I have hand raised a brood of ten Mallard ducklings, and up until yesterday, everything was going fine. They are two and a half weeks old now, and I had noticed that one of the ten seemed to be a little 'strange' in the head i.e it was a bit slow, and every now and again it would have a 'spaz' attack (run around all of a sudden, sit down with it's head going all over the place) since it was a day old. Yesterday morning it seemed to be worse than usual, and it died that afternoon. Another one had hurt it's leg that morning, which got worse all day, and that was dead by the next morning. I have noticed that a few of the others breathe a bit heavy, and one seems to have funny turns where it stands bolt up right, starts to walk backwards, and panics. I have read on the internet that dusty, moldy hay can cause them to breath heavily, but i'm confused to what is making the act strange, and what killed the other two? Can anyone help?