My 1week old chicks are started to jump/trying to fly. When I was looking for chicken, I used MPC's breed selecting tool and came up with "sussex is the best kind" for me. They don't fly... but they are trying now. I use guinea pig cage for brooder. When cage door is open, floor to door is about 5" high. A few of days ago, they started to try jump out but they couldn't. Now they are easily jump out and come out from cage. Today, I saw one of my chicks jump over the 1qt size feeder. When I take cover off from cage door to change food/water, they start gathering near the door. Door open then jump!!! Is that normal chick behavior????