Prior to the Spanish, Russians, or gold miners coming to California the state was filled with approximately 300,000 native people. This was a huge number compared to other states or regions. In California there are 37,000,000 people now. That's over 100 times the number of people. Back then density was one person for every 350 acres. Now it's almost one person for every three acres. People would be covering each and every acre including the year round snow covered glaciated wilderness.
Our state was as populated as it was because of the number of natural resources that existed. Most of the population was along the ocean as this offered a huge source of food. Inland populations were much lower. Let's assume that half of the population received most of their resources from the ocean. That would mean the rest of the state was living on more like 640 acres for each and every person. That's one square mile per person for the carrying capacity, and I think this is a low estimate of area required. This includes the acreage in all of the wilderness areas.
That amount of food resources don't exist today. Of course we do have different resources. There are groves of fruit trees and vineyards that are available today compared to the oaks and other species. There's less wildlife available today then there was 300 years ago. Now there're cattle and chicken farms. Fresno used to get salmon runs. Now, the river doesn't even make it from Fresno to the ocean. Dams, farming, overfishing, water contaminants, and natural causes have lowered the fish populations. (Now, don't get me wrong, I believe we need dams and farming. They are reasons for lower fish populations although I believe that water contaminants and natural causes (including seals and sea lions - let's see...1,000,000 creatures eating 15 pounds of fish each day...) are the leading causes of lower fish populations.)
If you look at food eaten by the native people you will note that what they've eaten changed over time. California used to have a large bear population as well as woolly mammoths, saber-toothed tigers, camels, and miniature horses. The native people over used many animal species and had to then hunt different, smaller species. Acorns became the staple food. If you study native populations, you will know that the native people didn't live year round in the higher elevations. Much of the areas that are wilderness today in the Sierra's were not used for anything other than tool procurement or trade. Why? Because there wasn't enough resource to support people. If there was enough resource, the populations would have been larger.
If you plan on bugging out by going into the wilderness, try it first. If this is the solution for you and your family, the most important thing for you to do is practice your skills. Go for a hike on a nice summer day. Then spend a week or two. Then don't bring any food. See how well you can survive. Then bring the family. Husband, wife, three kids… Then try it during the winter. There's a good website that gives lists of trails http://www.americantrails.org/resources/statetrails/CAstate.html. Have fun.
Me? There are too many small people that I wouldn't be able to bug out by taking a hike. We have other plans...