ID-FRONTIERS for April 16-22, 2000

Messages are displayed in the order they were received.  Subject  From  Date   Time   Re: yes, it's a gull again....   Adriaens, Peter   Mon, 17 Apr 2000   2:53am   Re: yes, it's a gull again....   norman van swelm    Mon, 17 Apr 2000   8:56am   Re: yes, it's a gull again....   Bruce Mactavish    Tue, 18 Apr 2000   6:27pm   Re: yes, it's a gull again....   Dick Newell    Tue, 18 Apr 2000   11:53pm   Cans and Pochard   paullarkin    Sat, 22 Apr 2000   9:49am   Brant photos   P. A. Buckley   Sat, 22 Apr 2000   10:28am

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Subject: Re: yes, it's a gull again....
From: "Adriaens, Peter" <padriaens(AT)C2000.BE>
Date: 17 Apr 2000 2:53am

Hi all,

I think this bird's large size (compared to the American Herring Gulls in
pic1), structure (obvious tertial step, long legs, fairly thick and heavy
bill, rather short primary projection -- suggested in pic2 --), contrasting
black-and white wingcoverts, and rather thin tail band in flight are at
least good indications that it is a (first summer) Great Black-backed Gull.

Though very worn, the inner greater coverts clearly show only three dark
bars, on a whitish background. Yellow-legged and Lesser Black-backed
typically show four or even five dark bars, on a more buffish background.
The anchor pattern on scapulars and mantle is clearly too bold for
Yellow-legged; some lower scapulars even show almost diamond-shaped dark
centres. The pattern is too contrasting (almost blackish centres on a
whitish background) for Lesser Black-backed.

Bill size is certainly still within the variation of Great BB (perhaps it's
a female ?); in pic1 the bill looks decidedly thicker than in the American
Herring Gulls nearby, which should rule out Lesser BB, and even a normal
Yellow-legged.
The tailband is quite solid for Great BB, but when the tail is spread, it is
still (much) thinner than in Lesser BB or YLG, so not out-of-range for GBB.
Cramp & Simmons state that the tailband is 15-25 mm wide on t6, and 15-45 mm
wide on the central tailfeathers. 45 mm, that's nearly two inches... In
addition, the irregular stripes or bars on the bases of these feathers are
sometimes fairly solid and may coalesce with the subterminal band. According
to Cramp, the tail pattern is sometimes identical to Yellow-legged Gull, and
I certainly would agree.

As for moult, first immature pre-breeding GBB may moult partially until
April, while the complete first immature post-breeding moult starts much
earlier than in adults, i.e. in April. Therefore, as often is the case in
large gulls, there may be an almost continuous moult in these birds, so I
think it is not that odd to see some new wing-coverts in a first summer GBB.
Besides, if this were a YLG having replaced a number of wingcoverts, one
would expect it to have replaced some mantle/scapular feathers as well,
which would certainly not show such bold markings.

I do not want to go into statistics or percentages here, but I would say
that by April, many (first summer) Great Black-backed Gulls may look like
this.

Best regards,

Peter Adriaens
Belgium

==>-----Original Message-----
==>From: Martin Reid [mailto:upupa(AT)AIRMAIL.NET]
==>Sent: zaterdag 15 april 2000 3:36
==>To: BIRDWG01(AT)LISTSERV.ARIZONA.EDU
==>Subject: [BIRDWG01] yes, it's a gull again....
==>
==>
==>Dear All,
==>Please go to the following web page to view the latest
==>manifestion from the
==>Texas Odd Gull Factory:
==>http://www.martinreid.com/gullsp11.html
==> - if you feel that this is a GBBG, can you please tell me
==>what percentage
==>of GBBGs look like this? Then, what are the odds of getting
==>two of these
==>buggers in Texas in four years (where we are lucky to get
==>one or two GBBG
==>per year)???
==>Thanks!
==>Martin
==>Martin Reid
==>upupa(AT)airmail.net
==>http://www.martinreid.com  or  http://www.cyberramp.net/~upupa
==>


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Subject: Re: yes, it's a gull again....
From: norman van swelm <Norman.vanswelm(AT)WXS.NL>
Date: 17 Apr 2000 8:56am

Martin Reid wrote:
> - if you feel that this is a GBBG, can you please tell me what percentage
>of GBBGs look like this?

Even tough the bird is big and of similar size as GBBG it would not be
considered a GBBG in Europe. European GBBG's in 1st winter plumage are much
paler with an extensive pale wingpanel formed by the pale webs of the inner
primaries.
Norman van Swelm


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Subject: Re: yes, it's a gull again....
From: Bruce Mactavish <bruce.mactavish1(AT)NF.SYMPATICO.CA>
Date: 18 Apr 2000 6:27pm

This week's Texas Odd Gull installment comes with above average quality
photos, but is still not straightforward.  It is not a Lesser Black-backed
Gull because it is obviously too large when compared to the Herring Gulls
and the pale markings in the scapulars and lesser & median coverts are too
extensive.  Is it a Great Black-backed Gull?

