Should common names of species be capitalized?

I prefer that the official common names of birds (and other species, for that matter) be capitalized, much in the same way that we capitalize the proper names of so many other things. However, some (like wikipedia and various editors), disagree.  But why? Are there good arguments for and against capitalization? And who should decide?

This post is intended to serve as a reference point — a place for me to keep track of my attempt to answer those questions when I revisit the matter — as the subject comes up from time to time among birders and I’m always happy to chime in with my two cents. Hopefully others find it useful, and contribute information in the comments (ahem!).

Why do we capitalize any words? What’s the point? According to most sources, we capitalize words to make them a little bit more special than they would be otherwise, and/or to clarify a distinct entity. For example, here’s one take on capitalization rules, along with a few examples.

The main function of capitals is to focus attention on particular elements within any group of people, places, or things. We can speak of a lake in the middle of the country, or we can be more specific and say Lake Michigan, which distinguishes it from every other lake on earth.

Capitalization Reference List

  • Brand names
  • Companies
  • Days of the week and months of the year
  • Governmental matters
    Congress (but congressional), the U.S. Constitution (but constitutional), the Electoral College, Department of Agriculture. Note: Many authorities do not capitalize federal or state unless it is part of the official title: State Water Resources Control Board, but state water board; Federal Communications Commission, but federal regulations.
  • Historical episodes and eras
    the Inquisition, the American Revolutionary War, the Great Depression
  • Holidays
  • Institutions
    Oxford College, the Juilliard School of Music
  • Manmade structures
    the Empire State Building, the Eiffel Tower, the Titanic
  • Manmade territories
    Berlin, Montana, Cook County
  • Natural and manmade landmarks
    Mount Everest, the Hoover Dam
  • Nicknames and epithets
    Andrew “Old Hickory” Jackson; Babe Ruth, the Sultan of Swat
  • Organizations
    American Center for Law and Justice, Norwegian Ministry of the Environment
  • Planets
    Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, but policies vary on capitalizingearth, and it is usually not capitalized unless it is being discussed specifically as a planet:We learned that Earth travels through space at 66,700 miles per hour.
  • Races, nationalities, and tribes
    Eskimo, Navajo, East Indian, Caucasian, African American (Note: white and black in reference to race are lowercase)
  • Religions and names of deities
    Note: Capitalize the Bible (but biblical). Do not capitalize heaven, hell, the devil, satanic.
  • Special occasions
    the Olympic Games, the Cannes Film Festival
  • Streets and roads

Lowercase Reference List

Here is a list of categories not capitalized unless an item contains a proper noun or proper adjective (or, sometimes, a trademark). In such cases, only the proper noun or adjective is capitalized.

  • Animals
    antelope, black bear, Bengal tiger, yellow-bellied sapsucker, German shepherd
  • Elements
    Always lowercase, even when the name is derived from a proper noun: einsteinium, nobelium, californium
  • Foods
    Lowercase except for brand names, proper nouns and adjectives, or custom-named recipes: Tabasco sauce, Russian dressing, pepper crusted bluefin tuna, Mandy’s Bluefin Surprise
  • Heavenly bodies besides planets
    Never capitalize the moon or the sun.
  • Medical conditions
    Epstein-Barr syndrome, tuberculosis, Parkinson’s disease
  • Minerals
  • Plants, vegetables, and fruits
    poinsettia, Douglas fir, Jerusalem artichoke, organic celery, Golden Delicious apples
  • Seasons and seasonal data
    spring, summertime, the winter solstice, the autumnal equinox, daylight saving time

If you’re hung up on what makes a proper noun… proper, the definition almost helps: According to Merriam-Webster, a proper noun is

a noun that designates a particular being or thing, does not take a limiting modifier, and is usually capitalized in English

Call me crazy, but if we ignore the bit in the definition about capitalization for a moment, it seems fair to categorize official common names as proper nouns!

This is very likely a key point where the traditionalists of grammar bump heads with folks like me: Common names like “blue bill” and “speckle belly” are very different kinds of common names than the sort of common names many advocate should be capitalized. That is, the official English names of species (like those recognized by The American Ornithologists’ Union) such as “Ruddy Duck” and “Greater White-fronted Goose”.

