I think cats may be the reason for bird decline at my feeders. I've spotted a cat hiding in dense shrubbery in our side yard twice in the past couple of months and another time, a large cat was sitting up in an oak tree! My husband was out with the dogs last night and said there was a black cat in the yard but it took off when it spotted the dogs! The cats I've seen appear to be beautiful, well fed cats so I don't think it's a feral cat issue but rather neighbors who allow their cats to be outdoors.
I can't blame the kitties; it's a normal instinct for them to go after birds.
It's the owners who are irresponsible, allowing their cats to roam free ... not safe for the songbirds but also not safe for the cats who can be hit by cars or taken by coyotes, etc.
