Thank you to everyone who has given me ideas about the Schoolhouse Pond 
gull.  First, one correction from my earlier post:  it was a 4th year gull, not 3rd 
cycle.  All aspects of the plumage indicated an adult bird except for the 
amount of black in the wingtips and the small amount of black in the spread 
tail.  The bill, mantle, scapulars, coverts and tertials were all consistent with 
an adult or 4th year gull.

Second, many of the messages I got suggested a Lesser Black-backed Gull X 
Herring hybrid.  I agree that based on what I saw and described that a 
possible hybrid can not be ruled out.  Part of the reason that I hesitated 
regarding this earlier was the color of the legs.  Other possible LBBG X Herring 
hybrids that I have seen have had a distinct yellowish tint or wash to the 
legs.  Today's gull had distinctly pink legs, with no hint of yellow.  However, 
when I checked the Gulls of the Americas book by Howell and Dunn, they 
describe the leg color of suspected hybrids as ranging from "flesh to yellowish 
flesh legs".  Photos H7.1 and H7.2 on page 294 also show a presumed adult 
LBBG X Herring hybrid as having a pinkish cast to the legs, which is obvious in 
the photos.  So, given variation and possible backcrosses, it is definitely a 
possibility.  The primary extension seemed short for a LBBG with the tail 
extended to P7 or P8, but this could be within the variation expected for a 
possible hybrid.

Thanks again for the ideas and input.  I haven't had this much fun at the pond 
since the "Nelson's" Gull showed up in February under similar weather 
conditions.  And, the Iceland Gull was nice too.

Fred Shaffer
Patuxent MOS