I have 3 BSL that are 9 weeks old and 6 others that are 4 weeks old (2 white rocks, 2 barred, 2 RIR). They are the first in my flock. Today was the first day that I put them together for a little bit to meet each other. The 3 older chicks are noticeably larger and seemed to peck at the smaller ones a little. It wasn't too much but I stayed out there with them and it wasn't a long time. Is this normal behavior and should I continue introducing them on pretty days or wait until the size is closer? Also could I possibly leave them alone during the day and kennel the small ones at night or is it too soon?