Several people suggested that the Bittern looks shy and is trying to hide. Actually, it is in an aerobic stretch pose with wings-up and neck-out. When they are shy and are trying to hide they usually take up an erect pose trying to blend in with the reeds. This guy/gal was actually quite accommodating. After it finished stretching it continued to forage for food. I watched it catch several frogs before it meandered off into the reeds and out of sight.