Another reason I sometimes draw in black-and-white is when I’m racing a moving target. I may yet add color to these doodles someday, but on the day I drew them, I was more concerned with jotting down each animal before it moved away. It’s a good exercise if you want a drawing challenge—or if you like being frustrated…
Twists and turns 
Land's end 
Greetings from the Best Coast 
I actually love love speed drawing. It’s frustrating, yes, but it’s freeing. unless I need it to look like something. Then I do something else.
THIS is a great sketch. I knew right away what stuff was.
and you spelled bestiary correctly!!