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Posted to
ID-FRONTIERS on 29 December 2005 by Ron Pittaway and Jean Iron. This post summarizes the
circumstances leading to the discussion of the identity of the
"adult" dowitchers photographed on 21 July 2005 near Anchorage,
Alaska.
When these
dowitcher photos from Alaska were sent to us we replied that the
"adults" were Long-billed Dowitchers and gave our reasons based on
several plumage characters. However, five Alaskan birders didn't
agree, saying that they were adult caurinus Short-billed. That is
why we posted the photos to ID-Frontiers to clarify their identity.
Only a few people replied to our recent post on ID-Frontiers, but we
got opinions offline from some well-known dowitcher experts. The
geographical breakdown of those who said Short-billed versus
Long-billed is interesting. Five birders from Alaska plus two from
the Lower 48 and one from Japan said Short-billed. All the rest from
the Lower 48 and Canada said Long-billed. To generalize, Alaskans
said Short-billed while most birders outside Alaska said
Long-billed. Those solidly in the Long-billed camp included Alvaro
Jaramillo of California, Cin-Ty Lee of Texas, Kevin McLaughlin of
Ontario, Steven Mlodinow of Washington State, and Joe Morlan of
California. See their comments below. Another expert was uncertain,
but he favored Long-billed. Perhaps Alaskan birders identified these
dowitchers as Short-billed based on location, habitat and season
because the caurinus subspecies breeds locally and it occurs
commonly around Anchorage.
In addition to
the previous e-mail we forwarded from Cin-Ty Lee, here are the field
marks used to identify these Long-billed Dowitchers from four
leading birders in alphabetical order:
1. Alvaro
Jaramillo wrote, "I see both dowitchers in the photos. The adults
are Long-billed, and then there is this bright and somewhat
adult-looking juvenile in two photos. That bird is a Short-billed
Dowitcher. The adults look like fine Long-bills to me, with the dark
breast side patch that is typical at this time of year, very dark
upperparts with thin bands on scapulars, extensive colour below,
etc."
2. Kevin
McLaughlin wrote, "Two species seem to be involved here. Photo #1
shows seven birds, all of them worn alternate Long-billed Dowitchers
in my view. I have no experience with L.g. caurinus in the field but
the birds look just like LBDs with extensive orange on the
underparts, seeming to be darkening with wear, along with variable
flank barring, dark scapulars with narrow white fringing, some scaps
having a point down notch at the shaft. They also may be molting in
the facial area and appear to have very short primaries, falling
short of the end of the tail. Another feature evident in any shot in
which the legs are fully visible are the long tibia. Photo #3 has an
intruder in the foreground, a juvenile Short-billed Dowitcher, which
looks different from our hendersoni, looking duller below
with narrower fringing on the upperparts and which can only be a
juvenile caurinus. In photo #2 what is presumably the same juvenile
L. g. caurinus looms in the left background. The features showing on the
LBDs in photo #1 are shown in this shot and what is best shown in
this photo is the prominent white lower eyelid, barely noticeable in
the SBD. The mid-July timing of these two species being together may
be an interesting reflection of their migration strategy. The
appearance of a juvenile SBD consorting with a good number of adult
LBDs would appear to make sense. I guess the adult caurinus would
have already made their way farther south from Alaska by mid-July
while the LBDs are still gathering and preparing to move."
3. Steven
Mlodinow wrote, "These birds would automatically be called LBDO in
WA (not that such makes the ID automatically correct!). Another
feature which Karlson likes, and I've found valuable, is the
perfectly straight bill in LBDO. Seen in profile, LBDOs really have
an absolutely straight bill, whereas SBDO show a subtle droop. This
can be seen in a few birds in the photos. I believe I've seen birds
that do not conform to this rule, but I think it largely works."
4. Joe Morlan
wrote, "All the adults look like Long-billed Dowitchers to me. They
show salmon undertail coverts, dark upperparts, mostly dark tails,
barring on the sides of the chest, and short primary projection.
Some show the salmon color on the face contrasting with a pale gray
post ocular spot which is good for Long-billed. Some show very long
bills outside the expected range of Short-billed."
Ron Pittaway and
Jean Iron
Toronto, Ontario |
