Birder's Guide

OCT 2014

Birder's Guide is the American Birding Association's newest publication. Each issue focuses on a key subject, providing tips from experienced birders on a wide variety of topics like Travel, Listing & Taxonomy, Gear, and Conservation & Community.

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Page 21 of 57

Species & Subspecies 20 Birder's Guide to Listing and Taxonomy | October 2014 irders throughout the ABA Area wait in anticipation every summer for the latest changes in the American Ornithologists' Union's (AOU's) Check-list of North American Birds. These updates are automatically accepted by both the ABA and Clements checklists, and splits of cur- rently recognized species result in "armchair ticks", added entries on birders' life lists that require no additional effort. Older birders may remember that checklist changes were not al- ways a source of happiness. Perhaps the most infamous checklist update occurred in 1973. It resulted in the downgrading of numerous species into subspecies, leading to the loss of Great White Heron, Eurasian Green-winged Teal, Harlan's Hawk, two species of ficker, Black- eared Bushtit, Audubon's Warbler, Bullock's Oriole, Ipswich Sparrow, two species of Seaside Sparrow, and three species of junco. Since 1973, some of these birds have been re- turned to full species status (e.g., Gilded Flicker, Bullock's Oriole), while others have been subject to recent checklist change proposals which did not pass (e.g., Yellow-rumped Warbler). Today, there are often debates over whether a species should be recognized, with recent confict over birds such as Fox Sparrows and crossbills. Much of the change in how we recognize what constitutes a species has come about due to new technology such as gene sequencing or analytical analyses of plumage and vocalizations. But much of the debate over recogni- tion of species actually stems from changes in how we think about what a species is. Of course, a species is not just a tick on a check- list. It's a basic unit used by biologists, conservation- ists, and policy makers to identify a group of organ- isms. Because of this, how we classify species can have major consequences on regulation and conser- vation. Changes in how species are recognized can lead to differences in how we recognize where bio- diversity hotspots are located (Agapow et al. 2004; Isaac et al. 2004) and can infuence population monitoring, allocation of resources, and funding for conservation (Daugherty et al. 1990; Sangster 2000; Isaac et al. 2004; Zink 2004; Johnson et al. 2005; Rising 2005). This means that the criteria we use to recognize species are not merely an esoteric concern of scientists, but have real-world implica- tions for the birds themselves. In this article, I give a brief history of how scien- tists, and specifcally ornithologists, have looked at species concepts; I also provide an (incomplete) overview of the challenges and future directions in defning bird species. At present, more than 22 species concepts have been named (Mayden 1997); however, many of these have not been widely ad- opted or were focused on problems that ornitholo- gists thankfully don't have to deal with (like species which reproduce asexually). For that reason, I limit this discussion to a few commonly cited species concepts relevant to bird speciation. Origins of Classifcation The concept of "a species" was frst introduced by Carl Linnaeus, the father of taxonomy, in 1735, in the work Systema Naturae (Linnaeus 1735). His greatest innovation was the creation of the binomial system (Genus species) for referencing organisms. B Species & Subspecies Species & Subspecies A Brief HisTOry Editor's Note: Many birders are interested in taxonomic changes, because they can impact conservation pro- grams and because they can result in species being added or removed from checklists. But it can be diffcult to understand why some changes are made and why scientists so fercely argue about whether something is a species or "just" a subspecies. This article lays out the basics of how ornithologists defne species and subspecies and offers insight into how our knowledge of what a species is has changed and been challenged in recent years. Carl Linnaeus is widely considered the father of taxonomy. He invented the binomial nomencla- ture ( Genus species ) that we still use today. image © Alexander roslin

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