[obol] Re: Black Butte Swamp thrush question
- From: Wayne Hoffman <whoffman@xxxxxxxx>
- To: David Irons <llsdirons@xxxxxxx>
- Date: Tue, 3 Jun 2014 09:48:24 -0700
Hi -
I agree with Dave in just about everything he said. A little more info on
3 points:
1. There are in fact serious rumblings about splitting Swainson's
Thrushes. A few years ago a graduate student in California (I think
Berkeley but may have misremembered) studied thrushes in the high Sierras,
and found overlap or near overlap without interbreeding. She wrote that
they appeared to be acting as separate species, but that "more study was
needed." I am anticipating seeing more on this in the near future. If we
did find areas with both in Oregon (e.g. east slope of the Cascades?) they
might be very informative.
2. In Oregon, as Dave stated, Townsend's/Hermit Warblers as breeding birds
act as an east-west pair, with Townsends basically from the east side of
the Cascades in Central Oregon east through the Ochocos and Blue Mts. into
the northern Rockies. However, in Washington, it's a north-south
phenomenon, with Townsend's to the north of Hermits both in the Olympics
and the Cascades. If I remember correctly, Townsends breed right out to
the coast in British Columbia, so they have a much broader habitat
tolerance.
3. I have not learned how to distinguish the kinds of White-breasted
Nuthatches. I have photos from Cabin Lake which I assumed are tenuissima.
When I see Steve Mlodinow's article I'll try to verify that.
Wayne
On Tue, Jun 3, 2014 at 1:25 AM, David Irons <llsdirons@xxxxxxx> wrote:
> Steve at al.,
>
> As Wayne Hoffman wrote earlier, sorting out Swainson's Thrushes is not too
> hard given a decent view. Birds of both the Russet-backed and Olive-backed
> groups occur in Oregon, with Russet-backed being the expected form from at
> least the crest of the Cascades west to the Pacific Ocean. If you look at
> the Oregon Breeding Bird Atlas (BBA) map for Swainson's Thrush in Birds of
> Oregon: A General Reference (BOGR), you'll notice that there is a
> significant gap in the distribution of breeding Swainson's in Oregon.
> Western Oregon (the area west of the Cascades) is blanketed with hexagons
> where summering Swainson's were recorded, with that blanket extending
> across the Cascades crest into the westernmost reaches (higher wetter
> slopes) of the four eastside counties that abut the Cascades (Wasco,
> Jefferson, Deschutes, and Klamath). Then there is a rather spotty
> distribution of hexagons where breeding season Swainson's were recorded
> (during the 1995-1999 surveys) until you get over into the Blue and Wallowa
> Mtns, where there is a pretty solid blanket of detections. Unfortunately,
> the BOGR account doesn't really address which type occurs in the Blues and
> Wallowas and perhaps the Ochoco Mtns from looking at the map, but I'm
> presuming that these are Olive-backed birds. I agree with Wayne's
> suggestion that the birds you saw were probably of the Pacific Coastal
> Russet-backed group.
>
> It is certainly worth paying close attention to Swainson's Thrushes when
> you see them, particularly those found east of the Cascades crest.
> Olive-backed birds were recently discovered breeding west of the Cascades
> crest in nw. Washington and it may be that there are some areas along the
> crest of the Oregon Cascades where both types can be found. Some of these
> questions have received very little if any study aside from specimen
> review. With a decent digital camera and some focused effort any of us can
> endeavor to answer such questions. I just spent much of the past weekend
> birding in southern Morrow County, which extends into the westernmost
> section of the Blue Mountains. We saw and heard no Swainson's Thrushes,
> despite being in habitats that seemed reasonably suitable for this species.
> More surprisingly, we saw and heard no Hermit Thrushes either. Our only
> *Catharus
> *thrush of the weekend was a Veery that we found right in the town of
> Lexington. On Friday, Jim Danzenbaker, who was traveling with us, saw an
> Olive-backed Swainson's Thrush at Deschutes River State Park in Sherman
> County. I tried to relocate the bird, but never saw it.
>
> As for White-breasted Nuthatches, birds found in the Willamette, Umpqua,
> and Rogue Valleys are generally assigned to the subspecies *aculeata*.
> Steve Mlodinow, who is currently working on an article about the
> identification and distribution of western White-breasted Nuthatches told
> me recently that the birds in extreme western Klamath County (where there
> are some oaks) are also *aculeata. *Birds that I photographed last year
> at Running Y Ranch do appear to best fit *aculeata. *Generally, birds
> found east of the Cascades have been assigned to the subspecies
> *tenuissima*, but if *aculeata *is found east of the Cascades in Klamath
> it may not be safe to presume that birds in western Deschutes Co. are
> *tenuissima.
> *I photographed a White-breasted in southern Morrow Co. over the weekend
> and I am anxious to take a closer look at those photos to see if that bird
> can be assigned to subspecies.
>
> The Cascades are an intriguing zone of contact for many species and
> subspecies pairs whose ranges tend to be defined by a wet slope-dry slope
> division. The obvious poster children in this regard are the Hermit
> Warbler/Townsend's Warbler and Red-naped Sapsucker/Red-naped Sapsucker
> pairs. We tend to pay closer attention when full species are involved, but
> some of the subspecies pairs are equally intriguing. There seems to be an
> imminent split of the White-breasted Nuthatches on the horizon and I've
> heard some lesser rumblings about splitting the Olive-backed and
> Russet-backed Swainson's Thrushes into two species. Sorting the nuthatches
> takes a practiced eye, but separating the two Swainson's Thrush groups is
> not particularly challenging.
>
> If you look at the BirdFellow ID gallery at the link below, the first two
> images were both taken in Oregon. The first, is a Olive-backed migrant that
> I photographed at Malheur HQ during Memorial Day Weekend a couple years
> ago. The second is a Russet-backed bird that I photographed at Grand
> Island, Yamhill County.
>
>
>
> http://www.birdfellow.com/birds/swainsons-thrush-catharus-ustulatus#/idPhotos
>
>
> Dave Irons
> Portland, OR
> ------------------------------
> From: sbkornfeld@xxxxxxx
> To: obol@xxxxxxxxxxxxx; cobol@xxxxxxxxxxxxxxxxxxxxx
>
> Subject: [obol] Black Butte Swamp thrush question
> Date: Mon, 2 Jun 2014 18:11:14 -0700
>
>
> Greetings.
>
> Birded the Black Butte swamp this am coming in from the Glaze Meadow
> side. Very active with abundant vireos, flycatchers, warblers and
> woodpeckers. My hope was Veery with previous reports from years past. No
> luck with Veery.
>
> Swainson's Thrush were scattered in the swamp. Hoping to sort out
> Interior West versus Pacific. Are these Swainson's spill overs from the
> other side of the Cascades or part of the interior west population?
> Similar question to White-breasted Nuthatch and a few others.
>
> thanks
>
> Steve Kornfeld
> Bend
>
>
>
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