I have 24 two week old chicks, Buff, RIR and Wyandottes. I have them in a brooder that is 24" deep, 4'x4' with a screen door on top. The last couple of days they have been having a contest to see which one could fly the highest. If not for the door on top, they would be able to fly out, as they have flown up and hit the door and lamps several times. Is this normal? They can't be trying to escape, they have all the feed, water and heat they need.