I would definitely go for trapping. Although I've never trapped anything in my life, I think I could do it. I have enough survival books that I could probably pick it up pretty fast. I'm thinking some snares along a tree branch in my back yard, peanut butter as bait, and then just wait for the stupid squirrels to show up. Maybe it's harder than I think. But if I have to fall back to slingshots, air rifles and firearms, I'm all set for that too. It might not hurt to get some of those big rat traps - not the little mouse traps, but their bigger brother. That might work better for squirrels than snares. You could nail those up on tree branches pretty easily.

We have a ton of rabbits in our yard. They're quite stupid. They freeze in place when they see you. You can walk right up to them and it's like their little feet are glued to the ground. Just walk up within 3 feet (very easy to do) and throw a bath towel over them. Captured!

Our neighbors are very inconsiderate morons and their back yard is filled with a herd of yapping Chihuahuas. Their incessant barking ruins the whole neighborhood. In a survival situation, I'm thinking two birds with one stone here. Probably easier than squirrels.