It really isn't a good thing to let the bird sit on a nest for weeks, if she is not going to hatch eggs. They are not eating or drinking properly. They are not getting the exercise they need. The proper and humane thing to do, is to set up a broody cage and snap the bird out of it, fast as possible. I know what you are talking about with the weird behaviour. One of my broodies will get all ruffled up when I pull her off the nest and set her on the floor, she'll just sit there and growl. Set up a broody cage. You can do a search and see that is what is done.
Jack
Jack