The bill looks long, especially between the gonydeal angle and the tip.  The
culmen drops gradually over a considerable distance to the tip.  The
stubbiness of the thick billed GBBG is created by a short upturn between the
gonydeal angle and the tip combining with a steeply dropping culmen.  The
Texas bird shows a long sloping forehead enhancing length of the bill.  The
bill looks as if it was pulled out from the head. The area between the eyes
and bill on a GBBG looks thick enough to support the power of a massive
bill.  The blocky headed, thick billed and overall powerful appearance
typical of GBBG is lacking on the Texas bird. The neck also seems
proportionately thin for a GBBG.

The lesser and median wing coverts are roughly equally divided between light
and dark markings.  The greater coverts are well over 50% dark.  First
winter GBBGs can be this dark.  On a typical GBBG the inner (lesser, median
and greater) wing coverts are over 50% white with bold, widely spaced dark
barring.  Perhaps 1 in 150-200 is so dark that even the innermost greater
coverts are mostly dark with only faint broken barring.

The tail band pattern fits into the wide variation of GBBG tail bands.  The
incomplete view of the undertail coverts shows unusually heavily barring for
a GBBG.

I am not convinced that the pale fringes, or lack of, on the wing coverts
means that there are two generations of feathers.  It may be a variation in
feather pattern.  Sharper photos would make it easier to detect any feather
wear.

In summary I think the bird is not a Lesser Black-backed Gull and probably
not a Great Black-backed Gull.  Yellow-legged Gull should be investigated.
What does a 1st winter Kelp Gull look like?

Bruce Mactavish
St. John's, Newfoundland, Canada
bruce.mactavish1(AT)nf.sympatico.ca


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Subject: Re: yes, it's a gull again....
From: Dick Newell <Dick.Newell(AT)SMALLWORLD.CO.UK>
Date: 18 Apr 2000 11:53pm

Re http://www.martinreid.com/gullsp11.html

Although it looks odd, I think this is probably a GBBG (yes, they are very
variable too). In various replies, comments have been made about the
apparent bill and head shape. Whether a bird has a small, thin, thick or
large bill is critically dependent on it's size relative to the head, which,
in turn, is critically dependent on the state/disposition of the head
feathers. This bird's head doesn't look pristine to me - probably because
it's spent too long in the sun, so I suspect it's apparent longness is due
to reduced feathering on the head.
I really don't think it is a LBBG, Kelp or any form of Yellow-legged Gull
and I am not inclined to go for the hybrid argument on this one.
Dick Newell


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Subject: Cans and Pochard
From: paullarkin <paullarkin(AT)PGEN.NET>
Date: 22 Apr 2000 9:49am

This is a multi-part message in MIME format.

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What Ho!
Some of you may remember my posting about the pale "horn" noted on a =
recent Can in the UK. This feature has also been noted by a British =
observer on Cans in Texas this Feb. I checked on birds in a collection =
here last week. Adult drakes show this feature. It is due to the =
vermiculations only beginning on the rear portion of the flank panel, =
the fore panel being white. The one first year bird I could find showed =
a uniform panel. I though this may be of interest to those in the US as =
this feature is never shown by Common Pochard and may be useful as an =
indicative feature on distant flocks of birds.
Cheers
Paul

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Subject: Brant photos
From: "P. A. Buckley" <pabuckley(AT)GSOSUN1.GSO.URI.EDU>
Date: 22 Apr 2000 10:28am

To illustrate an article for NORTH AMERICAN BIRDS on the various
Brant populations, named and unnamed, we seek color slides of the
following:

Atlantic Coast-wintering  _hrota_
Southern Pacific coast-wintering  _nigricans_
Puget Sound-wintering  _nigricans_
western Europe-wintering  _hrota_
nominate  _bernicla_  (='Dark-bellied' Brant or Brent Goose).

Ideally, we would like to have first-winters taken on first arrival
on wintering grounds, and then in very late winter/dearly spring,
plus adults at the same times of year.

Birds standing on dry land and showing underparts to the undertail
coverts would be best, but shots showing how each type appears on the
water will also be terrific.

If anyone has any flight shots of any and all age-classes of the
above 5 populations showing them from the side with upraised wings,
they would also be much appreciated.

Most desirable of all are slides with birds from more than one of the
above groups in the same frame.

And don't forget that a really good vertical picture is a potential cover.

Feel free to contact me at any of the addresses below, but email is
fastest and most reliable.

Many thanks to all.
P.A. Buckley
Box 8 @ Graduate School of Oceanography
University of Rhode Island
Narragansett RI 02882

<pabuckley(AT)gsosun1.gso.uri.edu>

01-401-874-4201 (off)
01-401-874-6887 (fax)

'In the fields of observation, chance favors only the mind that is prepared'
   --- Louis Pasteur