Today around 4:00 pm I saw a flock of gulls at Centennial Lake.  About 
half of them were Ring-billed, and the others were small gulls with 
black or black-and-white heads.  I thought maybe Bonaparte's, but Sibley 
says "Bonaparte's rarely mixes with larger species, but Black-headed 
often consorts with Laughing and Ring-billed Gulls."

I have posted 10 photos at this URL:
http://tinyurl.com/5fup4

Unfortunately, the photos are poor.  Partly this was due to shooting in 
the rain, and partly because just as I was getting closer to the gulls 
for some better pictures, a group of people came along and scared away 
the birds.  I got a few photos of the gulls in flight while they 
circled, then they were gone.

I'm quite curious to know what I saw, so I hope ID is possible from the 
pictures.  By the way, these photos were cropped only; no effort was 
made to improve them by photo editing.

-- 
June Tveekrem
Columbia, Howard Co, MD
tweekiebird AT toadmail DOT com