Now that I uploaded it, I can see I didn't do so well but basically the easiest way would be to use the quick selection tool (inversed) before attempting to clone out the dark area so you don't accidently lose the thin dark border that you want to keep. Decreasing the opacity of the clone tool and using maybe screen mode would work well. Where I messed up was that I used the blur tool to slightly blend the shades better so they appear more evenly like the left side of the bird. Using the Gaussian Blur works much better at around 2.5 or less pixels.