North American Birds

VOLUME 69 No1 2016

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

Issue link: http://nab.aba.org/i/629070

Contents of this Issue

Navigation

Page 48 of 179

T H E C H A N G I N G S E A S O N S : O U T P O S T S emails. The other issue facing the reviewer is that bird species that make a quick leap from rarity to regular go quickly from receiving meticulous documentation to, well, almost none. The frst Cave Swallow gets four paragraphs of descrip - tion, but what happens when we see 200 in a represented in the mountain of reports? A new birder visiting a region can be forgiven his or her confusion when, on referring to the bar charts in eBird for a particular location, he or she is fum - moxed to learn that Falcated Duck appears to be locally "widespread" in this part of California! (Consultation of the map, individual checklists, and especially the different functions of the line graphs can help solve such riddles, but duplica - tion in the bar chart function makes some stake- out rarities appear disproportionately common.) But when a rare (review) species becomes rather suddenly and genuinely widespread, under - standing the new status—how many birds, when, and where—can be diffcult in an age of burgeoning data. We could consider this a good problem to have. To help editors and reviewers, birders contributing data to Project eBird should provide as much detail as possible on plumage and behavior but also precise information on lo - cation, so that the question of how-many-birds can be investigated without numerous follow-up fed by DNA analysis—of its excrement! Could any of us have imagined this scenario even 20 years ago? Birds captured at banding stations, such as several fne eastern Canadian records from fall 2014 (Figures 25-27), provide the most detailed and most reliable information on Empidonax distribution, but for most reports, we have neither morphometrics nor DNA. Some groups—such as the Empidonax and the mem - bers of the Solitary Vireo complex—are often diffcult to identify if one relies on just one or two posted photographs. The effects of lighting, exposure, and camera equipment can conspire to make each picture in a series look different from the next. An "obvious" Blue-headed Vireo in one frame looks like an equivocal Cassin's Vir - eo in another shot of the same bird taken just a few seconds later. We know in the past that pho - tographs of an Empidonax were enough to set off massive, unresolved debates on identifcation. Now that we'll be able to see many thousands of such images, do we risking opening a Pandora's box, to enter an Inferno of widespread discord? Pioneering (masochistic?) advanced birders push the envelope further still, into the iden - tifcation of subspecies, and autumn 2014 had many examples to consider. The Neah Bay Blue- gray Gnatcatcher was identifed as an Eastern; how many of us scrutinize vagrant (and those "late lingering") gnatcatchers this carefully? In eBird, feld-identifable subspecies can be add - ed to one's checklist, but we fnd new cans of worms for reviewers here. How many feld bird - ers can actually accurately identify many such individuals at the subspecies level? Was the Tex - as Bar-tailed Godwit in 2014 of the eastern Asian subspecies baueri? Or could it have been of the other Asian subspecies, menzbieri? Many observ - ers of the recent Virginia Black-tailed Godwit put it into eBird as being of subspecies island - ica, largely on the basis of geography. But de- tailed articles on identifcation of subspecies of Black-tailed (Roselaar and Gerritsen 1991, van Scheepen and Oreel 1995) do not provide frm support for identifcation as islandica. Some 160 kilometers off Humboldt County, California, an experienced observer saw a Eurasian Whimbrel 17 September 2014—but was it the (expected?) variegatus, or could it have been of the nominate subspecies? Or an even more obscure or contro - versial subspecies of Whimbrel? In our embarrassment of digital riches, other diffculties arise, not directly related to identifca - tion but to status. We are now so vigilant about reporting infuxes of rarities—think of Cave Swallows in the East, Blue-footed Boobies in the West, all widely chased by "m.ob."—that our reports overlap with reports of hundreds of oth - ers in the database that now includes thousands of data points. But how many actual birds are Figure 25 (top left). This hatch-year Dusky Flycatcher was pro- cessed by the Atlantic Bird Observatory on Bon Portage Island, Nova Scotia 6 October 2014. Measurements taken from this bird provided conclusive evidence for Nova Scotia's third record of this western Empidonax. Photograph by Avery Bartels. Figure 26 (top right). A hatch-year Hammond's Flycatcher at Bon Portage Island 30 September 2014 provided Nova Scotia with its second record. The frst was also caught, measured and banded by the Atlantic Bird Observatory on the island in 2013. Photograph by David Bell. Figure 27 (bottom). Furnishing just the fourth provincial record, this Gray Flycatcher was captured and banded at the tip of Long Point, Norfolk County, Ontario 29 September 2014 and seen by a few lucky observers the following day. Photograph by Dayna L. Leclair. V O L U M E 6 9 ( 2 0 1 5 ) • N U M B E R 1 47

Articles in this issue

Archives of this issue

view archives of North American Birds - VOLUME 69 No1 2016