Wood Pidgeon Close Up

Well! Today,not being completely happy with the results from my D800 and Big Sig combination,I thought it a good time to do some research and the try some different settings.It was suggested that because of the sensitivity of the sensor you need to keep the camera more steady than usual as it is more prone to 'movement'?
So here is a shot to see the results?

Nikon D800 +Sigma 150-500 O/S @500mm,1/250 @ F6.3 in FX mode,using the full sensor size and post cropping on PC.And a JPEG file so as not to corrupt the file!