It will just take some time. I'd say, leave them up for a few months if you have to (with winter coming, they will be looking for food). But, they should show up eventually.
I think our attack was a freak accident (we had two juvenille doves that weren't as fearful as they should have been). Some hawks or other birds of prey do eat birds, but in the couple years I've been feeding, this has only happened once. We have a kite, three types of hawks, and an owl pair. So, with those odds, I think that was a rare occurrence. We've never lost a squirrel either.
