Date: 7/31/19 11:01 am
From: <clearwater...>
Subject: [obol] Re: American or Eurasian Three-toed Woodpeckers -- how can we be sure?
Hi Nagi,

Sorry, I was being facetious, but that might not have been fully clear.

To my knowledge, the Eurasian and American species of 3-toed Woodpecker are practically indistinguishable based on plumage. The split between species is based on genetic differences is based on genetic work by Robert M. Zink and coauthors, "Trans-Beringia comparisons of mitochondrial DNA differentiation in birds," published in The Condor , vol. 97 p. 639-649. The same paper also contributed to the split between our (North American) Black-billed Magpie and their Eurasian counterparts, and Wilson's vs. (Eurasian) Common Snipe.

My aim in this posting was to illustrate how often we rely on range maps in our identifications.

Congrats on seeing your lifer American Three-Toed Woodpecker! I still haven't managed to see their Eurasian counterpart despite all of my time in Sweden & Finland.


From: "Nagi Aboulenein" <nagi.aboulenein...>
To: "Oregon Birders OnLine" <obol...>, "clearwater" <clearwater...>
Sent: Wednesday, July 31, 2019 10:25:09 AM
Subject: Re: [obol] American or Eurasian Three-toed Woodpeckers -- how can we be sure?

Hi Joel -

Having just seen our lifer American Three-toed Woodpecker in the Sisters area (Rooster Burn area, and, amusingly, we first mistook it for a Hairy Woodpecker, and only upon closer inspection of the photos a few days later did we realize what we had seen \uD83D\uDE0A ), I’m curious about field marks distinguishing ETWO (Eurasian) vs. ATWO (American)?

A quick online search (including in the Birds of North America) didn’t come up with much other than to mention the split.


On Jul 31, 2019, 08:43 -0700, <clearwater...>, wrote:

Here's another issue that I'd bet few Oregon birders have thought about:

How sure are we that the Three-toed Woodpeckers in the Oregon Cascades are American and not Eurasian Three-toed Woodpeckers? Is anyone checking field marks?

I mean sure, there was a scientific paper with genetic work to establish the split. But those specimens were at least a decade or two old. Is there any contemporary evidence?

I look forward to reading the arguments when the next OBOL digest lands in my inbox. Meanwhile, I'll go back to working on the project deadlines that Big Al summoned me forth from.

(And yes, this is meant to be ad absurdum).

Joel Geier
Camp Adair area north of the putative Blue-gray/California Gnatcatcher hybridization zone

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