Comments on the possible Slaty-backed Gull at Conowinga Dam,
Phil Davis (pdavis@ix.netcom.com)
Sat, 06 Mar 1999 15:44:37 -0500
FYI (from BIRDWG01):
Phil
>Date: Sat, 6 Mar 1999 16:39:43 -0500
>Reply-To: Angus Wilson <wilsoa02@ENDEAVOR.MED.NYU.EDU>
>Sender: NBHC ID-FRONTIERS Frontiers of Field Identification
> <BIRDWG01@LISTSERV.ARIZONA.EDU>
>From: Angus Wilson <wilsoa02@ENDEAVOR.MED.NYU.EDU>
>Subject: [BIRDWG01] Comments on the possible Slaty-backed Gull at
> Conowinga Dam,
> Maryland
>Comments: To: Miliff@AOL.COM
>To: BIRDWG01@LISTSERV.ARIZONA.EDU
>
>******* Comments on the possible Slaty-backed Gull at Conowinga Dam,
>Maryland ********
>
>Marshall and Frontier's subscribers:
>
>Having not had time to get down to Maryland, I was very interested to
>finally see photographs of the possible Slaty-backed Gull at Conowinga. My
>immediate impressions scrolling through the photos were mixed and at the
>moment, I am not convinced this can be safely identified as a Slaty-backed
>Gull.
>
>Reading your highly informative e-mail, I see that other have expressed
>similar concerns. Andy Guthrie, who has also seen numerous adults in the
>Aleutians, Commander Islands and on the Kamchatka Peninsula, expresses the
>same concerns. While individual variation needs to considered, the
>combination of so many weak points on one bird makes the identification
>difficult. To be honest, neither Andy or I have any idea what this bird is!
>
>Here are the key points:
>
>1) The width of white trailing edge is way too narrow. The difference is
>very obvious when comapred to the many pictures of adults (basic or
>alternate) now available on the web.
>
>For example look at:
>
>http://www.west.net/~dj/schi4.htm
>http://www.best.com/~petrel/Angus.SBGU.1.jpeg.html
>http://www.best.com/~petrel/Angus.SBGU.6.jpeg.html
>http://www.best.com/~petrel/AsianGulls.html
>http://www.fordham.edu/lewis/birds/adSlatys/sbguadf1.JPG
>
>****
>By the way, several of Allen Chartier's pictutes on Bob Lewis's
>'Slaty-backed Gull page' appear to be Vega Gulls. For example look at
>http://www.fordham.edu/lewis/birds/adSlatys/sbguadf4.JPG
>http://www.fordham.edu/lewis/birds/adSlatys/sbguadf5.JPG
>****
>
>2) The mantle tone is rather light. This is difficult to judge from the
>pictures (and unsafe given the effects of film, scanning and browser
>presentation). If the bird was really lighter than graellsii (as stated in
>your e-mail) then it is too light! Ignoring the 'pale' Slaty-backs reported
>from various places in North America, my experience in Japan and Russia is
>that the vast majority of adults are very dark. Again you quote a statement
>to this effect from the late Peter Grant.
>
>3) Legs not especially pink. All the full adults I have looked at, even
>those in basic plumage with extensive head streaking (Dec/Jan, Japan) have
>bright (bubble gum) pink legs. This impression seems to hold true if you
>surf the web pictures taken in the Far-east.
>
>4) The primaries and secondaries appear too pale on the underwing views.
>Admittedly this is hard to judge in these rather dark MD shots.
>
>In addition, the wings at rest look rather too long - the primaries
>project too far beyond the tail. Also to my eyes the characterisitc
>string-of-pearls seems weak. Could this just be a product of difficult
>photgraphic conditions?
>
>Just as we wrote this note, Nick Lethaby's message to ID-Frontiers came in.
>As most of you will know, Nick has very extensive experience with this
>species (Japan, South Korea etc) and it is gratifing to see that he makes
>many of the same points.
>
>Hope this helps, and great job on finally getting these pictures on the web
>for all to see and enjoy.
>
>Angus Wilson (wilsoa02@popmail.med.nyu.edu) and Andy Guthrie
>(Andrew.Guthrie@ey.com)
>
>***********************************
>Angus Wilson
>New York City
>tel: (212) 263-0206
>Fax: (212) 263-8276
>E-mail: wilsoa02@popmail.med.nyu.edu
>Bird ID Web Site: http://www.best.com/~petrel/index.html
================================================
Phil Davis
home: PDavis@ix.netcom.com Davidsonville, Maryland USA
work: PDavis@OAO.com Greenbelt, Maryland USA
================================================