In general, a compound word is a combination of two words that in theory could be spelled as one word, as two words, or as two words hyphenated (e.g., Woodpigeon, Wood-Pigeon, or Wood Pigeon. A fourth alternative spelling of bird names is to follow the hyphen with a lowercase letter (e.g., Wood-pigeon). The problem is complicated by the use of variant spellings over many years. For example, Audubon used hyphens freely (as in Meadow-lark), in cases where now single words are used. Now, some American ornithologists, in particular, use hyphens to define sets of species presumed to be closely related, for example Wood-Pewee and Ground-Dove. Go directly to On Hyphens and Phylogeny for the IOC's view on this practice.
The IOC committee adopted the following spelling rules:
A. Single words.
In keeping with the trend toward greater use of single words that improve distinctiveness for the species, compound names are best spelled as single words:
- IF the second word is “bird” (e.g., Bluebird, Tropicbird, Secretarybird) or its equivalent (e.g., Woodcock, Waterhen); or
- IF the second word is a body part of a bird (e.g., Hookbill, Bufflehead, Yellowlegs); or
- IF the name describes a birds call or song (e.g., Chickadee, Dickcissel, Poorwill, Killdeer); or
- IF the second word describes a birds behavior or activity (e.g., Flycatcher, Roadrunner, Honeyeater); or
NOTE: The only exception to the above cases is to use a hyphen if otherwise the name would be hard to pronounce or would look odd (e.g., White-eye, Wattle-eye, Thick-knee, Huet-huet, Chuck-wills-widow). Whip-poor-will was deemed borderline and the committee decided to follow perceived general usage.
- IF the second word is a kind of bird (e.g., Nighthawk, Bushtit, Waterthrush, Meadowlark), but the taxon is not a member of the bird family named.
For example, a Meadowlark is not a Lark; a Cuckooshrike is not a Shrike. Thus the name should not be spelled as two words without a hyphen (e.g., Meadow Lark), or spelled with a hyphen followed by a capital letter (e.g., Cuckoo-Shrike). Rather, a single word is used except where it would be hard to pronounce or look odd (e.g., Silky-flycatcher, Stone-curlew, Flycatcher-shrike).
Conversely, if the second word is a type of bird and the taxon is deemed to be a member of that bird family, the name would be spelled with two words, either without a hyphen or with a hyphen followed by a capital letter (e.g., Bush Lark, Eagle-Owl). Converting these to single words states, in effect, that the taxon is not in that family but is rather something different. Exceptions have been made in a few cases where long and widespread usage dictates a single word, such as Goldfinch, Skylark, Woodlark, and Sparrowhawk. These and other cases are under review for potential revision.
B. Two words.
The most difficult problem is with compound words that are not to be spelled as single words. The choice in most such cases was whether to hyphenate the two words or not, and this became the single most contentious point in the entire project because the committee members had very different attitudes toward the hyphen.
At one extreme was the position that a hyphen should never be used except when absolutely necessary to clarify pronunciation or make a necessary word connection. Tied to this position were arguments that hyphens tend to violate otherwise ordinary rules of grammar; that common usage usually does not support hyphens; and that hyphens violate the principle that names should be simple.
At the other extreme is the view that hyphens should be used liberally in bird nomenclature to indicate relationships among taxa, and that if two or more taxa have the same last name the words should be hyphenated.
The committee decided that a middle ground was essential. It adopted the following rules for the use and spelling of two-word compound names:
- Two words should be used to spell all names not falling within the rules for single-word names.
- A hyphen should not be used as a general rule, and both words should begin with capital letters (e.g., Black Tyrant, Screech Owl, Green Pigeon, Storm Petrel, Wood Partridge). This rule is contrary to the broadly used names of Sibley and Monroe (1990) and currently of the AOU. We attempted to use hyphens to denote group names, despite reservations of several committees, but finally rejected the practice for two primary reasons:
- In standard English, hyphens should not be used to link a noun with an adjective that modifies it to create a new noun. Rather, compound nouns are formed (Yellowstone) or the two words remain separate but are used as one (French Poodle).
- The goal of creating group names by adding hyphens is intrinsically unstable, confusing, and impractical. It requires that we add a hyphen when one species, such as Warbling Vireo, is split into a group of two species (Eastern Warbling-Vireo and Western Warbling-Vireo), and that we remove the hyphen when two such species are lumped. Hyphens then must be added or subtracted in concert with changes in species taxonomy, which only a small group of specialists will be able to track in something approaching real time. Nonornithologists including editors of bird books will not have the ability or time to check the latest taxonomy to use hyphens "correctly" and thus will tend to be out of grace.
- Where both nouns are the names of birds or bird families a hyphen should be inserted to signify that the taxon belongs to the family of the second word, not the first (e.g., Eagle-Owl, Nightingale-Thrush). This conforms to correct English use of hyphens.
- If a name is of a taxon that is not a member of the stated bird family, the letter after the hyphen should be lowercase to clarify that status (e.g., Flycatcher-shrike). This is a companion to the rule, described above, applicable to single-word names that hyphenates them to avoid confusion, as in Silky-flycatcher or Stone-curlew.
- If application of any of the above rules would produce a name that is contrary to long-established and widespread usage, the rule may be modified or not applied. For example, Goldfinch, Skylark, Steamerduck, and Sparrowhawk-all taxa that are within the family name stated and thus do not come within the single-word rules described above-can nevertheless be spelled as single words, despite #1, because of long usage.