Greetings all,
Over recent weeks there has been a lot of discussion and speculation about the
origin of the pale Song Sparrow wintering along Rentenaar Road on Sauvie
Island. I have gone to see this bird twice and like many others I have taken a
number of photographs of it. Many who have seen this bird have come to refer to
it as an "Eastern" Song Sparrow, with some going so far as assigning it to
"Song Sparrow melodia/atlantica" in their eBird reports. The Columbia County
eBird reviewer, who is not an OBOL subscriber, has left these reports in the
county review queue, unsure about how to process them. He is being rightfully
cautious about wading into this mire in my opinion.
I think it is safe to suggest that when most birders use the term "Eastern" to
describe birds of a subspecies or subspecies group, there is an inherent
implication that the source population of the birds is east of the Rocky
Mountains, or from the states and provinces that we think of as making up
"Eastern" North America. After reviewing the Birds of North America (BNA)
online account descriptions for Melospiza melodia melodia and M. m. atlantica,
along with photos of Song Sparrows from the eastern U.S. and Canada, I don't
think that we can safely assign the Rentenaar Road bird to this designation in
eBird. In my opinion, calling it an "Eastern" Song Sparrow is misleading, other
than assuming it originates from a population from east of the Cascades. The
Sauvie Island bird shows blackish dorsal streaking on a grayish base color
rather than reddish-brown dorsal streaking on a brown base color as it is
described for M. m. melodia in the BNA account. Song Sparrows photographed in
what should be the heart of the M. m. melodia range are indeed noticeably
browner on the back. M. m. atlantica is apparently grayer above, but it is
described as resident (non-migratory) with a rather restricted range that is
confined to the salt marshes along the Mid-Atlantic Coast. M. m. atlantica
seems an unlikely candidate to wander this far to the west.
If you are among those who have labeled this bird "melodia/atlantica" in your
eBird report, I would strongly encourage you to amend your report and list it
as merely "Song Sparrow" until we can get a better handle on what source
population this bird originates from. That said, I would encourage those who
have seen and might see this bird going forward to continue including photos
and video that document the appearance of this bird.
The Song Sparrow as among the most polytypic of North American birds.
Historically, there were as many as 38 recognized subspecies. These have been
reduced to 24 subspecies following Patten 2001 (full citation below) in the BNA
account and those are sub-divided into four different subspecies group
headings. After reading through the BNA descriptions and ranges for various
subspecies, it seems that this bird could be the wide-ranging M. m. montana,
which is highly migratory and breeds in the Rocky Mountains and Great Basin
from se. Washington and north-central Montana south and east to northern New
Mexico and southwest to eastern California. It is described (in comparison to
M. m. melodia) as larger and grayer overall with a more slender bill, all of
which seems to match up with the Rentenaar Road bird.
I am going to take some of my photos and distribute them around a bit in other
circles in an effort to find out where birds that look like the Sauvie Island
bird are prevalent. Hopefully, we can find some more authoritative answers
about this interesting bird. If you live nearby and have an opportunity to go
see this bird, I would encourage doing so. In addition to the Song Sparrow, the
Rentenaar Road seed patches offer a great classroom to gain familiarity with
nearly all of the regular wintering sparrows found in western Oregon and there
are 2-3 really cooperative Swamp Sparrows right along the road at the margins
of the slough between the two patches.
Dave Irons
Beaverton, OR
Patten, M. A. (2001). The roles of habitat and signalling in speciation:
evidence from a contact zone of two Song Sparrow (Melospiza melodia)
subspecies. Phd Thesis, Univ. of California, Riverside.
