I find that squirrels have a lot more time in a day to try to figure out how to get to food, than I have to try to prevent them.
If I stop the squirrels, its more interesting to the bunnies, so then they join in to try.
If the bunnies try, then it becomes a competition with the chipmunks and ground hogs.
Within a week I have a deer in my yard claiming victory over all the tiny animals that aren't as great and majestic, while standing over the hole that used to be my special plant.