Take my advice for what you want, I’m in no way shape or form a bird photographer. Don’t bother manual focussing on fast moving things like birds, even if they are sitting still. You are never going to do a better job than your camera focussing, especially with a crop camera. As for getting it sharper, just stop down, I don’t know what aperture you used since you stripped the exif. The second way to get it sharper is obviously a better lens, I’m not sure what you are using at the moment.