We have a small backyard flock. 3 hen's and 1 rooster. Today I added 2 new hens. It has not gone over well. The old hen's do not accept the new ones and attack them. Is this unusual? Will it pass as they get aquainted? Actually, one of the new ones has been killed, don't know if it was the chickens or our dogs that did it, and the other one hides under a bush all the time. Does any one have any suggestions? I didn't know chickens did this.