I honestly don't know much about bird anatomy and such so this will be difficult but here goes...
I notice the paper you used, Was this just a little sketch? If so my first comment makes more sense. Your pencil is too blunt. It's difficult to work the right details and tones into your work if you don't have a sharp pencil. It also helps you be more accurate about where you place your strokes.
The bird looks pretty good. You have a nice texture happening for the feathers but perhaps a reference would help improve the realism. A trick is to make the strokes follow the contours of the shape. this means that because the bird's head is "spherical" the lines could have curved over the surface and added more of a realism.
Probably another thing that let you down is the lack of light source. The whole image is shades of grey. You have no dark shadow and no light which would have helped the image read better. For instance you could have used those tones to emphasise what's bird and what's tree.
The tree is good. There's not much to say about trees. I like the texture of the bark. Though perhaps it's a little too uniform? Some bark could have been wider than others, And some branches could have started earlier or curved uniquely. Also I assume that's a flower on the bottom branch? It blends in with the leaves a bit. Use contrast to make things stand out.
All in all a good picture that could have been executed a little better. Still great work, keep it up.
As usual take my critiques with a grain of sand. (Also sorry for the star ratings... It's not a unique concept...?)