I feel that the lack of him smiling works for this photograph especially when done in greyscale. The background with something cutting the middle of his head is a little distracting though. might have worked better if you moved a little more so that he's in the centre of the corridor instead. Plus the factt that his left arm is chopped off at the wrist is a little disconcerting to me.
Overall, the mood of the shot is well portrayed. In future, perhaps if he is willing to let you photograph him (and if you ever see him again), do a series of him with the birds. A more closeup shot of the birdcage with him looking at the bird or whistling to it might be interesting.
These are my thoughts. Keep shooting!