pretty light, and that's a cute look back pose that you are getting from the bird. I wish your shooting angle was lower. How much of a crop? I see courseness in the feathers.
I have been mutilating images for years. A tweak of sharpening technique has been made countless times. I am most recently content with Smart Sharpen: Basic, Default, 60-110%, 0.7 pix, lens blur, depending on the image (cropped). I wouldn't hesitate to back off a bit with the crop to get a little better sharpness. The shutter speed is slow enough to possibly explain why you don't have sharp detail to the base of the tail feathers.