Great topic, and one I have been thinking about as well. Here are a few resources:
Year-round plant use by the coastal Miwok Indians of California:
http://www.friendsofcortemaderacreek.org/cn/miwokplants.pdfAnother California harvesting calendar:
http://www.primitiveways.com/harvesting_gathering.htmlA more academic source re winter plant foods:
http://www.herbvideos.com/ewpindex.htm#west%20woodsp://
I'm thinking survival would be tough without securing sources of animal fat. Trapping and hunting suggest themselves as necessities.
For most of us medium-sized, fat-bearing critters that are easier to butcher and cook, but not life-threatening to harvest, would be the better targets unless you are desperate, experienced, etc. I'm thinking beaver, racoon, opposum, etc. over rabbits and squirrels. Otherwise bigger game like deer, bear, moose, elk, etc. would be more substantial resources.
And cooking as stew or soup instead of roasting to capture all nutrients and fat.
Thoughts?