I encounter a lot of these on my walks:
I think they are quite territorial because they often make a very distinct and very loud chirping sound - and this particular fella wasn't shy at all when I passed by. I always thought they were chipmunks, but I believe I am wrong. I think they are actually a type of squirrel - specifically, a Douglas squirrel. But from seeing images of chipmunks, I have definitely also encountered these on my walks as well (now I need to photograph one to prove it...).
