Whilst browsing art books, I came upon some paintings by watercolorist Skip Lawrence in which he defined his subjects by painting their shadows only. It was a very interesting effect, and really drew the eye into and around the paintings.
Watercolor Shadow Bear
Since our bear is basically one big blob of shadow, the fun of the effect is somewhat lost. I can see trying this again someday in the distant future when my life no longer contains a bear a day.