I’ve had a bird feeder for quite a few years now hanging in the same spot of the same tree the whole time. It was only until 4 days ago that I decided to refill it with birdseed. Since then, I haven’t seen one single bird, only an occasional squirrel. What can I do to attract birds? I was thinking that since I’ve kept the bird feeder there unfilled they might have habituated to it. Should I change the position?