We've had this discussion on OBOL before. Separating Hermit from Swainson's
Thrushes in winter.
Lars posting of a diagram of a wing leads into the need to have a bird in
hand - or a lucky diagnostic photo - to confirm that a putative wintering
Swainson's Thrush is not a Hermit Thrush. I'd guess that 99% of birders are
not banders and rarely have a bird in hand. I last banded birds on a
research project in the summer of 1980. Today a limited fraction of
birders carry a powerful digital camera, but do they have it in hand when
the thrush comes by?
Years ago, with three other experienced birders, I saw a Swainson's-type
thrush on the Florence CBC. We saw it at 20 feet away perched up in a bush.
We saw the tail the same color as the back, the pale face, the diffuse
spotting on the breast. On a nearby lawn we saw an obvious Hermit Thrush
with a rusty tail and heavy spotting on the breast. We reported in at the
countdown to Alan Contreras, who was skeptical. I wrote up notes. Not good
enough he said. I got the others to write notes. Not good enough again.
The regional editor finally told me that he couldn't pass the report up the
chain, it wouldn't fly.
I felt like the high school basketball coach whose team led all through the
championship game, only to lose because of a questionable officiating call
in the last seconds. My friends said, "You won that game. You were robbed.
You can be proud of your team." But like the coach I had to swallow and
come back next year. Life goes on.
I know from personal communication that Swainson's Thrushes have been
reported on the CBC for Portland, Salem, Newport, Florence, Tillamook, and
probably others. All were dismissed as mis-identified Hermit Thrushes.
The going wisdom is that ALL Swainson's Thrushes are gone from Oregon by
some date in November and they are well south of Oregon at Christmas.
The argument, from those who know, is: "They're not here. I've never seen
one, and I don't believe people who report them, because they're not here."
That's circular reasoning.
However, we know that birds that are supposed to be well south of Oregon do
show up on the winter, e.g. a Vermillion Flycatcher in Seattle or a
Black-throated Blue Warbler at Bonneville dam, among many others. When that
happens, birders flock to see the vagrant. However, a report of an
out-of-place Swainson's Thrush in December doesn't get chased. Birders
already have it on their year list for Oregon. Reports of wintering
Swainson's Thrushes are not investigated. Still one can ask, "If these
other species can appear out-of-season, why can't Swainson's Thrushes?
Finally, an observer with the heft to be believed saw a Swainson's Thrush in
winter. Shawneen Finnegan found one a few years ago, reported it with
enough detail, and was believed. So now we know it can happen.
Cheers,
Paul Sullivan
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