The 62nd Supplement of the American Ornithological Society’s Check-list of North American Birds (published today in Ornithology) includes many updates to the continent's bird species classification. Below are some highlights of this year's supplement. These include species splits in Mew Gull, Barred Owl and Sedge Wren. There is also a transfer back into an old genus of Ruby-crowned Kinglet. Also, the revision of the linear sequence for passerine families. The Check-list has been published since 1886. It is maintained annually by the AOS's North American Classification Committee, the official authority on the classification and names of the birds in the region. This is used by both birders and professional ornithologists.You can find the complete Check-list Supplement at https:/ / Academic. oup. oup. 1093/ ornithology/ukab037/6309332Species SplitsSplitting of Cinereous Owl and Barred Owl (Proposal 2021C-8)The Barred Owl (Strix varia), based primarily on vocalization differences, is being divided into two species. The Barred Owl retains its English name and scientific names for the U.S. and Canadian population, while the Cinereous Owl (Strix.sartorii) will be its Mexican counterpart. Terry Chesser, U.S. Geological Survey chair, explains that vocalizations are crucial for species recognition in owls. Nathan Pieplow (University of Colorado Boulder), and Andrew Spencer (Cornell Laboratory of Ornithology) proposed splitting the Barred Owl into two species. They focused on key differences in their rhythms and series songs. In particular, they highlighted the series song's syncopated beginning, uniform pitch, and lack of a long 'hoowah' at the end. The Barred Owl's series song has the loudest and highest notes at the end. In the sartorii's, the loudest and most loud notes are in the middle.Pieplow and his colleagues were shocked and dismayed to discover that this species has seen a drastic decline in its range and was returning to previously identified locations to record vocalizations. They also found the Fulvous Owl (Strix Fulvescens) in Oaxaca Mexico, a relative that is more common in Mexico and Central America but has a much larger range.Proposal 2021A-3: Splitting Mew Gull into Common Gull, and Short-billed GullChesser quips that "if you're a coast-to-coast aviator, you might be able to find a new species this year." He is referring to the splitting of Mew Gull, Larus canus, into two species: Common Gull, (Larus brachyrhynchus) and Short-billed Gull, the names used for this species since the very beginning of the Check-list, 1886. Common Gull breeds and travels around Eurasia, Canada and Alaska. The Short-billed Gull is found in the northwestern United States and spends its winters along the Pacific coast, as well as the interior, mainly in the western U.S. The split is based on differences in display vocalizations, but also genetic and other morphological differences. This proposal was made by Pamela C. Rasmussen (Michigan State University), a member of NACC. These species were lumped together based on weak evidence from a 1919 paper.Splitting of Grass Wren and Sedge Wren (Proposal 2021C-3)According to Chesser who wrote a proposal to split the species, Chesser believes that previous ideas about how Sedge Worm (Cistothorus platesnsis), should be broken down. This proposal was based partly on an earlier proposal to South American Classification Committee. The 1998 Check-list stated that Sedge Wren was a single species, with its range extending from Canada to South America. It included three distinct groups: the stellaris group, which covered Canada and Panama, as well as two other South American groups, the platensis (and polyglottus) groups. The species split is not based on vocalizations or genetics. It does not happen where we expected. This is based upon what we know about intraspecific variation within the species. It turns out that the U.S. and Canadian populations are different from all the other populations, including those in Mexico, Central America and South America. Therefore, they are being separated from the rest. Because of priority reasons, the southern species, Grass Wren, will be kept as the scientific name, while the northern species, Sedge Wren (Cistothorus stardus), will keep its English name. After having considered the separate proposal, the SACC had made this split before.Transfers between GeneraA new (old) genus for the Ruby-crowned Kinglet. (Proposal 2021–A-9)The Ruby-crowned Kinglet (Regulus Calendula, now Corthylio Calendula) is a small, olive-colored songbird that breeds in forests throughout the United States and Canada. It has a bright red crown, but it's hard to see in males. It is one of six species belonging to the Regulidae family, which are all currently placed under the same genus Regulus. There are two species in the New World: the Ruby-crowned Kinglet and the Golden-crowned Kinglet. Four species can be found in the Old World. These include the Firecrest (Regulus ignicapilla), and the Goldcrest (Regulus ululus). The 1931 AOU Check-list had the Ruby-crowned Kinglet transferred to Corthylio as it was a result of morphological differences to other species. However, it was returned back to Regulus in 1957 with Corthylio being relegated from subgenus status and has been kept in Regulus since."It is well-known that the Ruby-crowned Kinglet is markedly different from other regulids in plumage, and other aspects, and this was reflected in the fact that the genus Corthylio Cabanis (1853) was erected to this species," Natalia C. Garca and Pamela C. Rasmussen, NACC member (Michigan State University), state in their proposal. Moreover, vocal and genetic data including molecular genomics studies that date back to the early days molecular systems, as well as molecular analyses, have repeatedly shown that the Ruby Crowned Kinglet is quite different from any other species in Regulus.Chesser says that this is his favorite proposal for the year. He also notes that it will be of interest to birders because they will enjoy the same benefits. This will help me to appreciate an unassuming bird that is both evolutionaryly fascinating and very different from other members of its family.Revision of Linear SequenceRevision of the Linear Sequence for Passerine Families (Proposal 2020-B-7)Chesser and Shawn Billerman, NACC members, proposed a revision and update of the linear sequence of passerine family to better reflect their phylogenetic relationships. Chesser says, "This is a major step forward that reflects the wealth of new information about evolutionary relationships among passerine family," Although this revision may cause some short-term disturbance, we believe it will be offset by the benefits of a more scientifically precise classification that should remain stable in the future with minor adjustments. We were convinced that this revision was necessary because several genomic studies had produced almost the same phylogeny.About the JournalOrnithology, formerly known as The Auk: Ornithological Advances, is an international peer-reviewed journal of ornithology that is published by The American Ornithological Society. In January 2021, the journal's name was changed to Ornithology. Ornithology was first published in 1884. In 2009, it was named one of the 100 most influential journals in biology and medicine in the past 100 years.###
