Every late summer to fall, major ornithological entities publish their taxonomic updates. Updates include newly added bird species, which may be newly discovered species, or more commonly the elevation of subspecies or subspecies groups to species ranks. The latter is referred to as a “split.” The updates also include a number of “lumps,” where it is decided that two or more species are not sufficiently different from each other, and therefore better treated as subspecies or other forms of a single species. If listing is your game, splits have the potential to increase your list total, while lumps can decrease it. However, species splits and lumps are not the only updates that are published. They also include new ways to arrange species into higher taxonomic ranks, such as genera, families, and orders. While this type of update does not affect the species number, it can result in a change in species sequence and scientific name.
In the following, I will summarize the recent decisions made by two ruling bodies. The first is the North American Checklist Committee (NACC) of the American Ornithological Society, which published its update in the journal Ornithology, volume 141, pages 1-21. This is the 65th supplement to their originally published checklist, in the following abbreviated as the “AOS list.” The coverage of the AOS list is North America north of the Panama-Colombia border and also includes Greenland and the Hawaiian Islands. (The AOS also has a South American Checklist Committee, which operates independently and not always arrives at the same decisions.) Taxonomic changes to the AOS list are usually accepted by the American Birding Association for
their own ABA checklist. Updates to the AOS list also include the addition of vagrants from other parts of the world; these are not the subject of this article.
The other checklist update that I will discuss here is the one that applies to eBird. It is based on a world checklist that was published by James Clements and updated several times before his death in 2005. It has since been taken over by the Cornell Lab of Ornithology but is still referred to as the Clements list. For North America, the Clements list often follows decisions made by the AOS NACC, but there are some discrepancies, as you will see below.
There are other checklists of worldwide coverage, such as the IOC World Bird List, the Howard & Moore Complete Checklist of the Birds of the World, and the list by HBW Alive/Bird Life International. I personally do not follow these; therefore, I will not mention them further.
So, what are the splits and lumps that affect us at the local and regional levels? The bad news first: AOS and Clements agree that Hoary Redpoll is no longer a species. All forms of redpoll (Common, Hoary aka Arctic, and Lesser Redpoll) have been lumped into one species just called Redpoll (Acanthis flammea) with subspecies groups that still represent the former species. Those of you who struggled with identifying a Hoary Redpoll in a flock of commons may be glad, but many Illinois listers will lose a species here.
If your focus is only Illinois, you will not gain list numbers from the splits even though they affect what species are called. The most notable ones are: Barn Owl (Tyto alba), which occurs on many continents, has been split into three forms. As a result, the New World form is now called American Barn Owl (T. furcata). In the Old World, we
now have Western (T. alba) and Eastern (T. javanica) Barn Owl, with a boundary approximately between the Middle East and the rest of Asia. This split is recognized by the AOS and by Clements.
House Wren (Troglodytes aedon) has long been anticipated to split, and it finally happened in both the AOS and Clements lists. Not only did they split it into the northern (T. aedon) and the southern (T. musculus) forms on the mainland, but they also spun off five island forms. Our species is now called the Northern House Wren. The species in Central and South America (south of approximately central Mexico) is predictably called the Southern House Wren.
A split that was only adopted by Clements, but not (yet) by the AOS, is that of Herring Gull (Larus argentatus) into four species, three of which have potential to occur in North America. The nominate form in Europe is now the European Herring Gull (L. argentatus). It probably
occurs in small numbers on the American continent. The species that breeds in North America and is normally encountered here is the American Herring Gull (L. smithsonianus), and the form breeding along the western Pacific rim is Vega Gull (L. vegae). This latter form is occasionally found in North America and should be looked for as a rarity. The fourth split species is Mongolian Gull (L. mongolicus) of Inner Asia, which is unlikely to wander to North America.
The final split of a species occurring in Illinois is that of American Pipit (Anthus rubescens). No change will be noted locally, but Siberian Pipit (A. japonicus) of East Asia is now a separate species. It wanders in small numbers to Alaska and along the American Pacific coast.
