Date: 3/30/17 10:28 pm
From: David Irons <LLSDIRONS...>
Subject: [obol] Re: BREAKING NEWS
Wayne et al.,


It is likely that the eastern form of Nashville Warbler has already been seen in Oregon, perhaps many times. A Nashville Warbler or two are found every winter in Oregon. These birds tend to show up in November or later, roughly two months after fall migrant Nashvilles have evacuated the state. This big break between typically departure dates and the appearance of overwintering birds suggests that the latter may not originate from proximal breeding populations.


There is another factor that supports this idea in my opinion. Many of the wintering birds we see do not seem to wag their tails nearly as much those that we see during spring migration and on their Oregon breeding grounds. The western population birds are vigorous tail-waggers and flip their tails almost constantly if you spend much time watching them. Many sources indicate that tail-wagging is much reduced in eastern birds. There was some discussion of this more than a decade ago when Mark "Rudi" Rudolph had a Nashville wintering in his N. Eugene yard (2003 as I recall). He noted that the bird was not wagging its tail, which gave rise to curiosity about whether it might be an eastern bird. I went and saw the bird and watched it come to his suet feeder several times over about an hour. I only saw it flip its tail a couple of times.


A few years later (in early September 2008) Steve Mlodinow and I saw a Nashville Warbler in eastern Washington that we suspected was of the eastern subspecies. It barely wagged its tail and it appeared to be more rich yellow below. We did not get any photos. I'm not sure how useful the described color differences are. Greens and yellows tend to vary in intensity depending on light conditions and viewing angle. Of course age and sex contribute to this variation as well.


It should be noted that the breeding range of western Nashvilles is fairly constrained and they are also comparatively early fall migrants. They breed on drier mid-elevation (2500-5000') slopes on both sides of the Cascades and in the Sierra Nevada, with the nesting range extending only as far north as south-central British Columbia. They also nest in the Siskiyou and Trinity Mtns. in SW Oregon and NW California and they nest in the east-facing foothills of the Oregon Coast Range (common west of Roseburg) with that branch of the range essentially petering out southwest of Eugene. A singing male Nashville near Lorane during June is the northwestern most territorial bird that I've found in Oregon. As I recall, Doug Robinson found a territorial Nashville in SW Benton Co. within the past couple years. Perhaps Tom Mickel, who spent many years working in the Coast Range, can offer more clarity on the status of Nashvilles in the Lane County Coast Range.


As mentioned above, western Nashvilles migrate south pretty early. When I was spending lots of time there in the late 80's and 90's Nashvilles were common on and around my ex-inlaws property west of Melrose in Douglas County–about 15 miles out of Roseburg. They were readily detectable there May-July, but would typically be gone by mid-August. They are hard to come by anywhere in Oregon after early September. They are remarkably rare fall migrants through the lowlands of northwestern Oregon. Offhand I can't recall ever seeing a lowland westside migrant during September and yet I've probably seen about 15-20 winter birds in western Oregon. The eastern population has a far more expansive breeding range that extends much farther north (in terms of latitude) than the northernmost breeding outpost of the western population. I don't know what the estimated numbers are for the eastern and western populations, but based on the size of their respective breeding ranges, I would expect that eastern birds outnumber western birds.


It would be great to unravel the mystery as it relates to the origin of wintering Nashvilles in Oregon, but without grabbing some DNA I'm not sure how you would go about it.


Dave Irons




________________________________
From: <obol-bounce...> <obol-bounce...> on behalf of Wayne Hoffman <whoffman...>
Sent: Friday, March 31, 2017 2:34 AM
To: Lars Per Norgren; Joel Geier
Cc: <obol...>
Subject: [obol] Re: BREAKING NEWS

Hi -

I think the eastern form is a likely vagrant to Oregon, so it would be good for us to brush up on how to tell them apart. According to the Dunn and Garrett warbler guide, eastern bird have greener backs, and underparts not so bright yellow but more extensive (western have more white around the vent). Songs are distinguishable, but we may be likely to get non-singing migrants.

Wayne

On 3/30/2017 6:46:37 PM, Lars Per Norgren <larspernorgren...> wrote:

_

I recall rumblings of the Nashville Warbler split about ten years ago. Gabrielson and Jewett had the subspecies "Calaveras Warbler" in Birds of Oregon. I believe the Mark Twain short story was titled "The Celebrated Jumping Frog of Calavereas County."
On Mar 30, 2017, at 4:17 PM, Joel Geier wrote:

> Hi all,
>
> Thanks Mike for posting the list of proposals. It's fascinating that all
> of the discussion here on OBOL so far has focused on gulls.
>
> I was personally most intrigued by Ralph Browning's proposal to split
> Nashville Warbler into Calaveras" Warbler and Rusty-capped" Warbler, and
> his dry comment on the latter, "Although the name does not differentiate
> it from some other species, the name Nashville is even less useful."
>
> For sheer fussiness, it's hard to top the proposal to change Le Conte's
> Sparrow and Thrasher to LeConte's Sparrow and Thrasher, respectively.
> This is surely the most momentous proposal to come before the committee
> since the one that gave us Harris's Sparrow in place of Harris' Sparrow.
>
> Anyway this certainly added to the enjoyment of listening to a Nearctic
> Creeper as it sang at Luckiamute State Natural Area this afternoon.
>
> Happy birding,
> Joel
>
> --
> Joel Geier
> Camp Adair area north of Corvallis
>
>
>
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