I have an active bluebird nest in my garden. A chickadee tried, unsuccessfully, to take it over. I read somewhere that I could place another box nearby, and the chickadee and bluebird would nest in near proximity. So, I grabbed another bluebird box from my garage and put it in my garden about 50 feet from the active bluebird nest, without a hole reducer.
The chickadees are very interested in it. However, as soon as they come anywhere near it, the male bluebird swoops in and chases them away. No one is building a nest in the 2nd box; the bluebird won't allow it. Does anyone know how far away this second box would need to be from the active bluebird nest for the bluebird to stop protecting it?