A week ago I sat for a couple of hours by a small freshwater wetland trying to coax an Australian Reed Warbler into clear view, but it was having none of it. Played calls on my phone and it had a lovely conversation but was only ever going to peek at me through the Typha reeds, just like this.
1DX II 600mm f4 III 1.4x III 840mm HH
1/2000 f8 iso 800
Cropped from horizontal and a bit of S&H and light sharpening.
Manual
There are plenty of problems here but I'm sure you are aware of them yourself. There are one speces of Reed Warbler here in Sweden to that I still haven't got a decent frame of so I know what you are trying to achieve...