Thoreau writes in his journal:
I see where probably a red squirrel had scratched along over the snow, and in one place a very perfect and delicate print of his feet. His five toes in separate sharp triangles distinctly raying off, or often only four visible. In one place I find a beaten track from a hole in the ground to [a] walnut a rod distant up which they have gone for nuts, which still hang on it. The whole
print of the foot, etc., is about an inch and three quarters long, a part of the leg being impressed. Two of the tracks, when they are running, apparently, the two foremost, are wider apart and perhaps with one pair.