I want to thank everyone for their responses re possible candidates for my alleged Chestnut-Sided Warbler hearing at Hughes Hollow over the weekend. The overwhelming favorite suspect was Yellow Warbler. I did hear several Yellow's in the same area, and had convinced myself that that was indeed the bird I had heard. As I was preparing a retraction based on over enthusiasm, I received an off-list email indicating that a CS Warbler was seen in that location. The moral of the story, "Tromp through the mud until you see the dang bird!"
 
I do sincerely appreciate all of the feedback. 
 
Ray Wickline
Washington, DC
Germantown, MD