Might the absence of birds be connected somehow to the anti-zika spraying? Even if the spray didn't directly harm birds, if it interfered with the food chain there might have been an impact... I really hope I'm wrong.
Birds here are recently much more numerous - I think the onset of colder weather encourages them to visit the feeders. I've also noticed quite a few birds investigating the nesting boxes - I thought they wouldn't do that until early spring, but perhaps it's to find a warm place for the winter?
I've decided I need a bat house... does anyone else have one, and do you have any tips on how to encourage bats?