This experiment is a combination of frame-by-frame animation and keyframe animation. Here's how I did it:
First step was to study the anatomy of an ermine! I was already familiar with the anatomy and movement of a cat, so I used that knowledge and converted it to sketch out a simple run cycle of an ermine:
I added these sketches into Photoshop and used them as a base for my digital animation. I added in some inbetweens and ended up with this guy!
Next step was the surroundings. I like the digital paper collage style a lot, so I printed out my background images, crumpled them up and put them back under the scanner. I also masked out some of the smaller components I'd be using.
Then some magic in After Effects and we've got a moving background!