I would suggest posting some samples. Post higher resolution crops of the bird, but also post a small downsized un-cropped version so we can see the relative scale of the bird in the frame (very important).
We can go round and round on what might be going on, but without samples we can only speculate.
You need to carefully analyze the images to see if anything is in focus, or to divine if focus is better behind the bird or in front. Your problem could, in principle, be technique or shutter speed, or a soft lens, or focus. First order of business is to narrow that down as best possible.