[Fwd: Gulls and such Mon. 2/15/99 (VA)]

Edward Jendrek (aj97@bellatlantic.net)
Thu, 18 Feb 1999 12:56:48 +0000 

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Date: Tue, 16 Feb 1999 23:10:41 -0400
To: Valley Birds <jwcoffey@tricon.net>
From: Valley Birds <jwcoffey@tricon.net>
Subject: Gulls and such Mon. 2/15/99 (VA)

Date: Tue, 16 Feb 1999 15:35:31 -0500
From: David Abbott
Subject: Gulls and such Mon. 2/15/99 (VA)

Bird Report=20
Mon. Feb. 15, 1999 from the Eastern Shore of Virginia

Obs. David Abbott, June Harper and Rigdon Currie (visiting from Pt. Reyes
Bird Observatory).

Weather:  Feb. 14: icy cold with bone numbing wind all day.  Sunny.  Winds
died over night.  Feb 15: calm, cold predawn, warming into the 50's by mid
morn.  Sunny.

The Eastern Shore of Virginia, principally Northampton Co. and the
Chesapeake Bay Bridge-tunnel (CBBT), offers opportunity for real
contributions as our knowledge of avifauna of the mid Atlantic states is
embryonic and under continual change.  Over the above period, we made a
quick trip down the VA coast to the CBBT and had some great successes.

The real story was the gulls in Northampton Co.  We checked the Oyster dump
in Cheriton on Sunday around 1600.  Here we found 3,500 gulls, 2790 Herring
Gulls (Larus smithsonianus, followed by Great Black-backed (L. marinus) and
finally Ring-billed Gulls (L. delawarensis).  We didn't have time to view
as much as we'd like as it was getting late.

ELEVEN SPECIES OF GULLS

On Monday, we studied the gulls on island 3 and 4 of the CBBT 0800 =AD 1300.=
=20
We found 10,000 gulls feeding in the mouth of the Chesapeake from island 4,
most within 100 yd. of the island.  They were moving E to the shore,
probably sheltered in the mouth of the bay from the extremely high winds on
Sunday.  By 1000 nearly every single gull had gone.  During the two hours
we found and identified 12 species of gulls.  I photographed one 2nd winter
SLATY-BACKED (L. schistisagus) and two first winter THAYER'S GULLS (L.
thayeri).   Moreover, we had very good studies, sharing these birds with
others of: Black-headed Gull (L. ridibundus), one adult winter COMMON GULL
(L. canus), BLACK-TAILED GULL (Larus crassirostris) and one first winter
CALIFORNIA GULL (L. californicus).

I found at 0830 what I'd call a second winter SLATY-BACKED GULL loafing on
the jetty of the 4th island (northernmost) with smithsonianus and marinus.=
=20
Great views hopefully OK photos both at rest and in flight.  We scoped it
from 50 yds in excellent light for 30 min. when it suddenly flew off
heading southeast. Almost as soon as we began scanning, I spotted a first
winter Thayer's Gull landing on the rocks, giving us complete dorsal view
as it did, and we enjoyed the study.   Next, one of the closest gulls to
us, was the Slaty-backed. The Slaty-backed spent most of it's time sitting
on top of a rock among Herrings.  The bird was very cooperative and preened
and shook its feathers and changed positions several times as if to show us
as much as possible.=20

It stood out like a sore thumb.  My initial reaction was that the bird was
either a Slaty-backed or a hybrid. It was noticeably larger than the
Herring Gulls, but I am not sure if this impression was real or partially
because of its unique structure. I was struck by a pale immature Herring
Gull with a strong hammering head (too large for its body) and moderately
thick straight bill with no gony expansion.   My eyes went to the face, and
the large pale gray eyes set in a dark smudge under each eye and extending
behind the eye, where it flared upward slightly, contrasting with the paler
face and head. This gave the bird the appearance of a burning stare. My
initial impression that it was schistisagus solidified after we confirmed
its features.

