Dear All



I put together the post below yesterday and for various reasons couldn't post it until now.  With apologies.  We have subsequent to this post seen the details here http://www.cs.mun.ca/~dave/ylgu.html and hope that we or others can look in the roost soonest.



----------------------------------------

Frank Hawkins and I did the early gull shift in DC today.  The Tidal
Basin was gull-free at dawn but there were about 800 gulls roosting on
the Washington Channel, about 50:50 Ring-billeds vs large gulls.  We got
there as it was getting light and initial scans of the flocks showed up
nothing really obvious but Frank picked out an adult Herring Gull type
floating on the water which proved really interesting.  Unfortunately it
departed at 7.10am and we couldn't refind it and we simply didn't get
enough good views of it to clinch an id but it's definitely worth looking
out for.

The bird basically looked like an adult winter Yellow-legged Gull but
with wings that were slightly too short.  It had a completely clean
white head and upperparts that were of shade of grey darker than the
surrounding Herring Gulls but not as dark as an Lesser Black back.   We
watched it for about 15 mins and Frank ran back to the car and got his
camera set up but it flew off just as he was zeroing in for the piccy.
Towards the end of its stay it started preening showing less
white/mirror area than other Herring Gulls but despite lifting off twice
I couldn't see the leg colour.  However, as it lifted off for the final
time I caught sight of the legs which were a striking shade of bright
yellow - but I saw them only for the merest fraction of a second.   The
bird actually reminded both of us of a Caspian Gull having an odd open
face (but not the triangular bill/forehead of Caspian) with a tiny eye
which appeared dark to us, alongside the pale irised Herring Gulls
ajacent, but to be honest the light was still so meek at 7am that it
could have had a pale iris that was just too small to see.  In flight it
had surprisingly rounded wing tips and it looked like the outermost two
primaries were still growing out (it is I believe far too late for a
michahellis to be in normal primary moult), with one larger mirror
seeming out of place higher up the primaries than it should be.  This
may well explain why it looked short winged at rest.  It also showed
clear dusky underwing secondaries and inner primaries.

Overall it was, however, a pretty strking bird.  After chasing round the
Tidal Basin etc looking for it for an hour or so (with nothing else to
report except good views of Will McPhail and Steve Hersey) I spent the
rest of the morning looking at gulls in Virginia (with good results -
see the VA list serve for details) and reckon I saw 200 adult winter
Herring Gulls at least in the course of the day and this was the only
bird I saw with a completely clean white head; so with that and the
darker mantle it really does stand out.  It might well be worth looking
for at the Tidal Basin pre-roost gathering this afternoon.

 I remembered that a bird of this sort was seen in the Blackwater area
in November and looking at the pics of that bird I would stress that
this bird looks far less chunky than that with much smaller white tips
to the primaries and a much lighter weight bill.  It does not, however,
look exactly like a classic shaped Yellow-legged Gull.  We wondered if
it was a Lesser-black back hybird of some sort but Howell and Dunn
suggests that anything of that ilk would show lots of head streaking in
winter plum.

So it's one to look out for.  I hope someone can catch up with it and
clinch the id.

Best

Gary  & Frank