I've had great luck with hot pepper bird seed. As they have taste buds, the squirrels hate it and leave it alone. I get it from my local Wild Birds Unlimited store.
I love the Wall of Birds! Can’t wait until COVID is over and can visit. Have seen hawks around the backyard recently. And of course daily woodpecker visitors (pileated, red-bellied, downy/hairy, and northern flickers a few times). Does anyone know why many woodpeckers (at least in the NE USA) have red patches on their heads? Why is this a common feature? And why red specifically? I can’t find any information online. Thanks, and hope everyone is safe!