I've done further research for my climb animation sequence. I considered further the emotional state of the old man and felt as though he would be angry and at a breaking point. He's foolish to be chasing a squirrel into a tree. I felt like he's got to a point where an animalistic nature is taking hold of him. I figured that if he portrayed the characteristics of an animal, he might act like a tiger. Big cats are comfortable climbing trees. They have grace and raw strength. They are very wild and instinctual. I found some amazing reference of tigers climbing trees, attacking and growling. One thing I'm interested in is their paws, the way they use them.
I've done 7 pages of thumbnails for the man and the squirrel!
This first page here I did while putting together the camera moves and animatic (leica reel.) I was considering appealing and revealing camera angles and staging issues.
 When the skeleton of my scene is figured out, I start thumbnailing emotionally. I create very rough and simple doodles of my characters taking the shapes and poses that I feel could convey their emotional state.
 So then I get more analytical about emotion and physicality. I studied the way that big cats move and started to break that down.
 I'll definitely write down as well as doodle ideas and thoughts to get organised and get all my ideas out. I do believe that drawing this way is a snowball process; it brings more ideas when you see a visual.
 some squirrel gestures:
 big cat jump and attack:

Now it's time to start rough animation blocking!