I have fed the birds for a few years, squirrels got 98 percent of it, there were dozens. I don't mind, I saved baby squirrels from a roomates cat and raised them, feeding them formula through a syringe then nuts and releasing them in spring, it was late in the year in the north I saved them.

Anyway, they all disappeared. I use no poison, neither do my neighbors, no one is shooting them, some predator just murdered like two dozen squirrels in my backyard. 100 yards away there are a few left. Pine Martin, perhaps an owl, idk.