In 2007 I was at the Nuremberg Zoo in Germany. This is me with Fritz. He's their silverback.(He has an outdoor space, too.)
It's hard to draw animals - they never stay still. Even when they're sleeping they don't hold a pose for longer than a minute. I start lots of different gesture sketches and if I wait long enough eventually the animal will cycle back through to the same pose and I can keep drawing.
These are pages from my sketch book. I used pigma Micron pens and sketched the gorillas at the Toledo Zoo in 2008. At the time I used sketching as a way to understand animal anatomy, but when I did a finished drawing I worked from photos.
This is Fritz - from a photo - drawn in pencil on 140 lb. hot pressed watercolor paper.