Hi David et al,
Two questions I have- the early date and the clean white scapular edgings. Both mitigate against SBDO I think?
Ross
Ross Silcock
Seasonal Reports Compiler
Nebraska Bird Review
Co-Author Birds of Nebraska- Online
https://birds.outdoornebraska.gov/
From: cobirds@googlegroups.com <cobirds@googlegroups.com> On Behalf Of David Tønnessen
Sent: Thursday, April 15, 2021 10:53 PM
To: Colorado Birds <cobirds@googlegroups.com>
Subject: [cobirds] Short-billed Dowitcher, El Paso County
Hi all,
As Ted Floyd just touched here earlier this evening, the snow and dense low clouds today meant many northbound migrants were grounded in places they otherwise wouldn't stop or spend much time in. My forecasts indicate this could go on through tomorrow morning.
Anyway, this afternoon myself and a few other local birders photographed an apparent hendersoni (prairie-breeding) Short-billed Dowitcher at Squirrel Creek Reservoir, the first one I have seen in El Paso County. It took some close inspection and consultation with a couple individuals more experienced in visual dowitcher ID than myself including Alvaro Jaramillo, before I felt fully confident about the ID, hence the late posting. I believe the continued snow through tonight and through the morning may keep it in place through the night, however. If you want to learn how we came to the ID, read the next paragraph.
If you disregard the obvious plumage differences which are mainly the result of varying stages of molt, in the first photo below the Short-billed Dowitcher (center) is demonstrably a tad smaller, and clearly flatter-backed as a result of its folded tertial and primary feathers being held straighter than the two surrounding Long-billed Dowitchers. It is also not as front heavy, and the bill on this particular individual was shorter with a slight curve particularly notable when compared directly. As I understand it, the more spotted look to the undertail coverts as a result of thicker, ovate bands is also a good indicator for SBDO, and once this individual advances more fully into its breeding plumage it should show more spots centered at the shafts throughout the rest of the flanks. Long-billed have narrower bands more appropriately designated as barring. These nice photos were taken by Kevin Ash; note they appear very faded in color due to the lighting in the field.
Beyond shorebirds, passerine migration seems to be quite late this year, with only a slow trickle of migrant Yellow-rumped Warblers showing up in the state almost two weeks later than usual. I'd be intrigued to find out what's causing this, and if it has anything to do with the very cold and abnormally south-reaching vortex this last February. Or perhaps Bryan Guarente can enlighten us on other weather conditions happening in the Gulf that might be the cause.
Happy birding and ornithologizing,
David Tonnessen
CU Boulder
Colorado Springs
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