Its a pretty good illustration. Cant find much to fault about it to be honest.
Couple of things I would change, are adding some catch-lights to the eyes, as you want that to be the focal point.
Bump up your shadows a bit more, you want to be able to define form, but not overdo it.
The silhouette is very important in a work like this. I done a quick 5 minute paint-over for you to show some of the changes. I changed the tail angle to be more dynamic and to give a better read. I also tucked in under the beak to give the lines some more flow. Fluffed up the head area to give more visual interest and definition to the silhouette. Finally I added some sneaky lines to bring the focus back to the eye for a better composition feel. Minor tweaks, that you may or may not agree with. You obviously have some training and background here, considering your eye placement is on the rule of thirds intersection and the fact you done this with watercolour, a tricky medium at the best of times, so your mileage may vary on what I have to say.
Its fine as a technical illustration I think, but with images like these you tend to be not drawn in to much. Try to find ways to grab the viewer's attention a bit more. Keep up the good work, your doing great.