I couldn't believe it when I saw this so I had to grab my camcorder. One of my males challenging the other for his cave, never seen it before or since and they have loads of caves to choose from. Don't worry neither were harmed and peace was quickly restored.
http://www.youtube.com/watch?v=Cc-65S7ugmE
http://www.youtube.com/watch?v=Cc-65S7ugmE