Birder's Guide

NOV 2013

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 42 of 67

Comments In recent decades, the practice of collecting birds to document frst state, provincial, or national records in the ABA Area has nearly ceased. Birders and feld ornithologists with digital cameras—increasingly on their smartphones—routinely document rare birds and post the images online, usually within hours of the sighting. Bird banders now sometimes take blood samples and pluck feathers before releasing the birds they band; these may be used for subsequent DNA analyses and stable isotope analyses. The latter allow for an approximate determination of where birds were geographically several months to a year prior to the date of capture. Other evidence can be obtained from fecal samples or from feathers shed by birds that were never captured. A compelling case study involves a murrelet found dead in New Mexico in 2009; the bird could not be identifed by traditional morphometric and plumage characters, but DNA analysis confrmed that it was New Mexico's frst Long-billed Murrelet (Witt et al. 2010). In the case of the Alaska moorhen, photographic evidence would not have been defnitive to species, and capture with a mist net or other means was probably not feasible. The collecting of birds will probably continue to play a role in ornithology in the ABA Area, but at only a shadow of its importance 150 years ago. Some of the reasons for the decline of scientifc collecting may be waning public support for the practice, coupled with increasing urbanization that precludes discharge of shotguns. But just as important is that diagnostic DNA analysis doesn't require a traditional specimen; a feather or a small blood sample is suffcient. Stray hummingbirds are increasingly identifed by molecular analysis of their feathers, and potential vagrant skuas to Britain have been identifed by their mitochondrial DNA (see Hess 2004). Fascinatingly, genetic analysis sometimes results in conclusions that are substantially different from speculations based on analysis of high-quality digital photographs. A good example of this is an extremely well-studied and well-photographed hummingbird in Illinois in 2011 that was believed to be a Broad-tailed Hummingbird by some observers; DNA analysis, however, showed that it was at least 75% if not 100% Rufous Hummingbird (Swick 2011). Finally, we note that there is increasing support for—but also a lot of opposition to—the scientifc description of bird species new to science based not on a "type specimen" but rather only on small tissue samples; Peterson and Lanyon (1992), in an early commentary, well anticipated much of the current debate. Common Chiffchaff (Phylloscopus collybita) –––––––––––––––––––––––––––––––––– Background One individual at Gambell, St. Lawrence Island, Alaska 6–7 June 2012 was extensively photographed (Lehman and Zimmer 2013). Although consensus was not initially achieved—with some considering the bird to be a Willow Warbler or some other Phylloscopus—the short primary projection and the dark legs and feet led many to believe that the bird was a Common Chiffchaff. Subsequent and detailed analysis of the photographs confrmed the identifcation by the presence of four emarginated primaries (rather than three on Willow Warbler). Identifcation as the Siberian subspecies tristis was based on geography and strongly suggested by the dull plumage and rather strong supercilium. Comments The Gambell chiffchaff well illustrates how far the "digital revolution" has come. As recently as 25 years ago, bird photography was practiced by only a handful of photographers—mostly professionals or semiprofessionals—with ample time, money, patience, and skill, who lugged around big, heavy telephoto lenses on giant tripods. Although photographers with giant lenses are an increasingly common sight at rare-bird chases today, many "serious" birders carry into the feld small digital cameras with surprisingly high resolution capabilities. Even an inexpensive pointand-shoot digital camera (costing much less than most binoculars) can instantly Common Moorhen. United Kingdom. Photo © Christopher Taylor. November 2013 | Birder's Guide to Listing & Taxonomy 41

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