Jon, Mike, Richard et al.,
Yesterday when I saw the first two pictures of the perched gull my "gut
feeling" immediately ruled out Thayer's and I indeed thought of Vega Gull,
barabensis-Steppe Gull, mongolicus-Steppe Gull or Slaty-backed Gull.
Now I've seen Richard Baxter's flight shots. The large pale window in the
primaries indeed immediately rules out the fuscus complex including Heuglin's
Gull (heuglini and taimyrensis), but it is in my opinion also way too large for
so-called "Herring Gull Complex" (Eurasian Herring Gull, American Herring Gull
and Vega Gull) and for the "Yellow-legged Gull group", including mongolicus and
barabensis. The pale window (formed by the pale inner webs of the primaries vs.
dark blackish brown outer webs and tips) in the Cooktown bird actually reaches
P9! In addition .
The pattern of the primaries (which looks good for Slaty-backed, but also for
Thayer's), the spotted/barred upper and under tail coverts with broader white
than dark bars (looks better for Slaty-backed Gull than for Thayer's and also
rules out American Herring Gull), the almost solid dark blackish brown tail
(which speaks against Eurasian Herring Gull and the "Yellow-legged Gull
complex", but also against Vega Gull), the bleached scapulars (which in my
opinion don't necessarily rule out a first-winter Slaty-backed Gull), and the
bill shape with a relatively flat gonydeal angle (which would rule out a male
Slaty-backed Gull) makes me think of a female first winter Slaty-backed Gull.
I am looking forward to more comments that hopefully will finally lead to a
positive ID of this interesting bird!
Nikolas
----------------
Nikolas Haass
Sydney, NSW
----- Original Message ----
From: Jon King <>
To: ;
Sent: Sunday, February 17, 2008 3:17:12 AM
Subject: Vagrant Gull
Hi Aus birders,
Repeated below is the text of a message I sent to Mike Carter yesterday
after he sent me a couple of the initial photos of the Cooktown gull.
I have had the good fortune (!) to study gulls in throughout the North
Pacific rim very extensively over the past decade while resident in the
western US and travelling widely throughout East Asia, much of the time
specificially surveying for gulls.
The relatively small head and bill, and the patterning of the scapulars
quickly eliminates Slaty-backed Gull (their new second year scaps are
largely unmarked and clean darker grey, and they are generally much
heavier in the head and bill). The relatively white head, scapular and
covert patterns, and much darker primaries, secondaries and tail largely
eliminate Thayer's Gull, and immediately strongly indicate this bird is
in the "herring gull complex", the taxonomy of which depends very much
on which book you read and personal opinion.
Among the likely candidates (ie. those "herring" gulls occuring in
western North America or East Asia, vegae, mongolicus, smithsonianus and
"taimyrensis"), the latter two can be eliminated on structure and
plumage traits, which pretty much leaves the two common "herring" gulls
of East Asia, vegae, Vega Gull, and mongolicus, Mongolian Gull.
In my note to Mike my initial look indicated that this bird fitted Vega
Gull well, but in my early morning haze I hadn't given adequate thought
to mongolicus. The Cooktown bird is a little browner in the remiges and
tail than is typical for either of those taxa, but that is to be
expected for a temperate bird that has been worn and faded in tropical
sun recently. Pending some more photos, especially flight shots, it
should be possible to distinguish between those two options, as the tail
patterns especially are rather different. What is currently visible of
the tail in perched shots suggests vegae, but some aspects of the
pattern of the new scapular and mantle feathers may lean towards
mongolicus.
I look forward to the ID discussion in due course, and hope to provide
some comparative photos and more commentary when time permits.
Best wishes, Jon.
Jon King
California, USA and West Sussex, UK.
+++++++++++++++++++++++++++++++
Hi Mike,
A quick initial look suggests that this bird shows many of the
characters of the herring gull taxon vegae, referred to under most
modern gull taxonomies as Vega Gull. That was my suspicion when you
suggested the possibility of thayeri, as some worn female vegae can have
a surprisingly similar look to that species. The pattern of the coverts
is typical of vegae, and especially helpful is the pattern of the new
scapulars, which looks classic for that taxon. The exposed primaries and
tail look rather browner than usual, but then it has also seen a lot
more potent sun than usual in its recent travels than a typical vegae
wintering in Japan or Korea!
Some flight and open wing/tail shots would be very helpful, and probably
decisive.
Without checking all my photos from East Asia - I am travelling on
business until Sunday - I would prefer not to be definitive but that is
my very strong suspicion. Great record (although not entirely
unexpected).
Will be in touch again with more detail shortly, including comparative
shots of similar birds from Japan and Korea.
Cheers, Jon.
>>> richard baxter <> 02/15/08 8:40 PM >>>
Hello all,
I'm on my way back from twitching the vagrant gull which is
currently in Cooktown FNQ. For those intending to head up that way, the
bird is fairly easy to find and was, this morning approachable to within
2m. One of the locals was feeding it his left over bait and chicken..
The bird readily ate everything thrown near it.
To find it, drive into the main street of Cooktown and down to the boat
ramp/jetty area. It has been seen daily in this 300m stretch for 3 days
now. The road from Cairns is all tarred and fine but be very careful of
wandering cattle at night.
I've taken over 100+ pics, so now its time to hit the books and try to
ID it. So far its been narrowed down to Thayer's, Herring,
Slatey-backed, Vega, the list goes on!!
Cheers
Richard Baxter
===============================
www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
===============================
===============================
www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
===============================
____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page.
http://www.yahoo.com/r/hs
===============================
www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
===============================
|
