Dear All

With apologies for a slightly belated post I wanted to report an interesting gull 
seen in flight over Washington DC two days ago, on Tuesday 2nd January.  All 
the identification marks pointed to this bird being a California Gull, however, 
the sighting was too brief to clinch it for certain.  With luck it will hang around 
and someone might get a confirmed id.

The bird was seen from my office in flight with three adult Ring-billed Gulls and 
flew past at top-of-building level down Rhode Island past the Audubon office 
on Connecticut & M St heading westwards at about 3pm.  I first picked it up 
flying directly towards me as it looked longer-winged and more rangey than 
the Ring-billeds, probably 10-15% larger than the accompanying Ringers, with 
notably proportionately narrower wings especially in the basal third.  It looked 
more W-shaped in overall shape.  The bird flew past me, along with the 
Ringers, down light giving views that were mostly of the underside. 

The bird, probably a subadult I think, showed clean white underparts and grey 
upperside to the wings and mantle. The key points were:

- the extent of black on the wing tips was much greater that the Adult Ring-
billeds and seemed greater in extent than 2nd yr Ringers (which I know well), 
forming a distinct wedge-shaped triangle on the underside of the primaries.  
There was only one white mirror visible which was small and as far as I could 
see was near (but not at) the tip of the outermost primary and only visible on 
the upper surface of the wing.  There appeared to be no white tips to the 
other primaries although the views of the upperside of the primaries were poor.

- the tone of grey on the upperside was significantly darker than the adult 
Ringers and darker than European Common Gull (which I also know well), akin 
in tone to a Laughing Gull but much richer in colouration and less cold in 
appearance. 
  
- the nape, ear coverts and sides of the breast in the pectoral area were 
heavily lined with rich, warm ochre-brown spots which extended in a narrow 
band across the upper breast and throat to form a necklace

Otherwise the bird was not notably marked.  It showed no tail band that I 
could discern (although this might might not have been visible from the 
underside).  The bill was very similar in size and shape to the Ring-billeds, 
yellow with a dark ill-defined subterminal band.  

The bird was in view for about 45 seconds and whilst it looked very interesting 
I was stumped as to an id at the time.  Not being either mindful of or familiar 
with California Gull I may well have failed to note critical features.  It was only 
on consulting Sibley and talking to colleagues that this possible id emerged.  

I would appreciate comments and advice (offlist if preferred) and would flag 
this bird for people to keep an eye out for at places like Georgetown Res or 
the Potomac in central DC.  

Cheers

Gary