I was at Conowingo Dam with Greg Miller, Alan Bromberg, and others. We observed the Common Gull at the base of the dam flying between the breakwater and the Harford shoreline. Greg first spotted it at 1150 and we watched it continuously until 1225 when we left with the bird still present. I have about 7.5 minutes of good video of the bird if anyone is interested in a copy. Bob Ringler