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ID-FRONTIERS for November 1-4, 2000
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Subject: a dark juvenile YUKON GULL
From: Cameron Eckert <cameron.eckert(AT)GOV.YK.CA>
Date: 1 Nov 2000 11:51am
Hello all,
I've posted some images of a dark juvenile gull which I photographed in
Whitehorse in September 2000. I am keen to receive some feedback on this
bird. I should point out that virtually all of our local juvenile Herring
Gulls have departed and this bird was part of our fall movement of Thayer's
Gulls, Glaucous Gulls, and myriad oddities and hybrids.
http://www.yukonweb.com/community/ybc/gull_yt1.jpg
http://www.yukonweb.com/community/ybc/gull_yt2.jpg
http://www.yukonweb.com/community/ybc/gull_yt3.jpg
http://www.yukonweb.com/community/ybc/gull_yt4.jpg
Check the following map if you are not familiar with the Yukon's position
on the planet:
http://www.yukonweb.com/community/ybc/ytmap.gif
Whitehorse is located at about the tip of the red arrow.
other views of the Yukon:
http://www.yukonsite.com/_derived/yukonmap_links.htm_txt_yukon.gif
http://www.sundogguides.com/images/map.gif
Regards,
Cameron Eckert
Whitehorse, Yukon.
http://www.yukonweb.com/community/ybc/
[ << | >> | ^^ ]
Subject: Re: mystery YUKON GULL
From: Alan Wormington <wormington(AT)JUNO.COM>
Date: 1 Nov 2000 12:29pm
YUKON MYSTERY GULL:
My opinion is that it is a juvenile Thayer's Gull, unusually dark perhaps
because it is recently fledged?
One characteristic that Thayer's seems to have more than other species --
although I don't know if it is completely diagnostic -- is the presence
of distinctive back feathers that each have the pattern of / dark brown /
blackish / creamy-white / in this sequence.
This feature -- plus other standard features in the photos -- points to
Thayer's Gull in my opinion.
Alan Wormington
Leamington, Ontario
Visit my Web Page (not much yet, but we're working on it):
www.Point-Pelee.com
[ << | >> | ^^ ]
Subject: Re: BIRDWG01] a dark juvenile YUKON GULL
From: Phil Pickering <philliplc(AT)HARBORSIDE.COM>
Date: 1 Nov 2000 1:04pm
Cameron and all,
Referring to:
http://www.yukonweb.com/community/ybc/gull_yt1.jpg
http://www.yukonweb.com/community/ybc/gull_yt2.jpg
http://www.yukonweb.com/community/ybc/gull_yt3.jpg
http://www.yukonweb.com/community/ybc/gull_yt4.jpg
My impression is that this is just an unusually dark Thayer's. The
silvery underwing with thin dark trailing edge to the outer primaries,
pronounced striped look to even the outermost primaries and all
the secondaries created by pale inner webs and dark outer webs,
barring at the base of the retrices, dainty proportions and lengthy
primary projection, short, dark pink legs showing little tarsi, apparent
lack of notching to the dark scaupular centers, and darker smudge
around the eye all seem right for Thayer's to me. The size and shape
of the bill, streaked look to the upper breast and neck, tertials closer
in shade to the coverts than primaries, rounded crown, gently sloped
forehead, and forward placement and proportionately large look to
the eye all seem Thayer's-like to me, also.
The relatively solid, dark coverts seems quite unusual for Thayer's,
but perhaps what you would expect concidering the dark coloration
to the rest of the bird. My guess is that this is the extreme dark end
of the possible spectrum for Thayer's. Other that the coloration, I don't
see anything else un-Thayer's-like in structure or patterning that might
indicate a hybrid of some kind.
Nice photos! Thanks.
Phil Pickering
Lincoln City, Oregon
philliplc(AT)harborside.com
[ << | >> | ^^ ]
Subject: Yellow-legged Gull
From: Brian Small <BrianJSmall(AT)AOL.COM>
Date: 2 Nov 2000 6:12am
Dear All
I have put another article on gulls on www.surfbirds.com, this time on
Yellow-legged Gulls. One of the individuals discussed is a bit contentious in
that it looks very like a Lesser Black-backed Gull. I explain my reasons for
identifying it as YLG, but would like comments.
It is also interesting to compare the images with the putative 1w YLG at New
Jersey on Bob Lewis's site, which I think is clearly a LBbG.
Brian Small
[ << | >> | ^^ ]
Subject: Plain-capped Starthroat tail pattern
From: Will and Beth Russell <russell(AT)RTD.COM>
Date: 4 Nov 2000 12:46pm
Plain-capped Starthroat is a rare but regular mid to late summer visitor
to southeastern Arizona. In the three cases where I've come across this
species unexpectedly, my eye went first not to the long bill or the face
pattern or to the white on the flanks or rump but to a tail pattern
apparently unique among North American hummers. In Plain-capped
Starthroat, rectrices R2-R4 have small (circa 5mm x 5mm) areas of white
on the tip of inner webs. In R5 (the outhermost rectrix), the white is
slightly more extensive (circa 7mm) and extends to both webs . The net
effect is to give the spread tail the appearance of a narrow, broken
white terminal band. In other North American hummers, only rectrices
R3-5 are noticeably white tipped and the tipping is more extensive and
extends to both inner and outer webs. The effect in Plain-capped
Starthroat is very different and I believe incorrectly illustrated in
existing field guides.
A review of limited material in the University of Arizona collection as
well as concentrated field experience near Alamos, Sonora, last December
suggest that the described pattern applies to all ages and sexes. Small
individual variation in the amount of white in R2-5 may reflect some
systematic age/sex difference but it's doesn't alter the overall effect.
Will Russell
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