This is one of my latest personal projects, an attempt to diversify and strengthen my illustration portfolio. So I decided to make a series of illustrations for covers of four books that are somehow visually based on different animals - The Pigeon by Patrick Süskind, Watership Down by Richard Adams, Black Beauty by Anna Sewell, and On the Origin of the Species by Charles Darwin.
Here's a look at the process, from sketch, to illustration and book cover mock-up.