Our squirrels love our bird feeders, and they persistently try to reach the bird seed and nuts. If there's a way to the feeders, they'll find it.
I enjoy watching the acrobatic antics of our squirrels trying to climb or jump to the feeders, and I don't begrudge them some of the bird food, but once they figure out how to get to the food, it's gone in no time.
So why not give the squirrels their own feeders, stocked with their favorite food? That way, they're happy, and I'm happy watching them, while the birds get more of their bird food.
Just be sure to place these squirrel feeders well away from bird feeders and your house!