Birder's Guide

OCT 2017

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 38 of 51

37 October 2017 | Birder's Guide to Listing & Taxonomy Goodbye to Thayer's Gull –––––––––––––––––––––––––––––––––– • Larus thayeri ➛ Larus glaucoides thayeri Thayer's Gull is now treated as a subspe- cies of Iceland Gull. The authors of the Supplement state that more research is needed to determine if kumlieni should still be maintained as a valid subspecies; many birders and scientists believe it is instead a hybrid swarm between L. g. glaucoides and L. g. thayeri. Whatever you believe, your ABA Area list just decreased by one if you've seen both. Unfortunately, this lump breaks the NACC's own "A=B+C Rule", which states that unique English names should be used for splits and lumps so as to avoid confu- sion. When someone shouts "Iceland Gull" at the lake watch this winter, what does it which it shares its range— but it also has different vo- calizations. It seems that the evolution of Cassia Crossbill is a rare example of sympatric speciation in birds. Good locations for seeking this species in the South Hills of south-central Idaho in- clude Wahlstrom Hollow, Lower Penstemon Camp- ground, Pettit Campground, the Diamondfield Jack park- ing area, and the Bostetter Guard Station. All are eBird hotspots. Separation of Cassia Crossbill from Red Crossbill is challenging, to say the least. Photos and audio record- ings are certainly helpful, but note the fol- lowing: Cassia Crossbill's songs are more complex than those of Red Crossbill. Its dyup call has been described as dry, hol- low, noticeably lower-pitched, and dull- er-sounding than the jip! of "Type 2" Red Crossbill; it may even recall the chup of an agitated American Robin. Cassia Crossbill's bill is shorter and thicker than those of the Red Crossbill "types" in the area. For more on Cassia Cross-bill, check out crossbill. Finally, the Idaho Press Club lists CASH-uh (such as in the middle two words of "to cash a check") as the preferred pro- nunciation of the county and, thus, the bird. mean? Does the speaker intend a purely white-winged bird (glaucoides sensu stricto), as I would? L. g. glaucoides or L. g. kumlieni? Or glaucoides, kumlieni, or thayeri? It seems that Baffin Gull, Arctic Gull, Inuit Gull, Green-billed Gull, and Silver-winged Gull could have been workable and confusion- saving alternatives for naming the more- inclusive taxon. Split of Magnificent Hummingbird –––––––––––––––––––––––––––––––––– • Rivoli's Hummingbird (Eugenes fulgens) • Talamanca Hummingbird* (Eugenes spectabilis) This split separates birds of southern Central America from those of the U.S. and northern Middle America. Rivoli's Hummingbird is found in pine-oak wood- lands from the southwestern U.S. south to northern Nicaragua; adult males have a peridot-colored (yellow-green) throat and blackish underparts. Talamanca Hummingbird is found in cloudforest and high oak forests of Costa Rica and western Panama; adult males have a turquoise- or teal-colored throat and dark green un- derparts. The latter was originally named Michael L. P. Retter Fort Worth, Texas An adult nominate Iceland Gull ( Larus glaucoides glaucoides ) from the Shetlands Islands north of Scotland. Photo © Hugh Harrop - Shetland Wildlife An adult "Thayer's" Iceland Gull ( Larus glaucoides thayeri ) from Illinois. Note that many Thayer's have pale eyes. Photo © Amar Ayyash An adult "Kumlien's" Iceland Gull ( Larus glaucoides kumlieni ) from Illinois. Photo © Amar Ayyash A female Cassia Crossbill uses its unique bill to open a lodgepole pinecone and extract a seed with its tongue. Photo © Craig Benkman

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