Sean,

I don't know if this is the same bird you saw, but there was a Ross's Gull at Indian River Inlet in DE found approx. November 15, 1996.  My recollection is the bird was observed for about 3 to 4 weeks.  It was an adult bird, retaining a fair amount of pink wash, but I don't recall the black collar being partial or complete.  I thought it was faint or absent.  Nonetheless, I remember the treat.  I believe the finders were Bruce Peterjohn and Mary Gustafson.  No surprise there, they were turning up all the good birds then.

Rick Cheicante
Harford County
Bel Air, MD