Structure: four primaries past the tertails, brown and a shade or two
darker than the rest of the bird, each with a narrow pale fringing on the
primary tips.  Each with a large space between tip.  Tip of P9 lining up
with tail tip.  Legs bubblegum pink, short in proportion and bulk of bird.
The bill-shape was utterly unique, rather thick looking with the culmen
arching steeply well past midpoint to the tip; there was no noticeable
gonydeal angle. Bare parts: The bill was dull black, with a fleshy-pink
area in the center of the bill, leaving the tip black. This pinkish area
formed two crescents on each mandible and the black extended inward along
the cutting edge of both mandibles almost all the way to the gape.=20

The tertials were sold brown with some pale internal flecking.  Greater
coverts mainly plain and very pal, lacking barring. Remainder of wing
coverts very plain and pale, lacking pattern.  The tail was solid brown
(all dark), as primaries.  Noticeable narrow white band at the tip and a
soft ragged white area at the base. No retrices contrasty white or barred.=
=20
The tail also had a unique image: dark but soft not black, with gradation
to whitish at base, white terminal band and the feathers seemed brushed
softly with pale around their fringes (with many internal very fine
variegations).=20
In flight the tail appeared all brown, not blackish, and the same tone as
the primaries.=20

Absolutely striking upperwing pattern, of pale inner wing panel that
extended outward through the outer P's with a glossy look to the inner
primaries.  The secondaries formed a brown bar, strongly contrasting with
the panel, but not dark.  This bar was a series of vertical brown stripes
on a paler background.  Most obvious were the gray 'tear drops' which stood
out at the tips of the paler inner primaries.  This gave the bird the look
of paler forewing.   The gray trailing edge caused by dark primary tips
finally blended into the extreme outer P's. The secondaries were slightly
darker than the rest of the wing, although at some angles they looked
slightly paler.=20

Discussion
Plainly, the bird is entirely consistent with Slaty-backed Gull. I have
photographed it but a large series of close-up photos may be needed to
resolve the identification.

 The primary projection is very short, distinctly shorter than
smithsonianus, and one of the shortest I've seen on a large gull, perhaps
similar to glaucescens.  The primaries were very broad and rounded (as 2nd
winter).  On the folded wing, P10 even had a noticeable space between P9.
In smithsonianus, the tail tip should fall about even with P7.

 Generally, it looked at first blush in structure and shape very much like
a dark Glaucous-winged Gull to me.  As indicated, the size - as large as
the surrounding Herring Gulls; the heavy, diffuse streaking covering head,
nape & neck; the bill structure, strong-headed, high crowned profile;
piercing stare and facial expression, the unique tail, primary and
uppertail covert pattern; - all are strong indicators, the features in
combination pointing to Slaty-backed Gull.

If it is not a Slaty-backed Gull, the only possibility is hybrid but it
shows nothing puzzling or characters suggesting it might be something else.
In believe the wing pattern, especially the primary tip marks in
combinations with tail, uppertail coverts, structure and bill to be
diagnostic of Slaty-backed.  Further, the plumage, etc. is not compatible
with Vega Gull (L. a. vegae). However, unlike a typical hybrid, its bill
lacked a prominent gonydeal angle and it had a somewhat paler head and
breast than most such hybrids.  From what I have seen thus far, I am
uncomfortable passing it off as any kind of hybrid and am leaning toward
the theory that it actually is a Slaty-backed.  I consider, perceived
difficulty accepted first winter plumages of thayeri, schistisagus, etc. to
actually be more identifiable than adults.=20

Others:  A fascinating array of gulls and their plumages.  The
smithsonianus, presumably from different geographic areas, were displaying
their variability to the hilt.  Several first winter smithsonianus (by
everything else) showed nice well marked tailbands.  I studied others that
probably could be keyed out as first-winter Herring Gull
___________________________________________the tail, rump, and covert and
tertail pattern of one of the European races.  Many smithsonianus had juv.
scaps. and few were worn.  I took quite a few photos.

Isl. #4 (Slaty-backed fw, Thayer's-3, fw, California-fw, Lesser
Black-backed Gulls-4, 3 fw, 1 2nd w)=20
Isl. #3 (Black-tailed-ad, Common-ad, Black-headed Gulls-ad)

Wise Point:  one adult BLACK BRANT with American; PRAIRIE WARBLER; King
Rail.

Oyster:  190 Marbled Godwits, 45 Willet, 200 Black-bellied Plover, 76
Western Sandpipers, Long-billed Dowitcher, one lt. morph Rough-legged Hawk,
three Saltmarsh Sparrows.  Also, one GREEN HERON, 3 Tricolored and one
Little Blue Heron and 3,000 brant.

Good luck!
David Abbott
Ashburn VA





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