Use of hyphens in group names in birds


J. V. Remsen, Jr. (Acting Chair, South American Classification Committee, American Ornithologists’ Union)


Because Gill & Wright (2006) have removed hyphens from all previously hyphenated group-names, and because the IOC World Bird List (ver. 1 Oct. 2008) has published a vigorous critique of the use of hyphens, I herein provide a brief defense of hyphenated group-names.  I have little intrinsic interest in the subject and never thought that I would have spent several hours on the topic, but as Acting Chair of the American Ornithologists’ Union’s South American Classification Committee and a 25-year member of the AOU’s Committee on Classification and Nomenclature of North and Middle American Birds, I feel obligated to present a response to counteract the misinformation presented at the IOC World Bird List (ver. 1 Oct. 2008).  The framework of the response follows the points and headings, in sequence, at the IOC World Bird List site.


• “Our view is that hyphenated compound names do not, and cannot, reflect phylogenetic relationships accurately, and often misrepresent them. Many cases reflect historical guesses about relationships that were wrong or remain unproven. Compounding the mistakes of pseudotaxonomy are [sic] trespasses on English grammar.”


Beyond the hyperbole, note that a hyphen can reflect phylogeny if it correctly links related taxa.  If that relationship is found incorrect, then the hyphen can be removed. In such cases, the hyphen represents a hypothesis, as does any taxonomic decision, and is subject to review and testing.


• “Reflecting the complexity of the topic, the “hyphenation problem” was the single most contentious issue of the entire IOC English names project.”


Given that some 30 or more people were involved at various stages of creating the Gill-Wright English name list, yet the final product (Gill & Wright 2006) has only two authors, this admission suggests that the arguments presented by Gill and Wright and IOC World Bird List are not as overwhelmingly convincing as the tone of the language indicated in  IOC World Bird List.  Clearly, the other side of the issue is not reflected at IOC World Bird List, although with respect to internal IOC Committee debate, Gill and Wright (2006: 8) stated “After much debate and in the absence of a clear majority in favor of any one of the alternative rules [concerning hyphenation] …“.  In fact, the IOC committee’s original chair, Burt Monroe, was a proponent of hyphenated group-names (e.g., Sibley & Monroe 1990).  Gill et al. (Auk 125: 986) again stated that “these guidelines [on hyphenated bird names] were a consensus-based product of constructive debate by more than 30 experts on the birds of the world, including distinguished members of the AOU and their peers in sister societies on other continents.”  I suggest that this is an overstatement and point out that many distinguished members of the AOU and their peers in sister societies on other continents are not part of that consensus.




• “In terms of English grammar, it is incorrect to use a hyphen to create a new compound noun from an adjective (including participles) and a noun, or a noun acting as an adjective coupled to a noun.  Thus, ‘whistling-duck,’ i.e. a duck that whistles, and ‘night-heron,’ i.e. a heron of the night, are not correct constructions. In this sense, the use of hyphens to create new compound adjective-noun names, as recommended by Parkes (1978) is a novel, incorrect and, we assert, an undesirable practice if the other rules of formulation of the English names of birds are applied correctly.”


I am unable to find any such rule in the first six authoritative English grammar texts and writing manuals consulted; see Grammar Details.  I also suspect that if this usage were such a violation of grammar, a learned person such as Ken Parkes would have recognized this, as would the dozens of journal editors and thousands of ornithologists who have used hyphenated group-names.


• “Consider a group of green suitcases of different sizes, all made by the same manufacturer. Why use "big green-suitcase" and “little green-suitcase” when "big green suitcase" and “little green suitcase” are simpler and perfectly clear? Similarly, Long-tailed Wood Partridge is clear without an extra hyphen (wood-partridge), as are Maroon Shining Parrot, Wilson's Storm Petrel, African Green Pigeon, and Biak Black Flycatcher.”


The “suitcase” example refers to a series of adjectives that modify a noun in a sentence, not a compound noun or name.  Rules of grammar in sentence structure are fairly rigid and may not apply to formation of names.  Further, strictly hypothetically, if “green suitcase” became such a frequent combination that the two words clearly referred to a single item in everyday speech, then Strunk & White and other sources would point out that they might go through the same evolution as “wild life,” with a transitional period of hyphenation as ”wild-life” before becoming “wildlife.”


