try including some exif data, im finding myself wanting to know what aperture/shutter you have used etc.. lordson is right, that little bit of camera shake makes the whole image look soft and while this may be hard, next time try to fill the frame even more to cut out some of that background, i often find a plain background can work really wel with some pictures so its not necessarily a bad thing.
It is no longer easy to firmly handhold 1/100 sec when you are at 283mm zoom, JayJay. You shook, albeit a teensy-weensy bit. But for the real experts on bird photography (check out our member Raymond J Barlow!), a good photo is a TACK SHARP one.
As to the uniform background ... I don't mind that one here at all, for we can better focus on the fact that the bird is feeding on this bit of grain.