I think it's mostly a case of a lack of mid tone values. the head looks amazing and you can see a lot of details but the rest of the body seemed a little flat in comparison so I added some shading to the belly similar to how you would shade spheres with a darker shadow that blended lighter. Also added a little bit of shadow to the wing to give the illusion of feathers. I wasn't too sure where the light source was supposed to come from so I just indicated my take | Artwod Feedback