How long to expect aggressive behavior towards new chickens?

[Mrsjdavis]

I have a similar issue... in trying to integrate 6 new, 2 month old chickens. They are"in the yard" with the rest of the flock which is made up of 5 ducks ( 2 drakes and 3 hens) and 7 chickens that include 2 roosters ( 1 frizzle and 1 1 Americana) and 5 hens. They are in they're own enclosure during the day so...i that everyone can get acquainted. At night they sleep in the coop, in their own large kennel. The hens don't seem to care, but if a little one gets loose, both roosters go after it , jumping on it, biting at back of their neck. Is this behavior normal? If I just supervise will they calm down? The newbies really want out to go explore the new world.