Beautiful detail and color. Like the open bill . the angling away of the perch helps. I would prefer a longer transition of in focus to out of focus w regards to the perch even though it would then be more obvious that it is a a rail. I presume no clipping in the yellows of the head. Overall great image
I like the singing pose. Good colours too. The rail is minized by the thin DOF and doesn't look half bad as a diagonal like this (but I know what you mean as I'd prefer something else too). I eliminate the dark band along the bottom edge of the frame, as well as the small OOF dot below the rump.