Why even bother capitalizing official common names? Does it really matter? As you can see from above, capitalizing official common names might just be proper grammar if we decide that official common names are proper nouns of any importance. But beyond that, those of us who prefer Ruddy Duck to ruddy duck like the clarity those capital letters bring to words. We capitalize common names because it improves the clarity of written communication! If you write that you saw a yellow warbler, I don’t know if you mean that you saw a warbler that was yellow (of which there are many!) or if you saw a member of the species Setophaga petechia (formerly Dendroica petechia). If you say you saw a Green Finch in your yard, and I had never heard of that species before, those capital letters just gave me a big clue that you aren’t talking about some other green finch.  So yes, it does matter, because clear communication is important.

Now, I’ve heard arguments like “Well, yeah, but it’s usually clear from context so we don’t need the distinction — they both sound the same, after all!”.  Fair enough. But by that logic, we should happily do away with three different spellings of “there”, “their” and “they’re” and various other homonyms. Right? Or maybe precision and clarity matter a bit more than that? Yes? Good, I think it does too.

Birders like to capitalize common names. Do other biologists do this too? Some would say no, but they would be wrong. Plenty of biologists advocate for capitalizing official English names, and many professional organizations are moving in that direction. The real problem is that many taxa don’t have official common/English names. It seems that where official common names do exist, they are capitalized. Here are a few examples, but also see the reference list at the end of this post (I’ll try and add to that list over time):

  1. Birds have official english names that are capitlaized.
    1. The American Ornithologists’ Union capitalizes English names.
    2. The International Ornithological Congress does too.
  2. Fish (at least in North America) too.
    1. American Fisheries Society capitalizes English names.
    2. American Society of Ichthyologists and Herpetologists does too (See their author instructions, which state “Recognized common names of organisms specify unique singulars, are regarded as proper nouns, and must be capitalized.”)
  3. Reptiles and Amphibians? Yup. Capitalized common names.
    1. See 2.2 above and this checklist (PDF)
  4. Mammals
    1. American Society of Mammologists uses caps in their checklist.
    2. The Smithsonian uses caps too.

However, some taxa still don’t have official English names (*), or those official names aren’t capitalized (**):

  1. Plants in North America (see below and the USDA Plants database)*
  2. Insects in North America*
    1. Although species of dragonflies and damselflies (Odonata) do have official English names, which are usually capitalized. Here’s the closest I could find to an official checklist (PDF).
    2. Butterflies too! Here is the NABA checklist.
  3. etc…

Some have proposed less-than-simple rules for how to partially capitalize common names. For example, in 1991 Karstens et al offered the following guidelines for capitalizing common plant names, which largely took hold among botanists as far as I can tell.

VIII. General Guidelines for Capitalization

The following guidelines have been prepared to assist in the use of capitalization of proper nouns and adjectives for common names.

1. Capitalize surnames of individuals used in group names and modifiers…
2. Capitalize names honoring nationalities and human races…
3. Capitalize the names of gods, goddesses, and other religious figures, including names referring to the deity or holy works…
4. Capitalize names suggesting titles, canonizations, and ranks of honor…
NOTE: Capitalization should not be used when specific reference to an individual is not provided…
5. Capitalize international and national place names and national subdivisions such as continents, countries, states, counties, parishes, provinces, and territories…
6. Capitalize local place names, including the names of cities, parks, and other recreational areas…
7. Capitalize geographic directions only when they designate specific areas or regions…
OTE: Mere directional adjectives should not be capitalized
8. Capitalize modifiers that comprise part of a proper name and are written in the singular…

But why not just nail down some official common names, and go with something everyone can remember, like…

Offical English names for each recognized species, where they exist, are to be treated as a proper nouns and capitalized accordingly.

See, no big rule changes, just elevating official common names to the status of the almighty proper noun.


Whare are the arguments for NOT capitalizing official common names? I may have forgotten other arguments against capitalizing official common names, but here’s the running list:

  1. Because dictionaries and traditional grammar rules say not to.
  2. Because it’s confusing when inconsistently applied/enforced.
  3. Because it isn’t fair, since some taxa lack common names.
  4. Because common names are common nouns, not proper nouns.

