We currently have two flocks of chicks started. One is about 3-4 weeks old and consists of 10 chicks. The other has only 5 chicks and they are about 2 weeks old now. Recently one of our bigger chicks, Chicka, has taken to the babies. She flys over to their brooder box to join them eating, drinking, and even some snuggle time. When she feels they are ok, she will fly back to her flock in their brooder box. I was worried at first that she might hurt them because she is so much bigger, but it seems more she uses her size advantage to warm all the chicks at once. What a good big sister!