Among the specific examples given is one that illustrates how hyphens can remove ambiguity.  In “Maroon Shining Parrot”, a hyphenated group-name “Shining-Parrot” makes it clear that the parrot is not “shining maroon.”  In fact, if those three words were written in text (“maroon shining parrot”) a hyphen or comma would be required for clarity, i.e., either “maroon, shining parrot” for a parrot that is both maroon and shining, “maroon-shining parrot” for a parrot that shines maroon, or “maroon shining-parrot” to indicate that a shining-parrot is a class of parrot of which one is maroon.  Also, a hyphenated “Storm-Petrel” signifies that these birds are not petrels in the Procellariidae, but species in a separate family, Hydrobatidae.  Finally, in the same genus as African Green-Pigeon is the “Little Green-Pigeon,” in which case the hyphen removes any doubt as to which words modify which, as well as defining “Green-Pigeon” as group name that refers only to species in the genus Treron (whereas unhyphenated Green Pigeon does not make this clear). 


Like it or not, most non-ornithological journals and texts do not put official names in upper case, despite the obvious advantage of distinguishing, for example, a “Singing Quail” from a “singing quail,” or my personal favorite, a “Hairy Woodpecker” from a “hairy woodpecker” (the latter prompting a revolution in vertebrate classification).  Use of hyphens preemptively reduces some of the ambiguity, as in the above example: a “maroon shining parrot” or “little green pigeon” without the use of upper-case letters presents obvious problems, whereas “maroon shining-parrot” and “little green-pigeon” signals to the non-ornithologist that the hyphenated parts of the name refer to a class of parrots or pigeons.


Absence of hyphens creates some unfortunately ambiguous names in terms of interpretation, e.g., “Shade Bush Warbler” for Cettia parens, “Aberrant Bush Warbler” for C. flavolivacea, “Ja River Scrub Warbler” for Bradypterus grandis, “Friendly Bush Warbler” for B. accentor, and “Laura’s Woodland Warbler” for Phylloscopus laurae (to pick out a few examples just from Old World Warblers).  More examples from Phasianidae: White Eared Pheasant, Blue Eared Pheasant, Jungle Bush Quail, Painted Bush Quail, Rock Bush Quail, Udzungwa Forest Partridge.  Examples from the Gruidae:  Black Crowned Crane, Gray Crowned Crane.  These represent mistakes in grammar by anyone’s criteria.


• “Use of a hyphen to create a new compound noun by joining two categorically related nouns (in apposition) is grammatically correct. Thus director-actor, city-state, or singer-songwriter, are allowed and standard features of the written English language. Corresponding to these examples, compound bird-bird names, such as “tit-spinetail” and “eagle-owl” also are correct constructions, as recommended in the IOC guidelines.”


The author claims to have a knowledge of grammar and that grammar supports the author’s position.  However, two and perhaps all three examples given are not nouns in apposition, but hybrid combinations that reflect dual roles (a “director-actor” is both a director and actor).  This type of hyphen is clearly shorthand for “and.”  Thus, the three English examples given above as “corresponding to these examples” are not analogous to the bird name examples. “Tit-Spinetail” and “Eagle-Owl” are not hybrids or combinations, i.e., not “part eagle” and “part owl,” but rather the first word modifies the second.


More generally, new nouns are constantly added to the technical literature, many of which are compound words of novel construction.  Whether rules of grammar per se apply to invention of new nouns is, in my opinion, an open question.



• “The various screech owls and golden plovers constitute "groups" of species that are theoretically more closely related to each other than to other taxa. They are supposedly monophyletic. But accurate linking of English names to monophyletic “groups,” as proposed by Parkes (1978), is almost impossible on a worldwide basis.  In a sense, formal English group names potentially parallel equivalent scientific names, such as a genus or subgenus. But the parallel is limited and doing so is not a desirable goal for many reasons. Among them, concordance of English names and avian genera is low for many historical reasons, with the result that only a small fraction of the related birds of the world share an English group name. Forcing consistency between English names and genera would require changing the names of thousands of species.”