On a worldwide scale, the number of species on the Clements list has increased by 128, with 141 species gained by splits and 16 lost by lumps. I don’t have space to list them all and will just name a few noteworthy splits:
Burchell’s Coucal (Centropus burchellii) split from White-browed Coucal (C. superciliosus)
· Cory’s Shearwater split into Cory’s Shearwater (now Calonectris borealis) and Scopoli’s Shearwater (C. diomedea, which was the scientific name of the combined species)
· Cocos Booby (Sula brewsteri) split from Brown Booby (Sula leucogaster)
· Plain Xenops of the American tropics split into three: Northern Plain-Xenops (Xenops
mexicanus), Amazonian Plain-Xenops (X. genibarbis), and Atlantic Plain-Xenops (X. minutus)
· Eurasian Nutcracker split into Northern Nutcracker (Nucifraga caryocatactes) and Southern Nutcracker (N. hemispila)
· Rock Martin of Africa and the Middle East split into three: Pale Crag-Martin (Ptyonoprogne
obsoleta), Red-throated Crag-Martin (P. rufigula), and Southern Crag-Martin (P. fuligula)
· Red-rumped Swallow split into European (Cecropis rufula), African (C. melanocrissus), and Eastern (C. daurica) Red-rumped Swallow.
· Island Thrush (Turdus poliocephalus) of the South Seas is split into no less than 17 species!
As mentioned above, splits and lumps are not the only changes in the updated taxonomies. Some reshuffling of species within taxonomic units also results in a different sequence, and often a different scientific name. However, even higher-level changes are possible. At the highest level, separate orders for the nightjars (Caprimulgiformes), potoos (Nyctibiiformes), Oilbird (Steatornithiformes), frogmouths (Podargidiformes), owlet-nightjars (Aegotheliformes), and swifts, treeswifts, and hummingbirds (Apodiformes) were resurrected by Clements, after they had been grouped in a single order (Caprimulgiformes) for several years. The AOS kept them as separate orders all along.
Orders that were moved around include flamingos (Pheonicopteriformes) and grebes (Podicepidiformes), both of which now follow the last family in Charadriiformes, i.e., gulls and terns (Laridae). Within the order Pelecaniformes, the families were shuffled and now follow the sequence of ibises and spoonbills (Threskiornithidae), herons (Ardeidae), Hamerkop (Scopidae),
Shoebill (Balaeniciptidae), and pelicans (Pelecanidae).
Clements added two additional families to its list: A new family, Erythrocercidae, was created for three species of African flycatchers, and two species of Spotted Creeper (from Africa and South Asia) were moved from the treecreepers (Certhiidae) into their own family,
Salpornithidae.
Changes at the genus level are much more numerous, and I will mention only one family, where the changes are relevant to local species. In the hawk family (Accipitridae), the genus Accipiter was split into five by Clements but not AOS. This means that Cooper’s Hawk and American Goshawk are no longer members of the genus Accipiter, but of Astur. In addition, the sequence of genera was updated, with harriers (genus Circus) now after the Accipiter group, and
Mississippi Kite (genus Ictinia) after the sea eagles (e.g., Bald Eagle), among others. This family is one where Clements and the AOS list continue to disagree.
Finally, there are English name changes that are not driven by systematic changes but adaptations by the America-centered organizations to local use. Few of these affect North American species, but examples that might be familiar to some of you are Sargasso Shearwater (from Audubon’s Shearwater), Reed Cormorant (from Long-tailed Cormorant), Eurasian Bittern (from Great Bittern), Purple Roller (from Rufous-crowned Roller), and White-crested
Helmetshrike (from White Helmetshrike). Furthermore, all species in genus Amazona now carry the epithet of Amazon instead of Parrot (e.g., Red-crowned Amazon instead of Red-crowned Parrot).
I realize that many birders are not fond of these taxonomic changes. Losing species on lists to lumps is not fun. Learning new names takes time. However, we need to embrace the fact that the bird taxonomy of the present is just a snapshot of scientific knowledge based on existing
data that continues to evolve. The field of molecular genetics is generating an increasing amount of new data that leads to new interpretations every year. Follow the science!