I admire your photography, but I get the impression you couldn't get very close to the squirell, try laying out some sunflower seeds and disguising yourself as a marionberry bush, thats how I do all my great squirell shots.
IMO, the squirrel doesn't seem to be the strong point of the pic (without the title, I probably would have missed it). Perhaps some post-processing in Photoshop would help to emphasize it.
The squirrel is in decent focus, but the colors in this photo are kind of drab. Certainly, there's not much you can do about repainting the building :-) But I think that this kind of shot with a more interesting background would do better. I like the composition of the squirrel being at the upper left.
I think the squirrel is too hard to notice. The colors of the image and him are too close. Still, thought that capturing the squirrel was pretty neat. They do move fast.