So I was very surprised when I found what is almost certainly a different LAGU x RBGU yesterday in Tinley Park, Illinois. While scanning the local Ring-billed flock for leg bands, I caught a dark-winged bird with a partial hood out of the corner of my eye. I automatically assumed I had a sub-adult Laughing Gull, but then I began to process the orangy bill and leg color, as well as a faded hood (as opposed to a molting hood) - a pattern always exhibited by this suspected hybrid combination.
|Putative Laughing x Ring-billed (adult). Tinley Park, IL. 22 May 2015.|
For what it's worth, I've not seen the Chicago bird this season despite having checked 5-6 times since late March.
EDIT: I relocated the Chicago hybrid on 24 May 2015 and photos confirm two different individuals.