Well, this little beauty was a challenge. There were two principle difficulties: the beak and the feathers (could more succinctly be referred to as "everything" - ha!).
The complex pattern of light and dark values in the beak defeated me. So I flipped his photo upside down on my iPad and my gessoed board likewise and painted the jigsaw of darks and lights upside down. When I turned the painting the right way up, I had a beak - puckering up. Phew.
Then, for his lovely soft featheriness, I realised that I was not able to paint this effect in a single sitting. I painted some dark barring in thin paint and left it to dry, then applied soft feathery strokes using a comber brush and thin greyed down white paint the next day.
Photo uploaded to Paint My Photo by Robyn (Ro) Lovelock - thanks, Ro!