The other replies have mostly covered it, but I will mention a few of the other animals, besides deer, you might hear poking around at night, just so you can see how harmless they are:

- opossums
- porcupines
- raccoons
- mice

Hearing these animals waddling around in dry leaves in the dark can trigger a quick adreneline rush that, even after you know it's 'nothing to worry about' could leave you as wide awake and fretful as if you'd been chugging espresso drinks with supper.

Over the long term, the antidote is familiarity. You learn the sounds. Now when I hear a deer in my campsite (hooves make a distinctive sound) I just tell it in an irritated voice that I'm trying to sleep and to please go away. Then I turn over and go back to sleep. <img src="/forums/images/graemlins/grin.gif" alt="" />