This is an overstatement.  Parkes (1978) did not propose to link all English names to monophyletic groups.  His only targets were cases in which a group name was already in use but without a hyphen.  Neither Parkes (1978) nor the AOU has made any recommendations beyond use of hyphens in group names in which the group is proposed to be monophyletic.  Anyone who has followed the AOU committees, of which Parkes was a member, knows that stability in English names is a primary consideration.  Only about 140 of 2048 English names in North America are affected by the hyphenation of group names, and of these, about 20 are also hyphenated in the IOC List, leaving about 6%  as the source of the controversy.


• “For example, the African Grey Flycatcher (Bradornis microrhynchus) is related to the Ethiopian Grey Flycatcher (Bradornis pumilus), but not to the Little Grey Flycatcher (Muscicapa epulata) also found in Africa, or to the American Gray Flycatcher (Empidonax oberholseri) of North America. Which “gray flycatchers” should we hyphenate?  Simple consistency would favor hyphenating them all, creating a group of unrelated species. Hyphenating only the two related species of Bradornis would leave two unhyphenated species of “gray flycatchers,” subject to new studies.”


The AOU system does not add hyphens to all species with the same “last name,” but only to species (a) proposed to form a monophyletic group that had existing double last names, such as the Whistling Ducks, or (b) recently split species for which the original single name was retained because of an absence of established names for the newly split species, such as the Slaty Antshrikes.  This system explicitly does not use a hyphen when to do so would imply false relationships, e.g., Great Blue Heron and Little Blue Heron have no hyphens.  If B. pumilus is treated as a separate species from B. microrhynchus, then the AOU system might indeed use a hyphen to indicate sister-species status.  The other two species would not be hyphenated.  Leaving two species of “gray flycatchers” unhyphenated thus signals that they have nothing to do with each other or with the hyphenated Bradornis “Gray-Flycatchers.”  The Gill-Wright system provides no information on relationships, or misleadingly implies that these flycatchers are related because they have the same “last names,” whereas the Parkes/AOU system explicitly identifies relationships and non-relationships.


• “The implications, directly or indirectly, that hyphenated ‘groups’ are natural groups also can be misleading.  For example, hyphenated group names are applied to unrelated taxa in different genera, such as the unrelated ‘wood-rails’ in Latin America (Aramides) and in Madagascar (Canirallus). Another example are [sic] the unrelated ‘palm-swifts’ in the New World (Tachornis) and in the Old World (Cypsiurus). ‘Mountain-finches’ are in the genus Leucosticte (along with ‘rosy-finches’) and also in the genus Poospiza (along with   ‘warbling-finches’).”


I agree that the “wood-rails,” “palm-swifts,” and “mountain-finches” indeed are examples of misleading hyphens.  However, note that their removal still leaves the names with similar misleading connotations. It is only natural to think that birds with the last name “Wood Rail” form a natural group, with or without the hyphen.  Hyphenated or not, using just the English names implies a relationship that is incorrect.  A possible solution would be to make “woodrail” a single word for one genus and leave “wood-rail” for the other.  The IOC system retains hyphenated group names for species that have double last names consisting of two bird names, e.g., Hawk-Eagle, Quail-Dove, Nightingale-Thrush, etc.  The reason given for this is “a hyphen should be inserted to signify that the taxon belongs to the family of the second word” (Gill and Wright 2006: 8), not phylogenetic relationships.  However, these do not differ grammatically from other noun-to-noun names that are de-hyphenated, e.g. Wood Wren and Brush Finch.  Further, not hyphenating the latter creates potential ambiguity.  For example, “Tepui Brush Finch” could refer to a Brush Finch of the Tepuis or a Finch hat lives in Tepui Brush.  Without the hyphen, it is impossible to tell, and because the former meaning is the intended one, absence of a hyphen is grammatically incorrect.


* I concur with Gill and Wright than retention of hyphens in “Bird-Bird” last names is a good idea to avoid confusion, regardless of phylogenetic relationships.  Deleting the hyphen from for example, Ornate Hawk-Eagle, produces names that are potentially confusing … what exactly is an “Ornate Hawk Eagle,” a Hawk or an Eagle?


