We had this problem also, and I was in tears. Actually, I was furious. I wanted to kill the little buggers. Because my dog is a mind reader, she said she would tackle this problem for me, and she did! Now i have 2 dogs and they team up and make a good game of it. Between June 1 and the end of February, Red Ryder can scare them off. I've never hit one, but they hear that sound and know they need to move out.
Some squirrels will be scared off by a radio.
This scarecrow is pretty good, too. You Just have to remember it can't distinguish friend from enemy.
https://www.amazon.com/dp/B000071NUS/
Take a look at some of the reviews for this!