Re: Black-tailed Gull at Bridge-Tunnel
David Gersten (gerstens@erols.com)
Wed, 30 Dec 1998 11:27:04 -0500
Dendroica@aol.com wrote:
> I can't find this bird in the field guides. I recall I saved a description
> from last winter which inadvertently got deleted from my files in an update
> last fall. Will someone provide the field mark details again? Thanks,
>
> Ralph Wall
> Great Falls, VA.
Hi Ralph,
Here is the message I kept on the Black-tailed Gull from last January. Not
sure it was ever cross posted to MDOsprey from Valley Birds.
_____
David Gersten
gerstens@erols.com
Herndon, VA
Subject:
Black-tailed Gull on Chesapeake Bay Bridge-Tunnel (VA)
Date:
Wed, 14 Jan 1998 22:31:16 -0400
From:
Valley Birds <jwcoffey@tricon.net>
To:
Valley Birds <jwcoffey@tricon.net>
From: John Irvine
Date: Wed, 14 Jan 1998 10:17:59 EST
Subject: Black-tailed Gull on Chesapeake Bay Bridge-Tunnel (VA)
On Friday-Saturday, January 9-10, Leonard Teuber, Joe Doherty and I drove over
to the Eastern Shore with the particular desire to see the adult Black-tailed
Gull (Larus crassirostris) which has been reported on the Chesapeake Bay
Bridge-Tunnel for the second winter in a row. We had looked for it
unsuccessfully several times last winter. Its normal range is Japan and the
Kamchatka Peninsula, south to Hong Kong in the winter.
We went first to Craney Island near Portsmouth but found it rather dried out
and with far less birds than usual. Our plan was to visit the CBBT and go on
to Chincoteague, spend the night, and have a second pass at the CBBT on the
way back in case we did not find the bird Friday. Birding was better on the
CBBT as all four islands were now open to birders. We saw two groups of
Common Eiders that together totaled about 45-50 birds, but did not see any
King Eiders. We also did not see any White-winged Scoters, though both other
scoters were present, and numerous Old-squaw. A flock of seven (including
three male) Harlequin Ducks were at the tip of island #3. On the trip back we
found our only Purple Sandpiper, close to the restaurant on island #1. The
Black-tailed Gull has usually been reported from island #4 but despite careful
searching, we did not find it Friday among the many Ring-billed Gulls sitting
on the rocks there.
We stopped by the Eastern Shore National Wildlife Refuge at sunset and stayed
till dusk. A group of high school students from Williamsburg were there
censusing American Woodcocks as they flew out of the woods to the marsh to
feed. We enjoyed their leader's description: "Watch for a softball with
wings flying overhead." A Great Horned Owl hooted from the woods (was it
hurling softballs?), and before it was too dark to see, 8 Woodcock had been
recorded.
Next morning at Chincoteague the birding was great right from the beginning,
with half a dozen Brown-headed Nuthatches over our heads as we came out of the
Refuge Motel. All told we had 77 species for the trip. Snow Geese filled the
sky with honking noise and the rush of their wings. The expectable waterfowl,
raptors, and herons were all around. On the way south we visited the dump at
Oyster but the few gulls present sported no rarities and were quiescent as
there was no landfill operation under way, so we went over to the town of
Oyster, where again birds were scarce--but looking back at the dump now about
a mile distant, gulls were flying all over the place as a bulldozer had
started work. Oh, well.
We were back on the CBBT by 2 p.m. The day was clear, and the wind lighter
than Friday; it was quite comfortable weasther for January. As we drove on
to Island #4 we observed a caravan of birders returning to their cars. We
drove up to them and they showed us the Black-tailed Gull they had been
studying. It was sitting on the northwest side of the island on the rocks
down by the waterline, a standout in the company of about a hundred Ring-
billed Gulls. At first glance one would think from its size, leg color, and
mantle coloration that it was a Lesser Black-backed Gull--but the bill
instantly jumps out as something quite different. We studied it for fifteen
minutes or more in strong sunlight through binoculars and scope at a distance
of about 40 feet. It stood resting most of the time, sometimes preening a
little, but once it jumped to the adjacent rock, spreading its wings and tail
momentarily in the process, allowing us to see briefly the distinctive black
tail-band that gives the bird its name. When we left to search the other side
of the island, we found some birders who had just arrived from the south, and
were able to take them back and show them the bird before we left.
