Squirrels... the wild game that can meet your survival needs. Squirrels are a great animal to have around in a survival situation. For a number of factors that many other animals fall short on.
Abundance/Availability. Squirrels of one species or another can be found just about everywhere. Squirrels unlike deer are able to sustain higher levels of hunting pressure without being wiped out. They are high in protein, are easier to hunt than most other game species and are easy to clean and process.
Hunting squirrels with a rifle or shotgun can be as simple as aim and shoot. I would encourage you, however, to put away the gun and focus more on traps or primitive weapons as guns make noise and ammo is finite. Letting anyone in earshot of you know where you are and that you have a weapon that they want is not exactly something you will want to do in a SHTF situation.
That said, most squirrels live in trees and have small home ranges. So they aren't really going to go anywhere if you fail in your hunting attempt. They will be in the same area only hiding for a few minutes before resuming their food searching activities.
They are day creatures too, which is a huge advantage for us if we want to hunt them. Most mammals are nighttime creatures that move mostly after dark when hunting them can be impossible unless there is a clear sky and a full moon.
So don't forget the lowly squirrel when the SHTF.
Dirrections on how to
clean a squirrel.