Always keep a couple of fat friends around.

As far as food goes, there's a reason many natives died of starvation during the winter if they weren't able to stock up enough food or something happened to their caches. Getting food burns calories and if you burn more than you end up finding you'll be screwed that much sooner.

If you do find yourself lost and foodless during the winter there's a few things you can do:

1. The inner bark of many trees is edible, especially pines, firs, elms, beech, willows, maples, and basswood. Oak and cedar inner barks should be avoided.

2. Young buds of many trees, especially maple, basswood, and beech are edible.

3. Only two of the over 10,000 lichens are toxic, the rest are edible WITH PROPER PREPARATION. Lichens are very acidic and this acid must be neutralized before you can eat them. The easiest way in the woods is to boil them up with some hardwood ashes. The sodium hydroxide (lye) from the ashes will neutralize the acid.

4. Any bird is edible.

5. Pretty much any mammal you find in North America can be eaten. Mouse, vole, and chipmunk bones can be eaten after they've been boiled for a while. Like Izzy said, suck the marrow out of larger bones.

6. Pine needles tea, willow twig tea, rose hip tea, etc... They won't give you much in the way of calories but the more warm fluids you are putting into yourself the fewer calories your body needs to burn to keep warm.

Those are off the top of my head. Like I said at the beginning, you need to make sure it doesn't cost more calories to get the food than you receive from the food.

-Blast