One of the most difficult, yet essential, aspects of painting any subject is to create a contrast between light and dark. I have always struggled with achieving this effect, especially when painting birds or botanicals. Sometimes the light source isn't very distinct and I have to invent one, or I am too cautious with the dark areas, and don't want the painting to look overworked or muddy.
Now, I think I've made some progress in this area, with my latest watercolor, Kestrel. The light is cast strongly from the right side, defining the form. Another notable thing about this painting is that the bird is looking straight at us, creating more shadow away from the light. Here it is: