A Battle Lost

There's a war going on.

It's me against the sneaky, birdseed stealing squirrels.

And so far, they have been winning.

Somehow,  those rodents manage to outwit every deterrent that I try to keep them out of the bird seed.  Even the "squirrel proof" feeders were no match for these little villains.

I've tried a homemade spray of peppermint and apple cider vinegar.  It worked for a short time, but
once the scent evaporates (or it rains) - they are right back at it.

I worry about letting the cat out onto the porch to enjoy the sun.  I know he would try to keep guard.  But I don't want him getting into a fight with a squirrel and being hurt. Or pick up fleas from one of the nasty little things.

I've heard that ultrasonic repellents can work well.  But I worry that it might also scare away the birds, which defeats the whole purpose.  I don't want to use commercial repellent sprays or powders for the same reason.  Well, that and I don't want my back porch smelling like predator pee.  EW!

Currently, I have the feeders filled with safflower seeds.  I read that the birds that usually visit my feeders - cardinals, chickadees, grosbeaks, etc - enjoy the seeds while squirrels find them bitter and unpleasant.  Unfortunately, so far the birds don't seem to be showing much interest in it either.

Do you have any tips for scaring away the squirrels, but not the birds?