Puffin

What I am seeing here is a need for even more value differences. Think about the blackest black on the bird. Then observe the black where the sun might be hitting it, its black but not as black as the black in the shadow, therefore it needs a lighter value of black. This will continue all the way to the white of the paper. The same gray in sunlight will have a darker value in the shadow. Also think about the form, as it rolls toward a shadow it just gets darker in value and that transition should have at least 3 value changes in it. You need many values from light to dark to create contrast, contrast creates depth and realism. Hpe this helps.