Date: 7/5/20 2:10 pm
From: Tom Crabtree <tc...>
Subject: [obol] Re: Lake County PAC-slope?

It trips rare because the default is Pacific-slope x Cordilleran (Western) Flycatcher for Lake County. Photos won’t do you any good for the species. Someone who has studied them for years indicates that he doubts any birds North of Arizona/New Mexico are pure birds, there is a lot of admixing going on. I have heard birds in Bend alternate Pac-slope and Cordilleran calls. I had one this summer that started with a Cordilleran note and then go into full Pac-slope mode.

An article published last year [Linck, E., K. Epperly, P. van Else, G. M.. Spellman, R. W. Bryson, Jr., J. E. McCormacks, R. Canales-Del Castillo, and J. Klicka. 2019. Dense geographic and genomic sampling reveals paraphyly and a cryptic lineage in a classic sibling species complex. Syst. Biol. 0(0):1–11, 2019, DOI:10.1093/sysbio/syz027.] posits that there anywhere between one and four species involved in this complex. They favor either one species for all of Western North America (including hybrids) or two species split with one for the US and one for Mexico. Either would eliminate the Pacific-slope/Cordilleran conundrum that we deal with here. [As an aside, if you want to see a really funny interpretation, look at the eBird maps for Cordilleran and Pacific-slope Flycatchers along the Washington/Idaho border. It’s amazing how those birds can read maps!] The authors acknowledge that a different definition of what is a species could lead to four different species, but don’t resolve that question and say “a detailed analysis of these data will be presented elsewhere.”

Here is a map showing the information their data shows the following. [Gray dots are Pacific-slope, yellow are Cordilleran and the orange and green are the Mexican forms. Where a dot has two colors it shows the intermixing of the forms. Unfortunately they didn’t examine any Central Oregon birds.

It appears we haven’t heard the last word on Empidonax difficilis (difficilis indeed!).


Tom Crabtree, Bend

From: <obol-bounce...> [mailto:<obol-bounce...>] On Behalf Of Jack Maynard
Sent: Sunday, July 05, 2020 12:35 PM
To: Oregon Birders On Line
Subject: [obol] Lake County PAC-slope?

Hello obol,

With some trepidation I am going to check in a Pacific-slope Flycatcher from a location SE of Lakeview in The Warner Mountains. It trips Rare. I have a few pics and a sound recording but very limited connectivity here.

Kelli and I were birding a spot called Willow Creek campground this morning and heard what we thought were the distinct vocalizations of the Pac-slope, but thought they shouldn’t be present this far East. We heard at least two birds making the Ju-weeeep call and eventually saw two and photographed one of the birds. I’ll include a pic or two with this email. I won’t be able to get the sound recording uploaded until I get home to Portland tomorrow or Tuesday.

I’ll be interested to hear from folks as to whether this was a good ID. Both pac-slope and Cordilleran tick rare. West of the cascades I’d call these pacific-slope and move on.

Sorry about the blurry photos, they are the only ones I could get to transfer from my camera.

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