Birder's Guide

OCT 2016

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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TABLE 1 • Key to understanding how to read Table 2. Morphology: (√)= minor differences in size and/or structure; (+)= moderate to significant differences in size and/or structure Vocalizations: (√)= minor differences in song and/or calls; (+)= moderate to significant differences in song and/or calls Plumage and Bare Parts: (√)= minor differences in color and pattern; (+)= moderate to significant differences in color and pattern size and shape Ecology and Behavior: (√)= differences in habitat, foraging, breeding, migration, molt strategy, and/or courtship Level of Hybridization: (-)= broad hybrid zone; (√)= narrow hybrid zone Genetic Divergence: (√)= detected in mitochondrial and/or nuclear DNA (*)= differences anecdotal, conflicting evidence, or in need of more study (X) = extralimital (not recorded in the ABA Area); (V) = generally a vagrant to the ABA Area 25 October 2016 | Birder's Guide to Listing & Taxonomy ther studies are being conducted on all of these, however, so don't erase those check- marks just yet! In summary, nearly all of these forms may be identified in the field (see Sibley, 2012) and should be of interest to bird- ers. There's a whole fascinating taxonomic world beyond the current ABA Checklist, and—who knows?—maybe someday that "Cape Sable" Seaside Sparrow you saw in Everglades National Park will give you an armchair tick. I encourage you to pursue and enjoy all of these identifiable forms! ––––––––––––––––––––––––––––––––– Editor's Note: References noted in this article and an appendix covering extra- limital splits and lumps are available in an expanded, online-only version of this article, which you may view at tinyurl.com/Knue2016. or only minor divergence between popu- lations, that means they should remain a single species or be lumped. Proposed changes indicating that moderate or sig- nificant divergence has occurred suggest that more than one species could be rec- ognized. In some cases, a missing code indicates a lack of evidence or that more research is needed. If I had to make predictions, I suspect the next 10 splits would involve Mallard, Spruce Grouse, Northern Fulmar, Willet, Warbling Vireo, White-breasted Nuthatch, Marsh Wren, Yellow-rumped Warbler, Savannah Sparrow, and Fox Sparrow. As for lumps, the species pairs on this list with weak support as separate species are Pacific-slope and Cordilleran flycatch- ers, American and Northwestern crows, and Common and Hoary redpolls. Fur- tive, including differences in molt timing, breeding behavior, courtship, and mo- lecular structure, and these are indicated where evidence exists. Tobias et al. (2010) went further, providing a system of criteria around their characteristics whereby spe- cies pairs could be evaluated and scored. The resulting score is then used to deter- mine whether the related forms should be recognized as separate species. Although some taxonomic authorities (del Hoyo and Collar, 2014) are using this scoring system to make taxonomic decisions, this practice remains controversial (Remsen, 2015). It is beyond the scope of this account to delve that deeply. References, many of which present im- portant genetic research, are provided for most species in the expanded online ver- sion of this article. The reference list is not exhaustive but, rather, representative of the most recent or important work pub- lished. Refer to the Handbook of the Birds of the World (or HBW Alive) and Cornell Lab of Ornithology's Birds of North America On- line for descriptions and characterizations of measurements, plumage, vocalizations, and ecology. Table 2 can be used as a guide to under- stand whether there is evidence to support separate- or same-species status for a given species pair or species group. Generally, when there is no evidence of differences n "Franklin's" Spruce Grouse. Photo © Chris Peterson n "Haida Gwaii" Northern Saw-whet Owl. Photo © Greg Lavaty

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