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 > > > > > > > -- =========== 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 ------------------------------- -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html --
