Chipmunks are fun mammals to watch in your yard. They are all over right now in New England. Generally these guys are crepuscular - that is a fancy science word for active at dawn and dusk.
Chipmunks usually eat seeds and other plant materials but may eat the occasional snail or larvae. They do store food in the fall and hibernate in the winter.
They generally make their burrows in open woodland areas or on the edges of wooded areas, but will live in suburbia as well. The entrances to their burrows are little round, two-inch holes in the ground.
If you put out bird seed on the ground, you might get a good look at a chipmunk in the morning or evening before dark.