Eric - there is an interesting and little known tidbit about the groundhogs of February 2nd.
They are a recent (1800's?) "americanization" of an old northern european tradition - watching the bears at season's tide.
Early peoples knew and admired the bear. We could learn from bear what foods to eat - useful herbs as well.
And the bear's magical ability to "die" each winter, to be reborn in the spring was inspirational.
The theory of the shadow comes from the idea, that if the bear saw her shadow on that first emergence of early spring, then the work of purification - the cleansing of the bear's spirit - was not complete, and the bear would re-enter the little death to finish it up.
The groundhog is not quite up to the task...