I have a done a few of this scene as demonstration paintings. This one I decided to go back and rework the entire painting with palette knives. This makes it unique and more interesting as it becomes full of new color mixtures and thick textures. Knife paintings are a little harder, especially if I want details and realism, so I have to remind myself to keep it suggestive. I do use tiny brushes for the extras (like the eagle).
I wanted to use knives because of the rough texture in the rocks, which a palette knife renders very nicely.