Were these in a grassy / reed type of area? I've still not found any up here in the Portland area, but there was one about a year ago that was spotted (I never found 'em); The bitterns while difficult to spot, are easy to ID with the sound they make. Again nice work!
No, this was not in a grassy or reed type area. It was an open pond with several willow trees in the center. Thank you again, Chris.