• “In other cases, hyphens are used for subsets of congeneric species that share an English group name for historical reasons in the absence of convincing phylogenetic analysis.  For example, Eastern Wood-Pewee and Western Wood-Pewee are inferred to be sister species, even though we lack a solid phylogeny of the genus Contopus.  Rather, this statement is a holdover from an early era when we assumed that eastern and western North American counterparts were sister species, which can be incorrect.”


Consider the hyphen as a hypothesis that is strongly supported in this case by morphological, behavioral, biogeographical, and vocal data.  If that hypothesis were refuted by genetic data, then I would personally vote for a proposal to remove the “Wood” from their names.  Both AOU committees are amenable to proposals from anyone, at any time, and of any kind.  Proposals are considered on a case-by-case basis based on their individual merit.


• “Even more uncertain are the relationships among the 11 species in the Neotropical genus Knipolegus, only 7 of which are named “Black-Tyrants.” Finally, consider the use of “tody-tyrant” for some species of Hemitriccus, but “pygmy-tyrant” for other species of Hemitriccus as well as for species in five other genera (Pseudotriccus, Euscarthmus, Myiornis, Lophotriccus, Atalotriccus) of tyrant-flycatchers.”


This is indeed a mess, but as noted above, removal of the hyphens does not solve the problem.  It is only natural to assume that all birds called “Pygmy Tyrant” are more closely related to one another than to flycatchers with different last names, whether they are all called “Pygmy Tyrant” or “Pygmy-Tyrant.”  At least the use of hyphens makes it clear when these are proposed to be true relationships.


A minor point here is that the differences in the last names in such cases typically reflecting a past history of being placed in a separate genus.  For example, current Hemitriccus contains mainly species formerly placed in a separate genus, Idioptilon, which for decades were called Pygmy-Tyrants, whereas the species in narrowly defined Hemitriccus were called Tody-Tyrants.




• “Given the dynamic and uncertain state of our knowledge about relationships among bird species, we prefer to follow plain, correct, and intuitive English, rather than to overload the orthography of English names of birds with phylogenetic inference through hyphens.”


The AOU committees, as well as some unknown number of members of the IOC committee, have a different preference, namely to use hyphens in existing group-names to indicate that existing data reflect monophyly of that group. What Gill & Wright do not seem to recognize is that removal of hyphens does not remove the problem – birds with the same “last name” will naturally be assumed to be related, and only hyphens can clarify when this is or is not the case.


Summary.  The IOC World List’s main points are that (1) hyphenating adjectives to nouns to form group names is grammatically incorrect, and (2) such hyphens can be misleading as to relationships.  I here argue that (1) no evidence exists that I can find that such constructions are grammatically incorrect and plenty of evidence that use of hyphens to remove ambiguity is not only correct but also grammatically required, and (2) removal of hyphens does not remove the problem of incorrect inference of phylogenetic relationships.



Addendum:  Gill et al. (2009.  Wilson J. Orn. 121: 652-655) have recently put many of these ideas in print.  Although they cited this web page as a pers. comm. from someone else, they did not address the many of the points outlined herein, especially:


(1) Removal of hyphens does not remove the connotation that species with similar names are related, whereas insertion of hyphens makes such cases explicit.  This point essentially eviscerates their main point, as reflected in their title “On hyphens and phylogeny.”


(2) If a phylogenetic hypothesis is falsified, then the hyphen can be removed (e.g., if the night heron genera do not form a monophyletic group).


(3) Hyphens reduce ambiguity (i.e., their proper grammatical usage), particularly in lower-cased bird names in the vast majority of scientific journals and popular literature.


Further, they continue to ignore the point that hyphens are not inserted in every species’ name in a genus, but only in the names of some sets of species thought to form a monophyletic group.  No one has ever proposed that all such groups have hyphenated names, so their examples such as “rough-winged-swallows” are obvious “straw man” arguments, put forth not in the interests of objective discussion, but only to advocate their own agenda.