Beautiful comp and exposure here. Wonderful portrait. I'd like to see it presented differently to gauge whether there's a better impact. Maybe yes, maybe no. I'd add a bit of canvas to the top and clone in the background, crop more off the right and clone out all the twigs/catkins except the one the bird is perched on. Just how I'd think of doing it, and you may not consider that much cloning/alteration ethical.
The eye/head is sharp while the body is not. But I actually like that in this case. It presents a bit of a dreamy look that's echoed with the BG.
And not to take away from this image at all. It's far better than any siskin image I have, and I have hundreds. The pose and exposure make this a winner, one I'd love to have in my portfolio.
Welcome, Agrisk
I think that you have the right idea but need to make a few adjustments in your shooting to get a sharp image. I'd definitely bump up the ISO which in turn will allow you to get more DOF and a faster shutter speed. That should solve the issue of sharpness and DOF.