All

When I used to live on the California Channel Islands we would get hundreds
of SWTH in the pre-dawn, and then they were complete ghosts on the ground. I
mean, these things would simply disappear. It wasn't until I accidentally
found them one day that I finally realized what they were doing. Walking a
canyon bottom I flushed one out of a large cherry tree. Then a few more,
etc. Eventually there was a breaking wave of SWTH moving through the canyon
bottom ahead of me, but in the trees they were essentially undetectable. I
spent hours above on the cliffs trying to see one and never did. They must
simply stay very still and well-hidden. I don't fully understand it, I just
know that's what happens on the Channel Islands, where I heard tons and saw
very few--until I knew how to find them.

This of course doesn't mean they are in the interior west is huge numbers
too, I just thought I'd raise the visual detectability issue for this
species.

Brian

On Wed, Aug 26, 2009 at 2:21 AM, Ted Floyd <tfl...@aba.org> wrote:

>  Ah. Colby has brought up the strange case of the missing Swainson's
> Thrushes:
>
> > Interestingly, ZERO Swainson's Thrushes were heard.  Interestingly, in
> all my nights
> > listening (a couple dozen) in Utah, I never heard a Hermit or Swainson's
> Thrush in either
> > the spring or fall.  I don't know what these birds do between the
> Cascades/Sierras and
> > the Continental Divide given my experiences thus far as I'm certainly
> quite baffled at this
> > point...
>
>  It's interesting, isn't it? In their recent monograph on the birds
> of western Colorado, Bob Righter et al. state the following for Swainson's
> Thrush: "Even during spring and fall migration, rarely found outside of
> breeding habitat, suggesting that most birds migrate through the mountains
> and mountain valleys." Coen Dexter, one of the coauthors of that monograph,
> put it even more dramatically to me (personal communication in front of 100+
> folks when I was doing Q&A at a public talk; insert frowney-face
> here): There do not appear to be any credible records in western Colorado
> away from mountains and mountain valleys. Conversely, if you go east of the
> Divide, you can see 100+ per day on spring migration in Colorado.
>
> Anecdotally, that was my impression back in my Nevada days. Swainson's
> Thrush is common as dirt in the broadleaf forests of, say, the Ruby
> Mountains (northeastern Nevada). But it was notable enough in the lowlands
> for us to put it on the hotline. And those lowland records tended to be from
> the far west (Reno area) and south (Las Vegas area). I wonder if they were
> mainly Russet-backed (Pacific slope) birds, not Olive-backed (everywhere
> else) birds.
>
> Best, --Ted Floyd
>
> Lafayette, Boulder County, Colorado
>
>
>
>
>
>
>



-- 
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Brian L. Sullivan
Pacific Grove, CA

eBird/AKN Project Leader
www.ebird.org
www.avianknowledge.net

Photographic Editor,
Birds of North America Online
http://bna.birds.cornell.edu/BNA

Cornell Lab of Ornithology
159 Sapsucker Woods Rd.
Ithaca, NY 14850

Photographic Editor,
North American Birds
American Birding Association
www.americanbirding.org

bl...@cornell.edu
609-694-3280
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