I think that hardly any of us have any idea what "self sustaining" means, and that the majority of us (myself included) would fare very poorly if we tried to live off the land for any length of time.

Given that my garden this year produced less than 1/4 of what I expected and that winter is coming, if I knew I had to feed my family this winter and I had no supply of local food, I'd pack what I have now and get out of the area - head south where it's warm.

Migration has always been a coping mechanism for survival.