Indeed a splendid talk by Martin and a thought provoker -- brought back some memories of my older days including the initial excitement over the Laughton buteo and the one below written up in British Birds Vol 75: 2:88 -- no-one really thought about eastern Common Gull back then
Second-winter Common Gull with prominent tail band On 14th March 1981, at Cleethorpes, South Humberside, I noticed a gull which
resembled a typical second-winter Common Gull Larus canus except for
prominent traces of a black tail band (fig. 1). Never having seen a Common
Gull of this age with any sign of a tail band, but having seen several
photographs of second-winter Ring-billed Gulls L. delawarensis showing this
feature, I studied it closely. I consulted the literature for the source of my
mistaken belief that second-winter Common Gulls never show a tail band. I
found that P. J . Grant (Brit. Birds 66: 115-118, repeated in Frontiers of Bird
Identification, 1980) stated of second-winter Ring-billed Gulls 'over half. . .
retained prominent traces of a dark bar on the secondaries and a subterminal
tail band. These marks are diagnostic, for Common Gulls hardly ever
retain traces of immaturity on the inner wings and tail in sufficient strength
to be visible in the field', and W. R. Hirst (1979, Birds of Cornwall) stated,
when describing the broken tail band of a second-winter Ring-billed Gull,
'this feature is apparently never shown by similar aged Common Gulls and
is diagnostic of Ring-billed Gulls of this age'. In a later paper, however, P.J.
Grant (Brit. Birds 72: 142-182) noted for second-year Common Gull
'individuals showing prominent traces of a secondary bar or tail band are
rare'. Obviously, this feature is not diagnostic of second-winter Ring-billed
Gull and should be used with caution when this species is suspected.
GRAHAM P. CATLEY
13 West Acridge, Barrow-on-Humber, South Humberside
88
Notes 89
PJG estimates that probably less than one in 300 second-year Common Gulls show obvious
subterminal black tail markings, whereas they are shown by probably the majority of secondyear
Ring-billed Gulls. An exceptionally 'retarded' tail-banded second-winter Common Gull
which he observed in Scilly in October 1977 also showed several brown coverts on the inner
wing, forming a partial carpal-bar, and lacked the usual mirrors on the outer two primaries.
and here's one from Barton October 17th 2010
http://pewit.blogspot.com/2010/10/first ... -gull.html