The only pictures we had of this species (other than photographs of this bird
taken by a colleague from Rockingham County, Richard Schiemann, on December
31st, 1997) are on page 135 (plate 56) of Seabirds: An Identification Guide
by Peter Harrison. We noted these differences between the individual we were
observing and the pictures in the book:
Contrary to the standing adult bird diagrammed as #210a, which shows no white
spots on the outer primary feathers, this bird had three such spots. My
recollection is that they were half-moon in shape. These were quite visible
on the black outer primaries of each folded wing, and were very like the three
white spots on the black primary tips of the adjacent Ring-billed Gulls. To
be fair to Harrison, his text does mention spots: "outer 2 or 3 [primaries]
faintly tipped with white" (p. 334). However, I would have judged these
primaries as more than "faintly" tipped. As close as we were, they appeared
prominently tipped.
Also contrary to the standing adult bird #210a in the plate, this individual
had a slightly different color pattern on the bill. Only the very tip of the
lower mandible was whitish; white was virtually absent on the tip of the upper
mandible. Next was a pinkish-red area on both mandibles, in effect a ring.
Behind that was a black area forming another ring, though it was somewhat
scalloped inward on both mandibles. Then, on the lower mandible only,
appeared the real difference from the plate: another red spot on the inner
side of the black ring. The overall effect was to make the patterning on the
bill tilted: outward on the upper mandible, inward on the lower mandible.
Even the black ring seemed tilted overall. The rest of the bill was yellow,
the same color as that of the Ring-billed Gulls nearby. The bill's shape is a
little unusual, also. The downward curve at the front of the upper mandible
appears quite hooked. The precise point at which it starts to curve downward
is at the border between the outer red ring and the black ring. The iris is
pale, like a Herring Gull's. The plate in Harrison shows the legs as a deep
yellow; this individual had greenish-yellow legs and feet, just like the Ring-
billed Gulls with which it associated. Again, Harrison's text seems to be
more precise than the illustration, the text giving the right color.
When the bird jumped to the adjacent rock and spread its tail to my view, the
black tail band seemed very regular. The flying adult bird illustrated in
Harrison (also as #210a) shows the tail band as irregularly shaped on the
second rectrix in from the side of the tail. On our individual, the outer
tail feather is pure white and the next rectrix, as far as I could tell, has a
full black band completely across it. The effect was that of a continuous
white border of approximately the same width all around the black tail band.
It was unlike anything I had ever seen on an adult gull. Almost all the time,
while the bird was still, through the scope I could see that the tail had a
black band on it, even though the tail was folded and the wings were folded
over the rump and tail--and this was while we were looking down upon the bird.
We did not want to disturb it, so we made no effort to encourage it to fly.
Even if you do not see this bird in flight, it is identifiable, if you are
close enough, or your optics are good enough.
I received an e-mail from Kerry Kirkpatrick of Falls Church, who spent Sunday
the 11th looking for the bird without success. Where is this bird when it is
not resting on Island 4 with the Ring-bills? Either foraging nearby, or
perhaps sitting somewhere else on the Bridge-Tunnel, maybe on a light post or
on a piling of the second bridge being built to the west--and at the speed one
must drive, not likely identifiable unless it should be flying. If you miss
it, keep trying. It's a remarkable, beautiful bird when you finally see it.
The real mystery, of course, is the path this pelagic wanderer took to get to
the mouth of the Chesapeake Bay from the other side of the world. It seemed
perfectly healthy, as if it had not needed the assistance of any ship. We had
much to ponder as we drove home after two very satisfying days of birding.
John Irvine
Harrisonburg, VA