Unusual first-basic Ring-billed Gull
Breezy Point, New York City, 17 Jan 1998
all photos courtesy of Andy Guthrie, copyright 1998
The photographs were taken late in the afternoon in very overcast (thus
dark) conditions.
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Photo 1. Question bird is on the right with wing raised showing solid dark tail band and extensive white upper tail coverts.
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Photo 2. In flight showing the tail and upper-wing patterns.
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Photos 3 and 4. Landed bird showing details of head, bill, flanks,undertail and mantle. |
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Photo 5. Right-hand bird landing next to a trio of smithsonianus Herring Gulls, again showing dramatic tail pattern.
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COMMENTS BY ANGUS WILSON:
Tail pattern: A very striking pattern! Solid black (or very dark brown)
band accounting for ~1/3 length of tail (see, photo#1, photo#2 and photo#5).
Very narrow white terminal band barely visible in field but apparent in
some of the photographs (see photo#1). We noted in the field that the outer
web of the outertail feather appeared white and unmarked. Uppertail coverts
were white except for a few faint small spots of pigment (see photo#1) this
white patch extended as a wedge between the scapulars to the base of the
mantle. The undertail was generally unmarked except for four evenly spaced
thin black bars (see photo#1 and #3).
Mantle: light gray with some dark flecking (see photo#3), lacking a obvious
'saddle' effect. In field didn't appear as dark as in photo#4.
Flank Pattern: Weak collar of diffuse smudges (see photo#3). Uneven markings
extending from nape down the flanks (forming weak crescents)
Bill: Sharply divided black tip and pink (slightly orange?) base. Seemed
too deep (especially at gonys) and angular for Common Gull.
Head shape: Not particularly 'rounded' as would be expected for Common Gull.
Size: Close to Ring-billed Gull in size sometimes appearing a tiny bit
smaller (less bulky), presumably reflecting the expected size difference
between individual Ring-billed Gulls.
Behavior: Generally picking around on higher portions of beach. Notably
aggressive towards other gulls. Significance??
Analysis: We believe this is a first basic (first winter) Ring-billed Gull
(Larus delawarensis) and not a Common Gull (Larus c. canus) as the tail
pattern might first suggest. We favor Ring-billed Gull based mainly on the
light rather than darker gray mantle, pale greater wing coverts, the heavy
bill shape and overall size/jizz of the bird. AW has extensive experience
of first winter Common Gulls from Britain. Mew and Kamchatka Gulls (L. c.
brachyrhynchus and L. c. kamtschatschensis, respectively) can be eliminated
Interestingly, a very similar bird was recently observed at the Conowingo
Dam, Maryland, USA at the beginning of this year (Mark L. Hoffman and
others). These two observations lend further support to the notion that
tail pattern alone is insufficient to separate first basic Common and
Ring-billed Gulls. Subtle reference to this fact is made in several key
identification texts but we have not actually seen published pictures to
reinforce this fact.
send comments to
Angus Wilson