I have 7 2 month old pullets in the chicken pen and 5 younger ones of varying ages and breeds in the brooder. I've tried introducing the 2 older chicks from the brooder to the chicken yard and the older pullets keep pecking them. One Buff Orpington especially goes after them. she's got the reddest comb and wattles of the other buffs. I thought maybe they had slipped a roo in with the pullets, but she has no spurs. Is it safe to leave the one month old chicks out with the 2 month chicks unattended? Will they always be picked on by the older ones? Would one of the older ones kill a young one? I'm still pretty new to all of this.