Hello Justin,
I agree that these two species are very difficult to separate and it is a
shame Richard wasn't able to have another chance at better photos in the
days following his one off observation. A 100% ID for this bird probably is
a difficult ask but Richard's bird showing a half supercilium behind the eye
combined with a necklace was definitely worth getting excited about. His
bird also had plenty of yellow in the throat so possibly an adult showing
all these features, although it would have been nice to look for presence of
brownish remiges etc in an attempt to rule out 1st summer. A photo record of
hind-claw length would also have been useful. I will also quote from Alstrom
& Mild 2003, " appears to only rarely show a dark spotted necklace", this
would be a rare individual of macronyx, but not impossible I guess. " the
call of macronyx is clearly different from that of the European population
of thunbergi, but is apparently similar to the call of thunbergi from
eastern Siberia," so sound recordings in this case would be unhelpful unless
they were of the western bird, this is unlikely. It's also worth noting that
in regards to macronyx "DNA data suggests that it is not closely related to
thunbergi", it's related to the other eastern species but needs more work
done apparently because it is left in limbo for the moment it would seem, an
orphan taxa.
The main reason for my post is that I would like to encourage everyone not
to be put off by the difficulties and treat every "Grey-headed" Yellow
Wagtail to close examination in relation to the features mentioned above.
And Take lots of photos. When Alstrom & Mild 2003 say "macronyx is not
safely separable from thunbergi" I don't think they mean completely give up
trying.
Cheers Jeff.
-----Original Message-----
From:
On Behalf Of Justin Jansen
Sent: Sunday, 30 May 2010 7:08 PM
To: ;
Subject: RE: New Bird for Australia on Cocos
Dear Richard,
The Yellow-wagtail group is one of the most difficult groups in the World.
And in what I'm reading in you're description of the bird a member of the
Eastern Group macronyx can't be excluded safely. Both macronyx/thunbergi are
very close related but both are diverted in various groups, eg Eastern &
Western Yellow Wagtails by some authorities. To be sure on the ID as a
thunbergi, i'm surely more material then those photographs is needed for
example sound-recordings. But as stated by Alstrom & Mild 2003l; In our
opinion, however, macronyx is not safely separable from thunbergi.
Yours,
Justin Jansen
The Netherlands
To: birding-aus <>
Subject: New Bird for Australia on Cocos
From: Richard Baxter <>
Date: Sat, 29 May 2010 07:01:03 -0700 (PDT)
Hello all,
Whilst on West Island Cocos-keeling Islands last fortnight I
located and photographed an unusual yellow wagtail on the edge of the grass
at
the northern end of the runway.
I was able to obtain a couple of average photos that are only suitable for
ID.
Possessing a dark head, it was immediately obvious that this bird had a
short
white supercilium behind the eye. As it moved between clumps of grass and
eventually turned to face us, it's spotted neckless become visible. Whilst
it
stood in that position I took three quick photos and despite several
attempts
during the following five days, these were the only photos I managed to
obtain.
Although there are several integration zones between yellow wagtail ssp and
many ssp are considered inseparable in some plumage states, the combination
of
dark head, short white supercilium not extending in front of the eye and the
spotted necklace across the breast are diagnostic of adult male thunbergi in
fresh spring plumage and therefore Australia's first WESTERN YELLOW WAGTAIL.
If you would like a look at the photos, let me know. I've emailed them to
Simon Mustoe, hopefully he'll be able to put them on bird-o over the next
few
days.
Cheers
Richard Baxter
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