If I’m missing any arguments against capitalization, please let me know!


So, why don’t we capitalize common names, or the species name for that matter? There are some reasons why we shouldn’t, but here I want to think more about the real reasons why some shun capitalization of common names. I think there are a couple of different factors that play into these anti-capitalization rules, but that it’s largely a matter of our collective, historical feelings towards what are and are not important names for organisms.  Be warned: what you’re about to read should be taken as a hunch — a gut feeling if you will — not something I’ve tried to ground in actual facts 😉

First, capitalization implies elevated status. That part we can take as fact. Here’s the hunch part: and a few generations ago when we were still figuring out how to classify organisms, scientists agreed that we should all hang our hats on binomial nomenclature. Common names were too parochial and indistinct to use in proper scientific writing, and I get the impression that there was probably very little respect paid to them. Too imprecise, too prone to change, too detached from the wonderful taxonomic relationships they were discovering. These layman’s terms were the silly nicknames of the uneducated, and no special status was to be given to them –no way! That, I think, probably set into motion an attitude that the names used by non-scientists in their native language are second class names; unimportant names that had no place in scientific writing. That lead to the custom of not capitalizing them, because doing so would elevate their perceived importance and perhaps devalue the importance of binomial names. Now, remember, this is just a hunch I have, one that I haven’t researched at all, so whether or not there’s any historical evidence to back up this idea is entirely up for debate. If you’re interested and you find anything supporting or refuting this notion, please share!

Second, capitalization implies elevated status, and until recently most of  western culture thought little of animals. They were beneath us; lowly creatures that led a sad, unenlightened, filthy existence.  Man-made structures? Special. Names of associations and corporations? Special. Planets? Special. Hoover Dam? Special. Religious texts? Special. The largest extant species of mammal? blue whale. Not special enough. It wouldn’t at all surprise me if much of our capitalization rules reflect a historical value system that is a bit outdated when it comes to the modern value of species in the English speaking world.

Third, tolerance for either form among scientists (with a few intolerant camps on either side) is perceived as a lack of consensus. I don’t see many grammar rules where multiple options are put on equal footing. There is always a best or most proper way of doing things, and “either way is fine” is rare. Until scientists get more unified in favor of one side or the other, I suspect those who guard the gates of grammar will push hard to maintain the status quo.


Related References

  1. Nelson, Starnes and Warren. 2002. A Capital case for common names of species of fishes–a white crappie or a White Crappie. Fisheries. July 2002. [PDF]
  2. American Fisheries Society publication rules. [PDF]
  3. Common and Scientific Names of Fishes from the United States, Canada, and Mexico. 7th.
  4. IOC World Bird List — Capitalization.
  5. Potter. 1984. On Capitalization of Vernacular Names of Species. Auk. [PDF; Pro-caps response to Atkins 1983; A great read!]
  6. Atkins. 1983. The capitalization of birds’ names. Auk. [PDF; Anti-caps. See Potter 1984 for a response.]
  7. KARTESZ, J. T., & THIERET, J. W. 1991. COMMON NAMES FOR VASCULAR PLANTS: GUIDELINES FOR USE AND APPLICATION. SIDA, Contributions to Botany, 14(3), 421–434. Retrieved from
  8. USDA Plants Database.
  9. Entomological Society of America’s Common Names of Insects Database.
  10. The 370+ comments on this post from the ABA Facebook Page on July 4, 2014 includes some great discussion of the issue regarding birds as well as other organisms. If you have the patience to sift through all the comments 😉
  11. See also the comment thread on this earlier post to the ABA Facebook page on April 22, 2014.



  1. Added a few references shortly after publishing.





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4 Responses to Should common names of species be capitalized?

  1. douglasjgraham says:

    Great blog! Since its all about getting the spelling right, please note the incorrect use of “capitlaized”.

  2. Pingback: Spring 2020 Critter Encounters: Great Horned Owl – Wild Sensibility

  3. Pingback: Serendipity, scrutiny and surprises in the garden – letting nature back in

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