marks not typical of wild populations. “Domestic type” always refers to a distinct lineage and is not a value judgment, so it *should not* be used to report birds that are identical to wild birds but that you presume to be escapees from a cage or pen. 

Muscovy Duck (wild)Muscovy Duck (feral)

Muscovy Duck, left, and Muscovy Duck (Established Feral), right. Henry Cook/Macaulay Library at the Cornell Lab (ML83693491) and Susan Young/Macaulay Library at the Cornell Lab (ML52378881). 

Domestics are generally not counted on eBird lists, but there are two exceptions. Rock Pigeon (Feral Pigeon) represents the wild, free-flying pigeons that occur in cities worldwide; they are distinct from “Rock Pigeon (Wild type),” which corresponds to birds in the native range with wild type appearance and behavior. The general “Rock Pigeon” is an option for individuals of uncertain status.

“Muscovy Duck (Established Feral)” represents feral type birds that have self-sustaining populations in areas like Florida; “Muscovy Duck (Domestic type)” is for the phenotypically identical domestic populations that are not established where they occur. “Muscovy Duck” is for wild birds throughout their native range in the Neotropics.


The eBird Taxonomy includes all taxa available in eBird; the Clements Checklist is the backbone of the eBird Taxonomy and includes just species, subspecies groups, and subspecies (subspecies are not available in the eBird taxonomy), and the eBird/Clements Checklist includes both lists merged together. To download the eBird taxonomy, the Clements taxonomy, or a merged version, please visit the Clements/eBird checklist download page.  

Taxonomic Updates

As with all science, both the Clements taxonomy and the eBird taxonomy are works in progress. New species are described each year, and new splits or lumps are regularly justified. We welcome assistance in keeping up with these rapid advances in bird taxonomy, especially from South America and the Old World. 

If you notice any species, subspecies, hybrids, or “spuhs” that are absent, or if you find any errors in spelling, nomenclature, taxonomy, or sequence, please let us know by submitting a help ticket above. Note that since the eBird and Clements taxonomies update in August, please deliver feedback by early May for changes to be incorporated in a given year’s update. 

The eBird taxonomy is updated once a year in October. You can read the annual updates here:

* Updates prior to August 2012 are no longer available online


Appendix A: NACC Departures (PDF)—current through 2018

Appendix B: SACC Departures (PDF)—current through 2018

Appendix C: Forms (PDF)