Light plays a large role as to how the subject will look in a photograph. You only have to look at the mountains with the first or the last light of the day and compare that with middle of the day light. I also find it interesting when on a cloudy day, light breaks through and highlight a subject. Same goes when ray of light breaks through the forest and light up a flower. With birds I most often prefer light coming from behind me and showing all the beautiful colours it hold. But it can be fun when the bird is not fully under the direct light. As in the attached picture, light and lack of makes the Boreal Chickadee look like a 10 gram bully.
Until next moment,
Amar