I just happened to be looking out the back window the other day when two of the young pullets decided they no longer wanted to be in the dog kennel and flew up to the top of the six foot bar. They then perched there and then flew back into the pen. Seeing as the cats will eat anything with a heartbeat I feel the pullets are too little to be safe. So this morning we put a tarp on top of the dog kennel. It's not pretty but it will work. It will allow them access to grass and foraging which is important to their health and important to what kind of eggs they start producing for us to eat.
They are still only 13 weeks old and can't be in with the older hens (and eat the laying feed) until they are 16 weeks old. I read an article about feeding young pullets laying food too early can cause them to get too much calcium too young, which will cause unexplained deaths later in their life. Since I've have five unexplained deaths with my older hens I am following the food guidelines to a T this time round. In the evenings I round up the young gals and toss them in the hen house to roost at night and familiarize themselves with the three remaining older "laydies". I keep the food up at night so nobody is getting the wrong food. Seems to be working for now.