My male zebra finch

Question
Not to long a go my pair of zebra finches layed eggs. Then one day I woke up and checked out my zebra finches and I saw my male zebra finch had a bald spot right on top of his leg, then I studied more. he is the one who is ripping out his feathers why is he doing that? I don't know what's wrong, he eating normal he playing normally and singing normally. There is no change in him? So please tell me what's going on.

Answer
It's strange he's ripping out his own feathers. He could be trying to create soft nest for his family. I would try putting torn strips of kleenex into the cage or other soft nesting material (avoid string nesting material since it can get caught in the babies' throats when the parents feed them). I personally use the Sisal Nesting Fiber that can be bought from ladygouldian.com. My own birds absolutely love it and can get quite creative with it.