Even adding Gaussian blur to the background doesn't sort it,it still looks like it landed next to a wall of stubble, I think its sadly the background itself that's the issue.
It looks to me like the ground dips beyond the bird then rises, the flattening effect of the telephoto then makes it look like its closer than it is, especially with it being tonally quite close to the foreground colour, so in essence there is nothing there to give the impression of depth to the image.