I recently got two new chickens an americana and a Plymouth rock. My 15 wk old buffs will not associate with the rock. She will not even go into the coop with the others at night. I have to pick her up and put her in there. Then if she is on the same roost they pick her. Is this normal and will they outgrow it? I hope so cuz i feel so bad for her. The new hens are pullets but i have no idea what age. They are not laying.