Does anyone know of a homemade squirrel repellent that isn't harmful to birds? I'd like to use it on the top of the bird feeder.

The squirrels are not only eating out of the bird feeder but they're tearing it up too. It wasn't even out there three days before they gnawed a hole in it. The feeder is hanging from a tree branch. The quirrels climb down the twine rope that the feeder hangs from. I can tell that it's not an easy task for them to get that bird seed. The feeder is lightweight and when the squirrels get on it the whole thing swings and spins. One of them lost their balance and fell off this morning. It was funny until I found out they put a third hole in the feeder.