Re: [SBB] yard Swainson's (?) Thrush (drama, pic)

["Alvaro Jaramillo" <[[email protected]]>]

Tom

   This is a weird looking Swainson's Thrush, the weird part is how grayish
it looks on the head. In addition, it is not all that warm colored on the
upperparts as on our typical Swainson's Thrushes here. It also looks really
extensively marked below, something more typical of Hermit, but it could be
the way the flanks are being fluffed and the angle of the photo. The buffy
flanks are a good way to separate between dull Hermits and Swainson's, other
than features you mentioned. Western Hermits have grayish flanks. 
	The grayish head and general color makes me wonder if this is not a
more eastern subspecies (what was once called the Olive-backed Thrush).
There is a form, incanus, from the western portion of the range which is
typified by being grayish. I have banded these in the Okanagan in British
Columbia, where presumably they reach their greyest extent and was surprised
at how little warm wash they showed in the spectacles and throat. Now given
the large range of this form, and the fact that it has been thought to be
dubiously distinct, it likely varies a lot. But since your bird looks so
"off" from typical "Russet-backed" Swainson's, it makes me think it is one
of these incanus. Here is what the Birds of North America had to say about
this form: 

C. u. incanus (Godfrey, 1951): Type specimen Yukon. Breeds central and e.
Alaska, s. Yukon, n. British Columbia, and n.-central Alberta. Winters
Colombia south to Peru. Most similar to swainsoni but with more rufous tail,
grayer above, paler buffy areas of head, and less buffy coverts and edges of
remiges. Grayer below than ustulatus, with darker and denser
breast-spotting. Although considered a questionable race by M. A. Ramos (in
Phillips 1991), review by Gibson and Kessel (1997) recognized incanus as
valid. Also note this is an “Olive-backed Thrush” despite inclusion in
russet-backed group by Pyle (1997).

Cheers

Al

Alvaro Jaramillo
[[email protected]]
Half Moon Bay, CA

Field Guides - Birding Tours Worldwide
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> -----Original Message-----
> From: [[email protected]] [mailto:south-bay-birds-
> [[email protected]]] On Behalf Of Tom Grey
> Sent: Sunday, October 01, 2006 12:49 PM
> To: [[email protected]]
> Subject: [SBB] yard Swainson's (?) Thrush (drama, pic)
> 
> My wife called me when she noticed this little critter sitting, apparently
> stunned, on the deck outside our kitchen sliding glass door shortly before
> noon.
> 
>  http://www.pbase.com/tgrey/image/67831155
> 
> Happy ending! I grabbed the camera and crept around to get a profile view,
> got this shot and a couple of others, and then when I moved to get a lower
> angle,  the bird flew off, apparently recovered.
> 
> Anyway, it is a departing SWAINSON'S, isn't it (brown tail, strong
> spectacles) and not possibly an especially drab arriving Hermit, in which
> case I would have to say Catharus sp? You can tell where my preferences
> lie
> -- I have Hermit photos in my collection but no Swainson's yet. (The color
> should be pretty accurate, allowing for cold light from the overcast --
> the
> weathered deck is like a gray card, and allows me to confirm correct white
> balance.)
> 
> **********
> 
> On that picture I posted of the juvenile tern from last weekend --
> http://www.pbase.com/tgrey/image/67709765 -- I've had the suggestion from
> one knowledgeable observer that, while it is certainly not a Forster's, it
> might well (by virtue of the short bill) be an Arctic rather than a
> Common.
> It seems to have a Common-ish dark leading edge to its far wing, but that
> could be a shadow or other photo artifact.
> 
> Tom Grey
> 
> 
> 
> 
> 
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