I have acquired three new hens to add to my flock. I officially have 5 hens and one very timid rooster. Timid, that is until the newbies arrived last night. As of this morning my roo is very aggressive with the new hens and he's trying to mate with them. They are very young (about 16 weeks old). The other two hens that we had are also very aggressive with the babies. So my question comes in many parts: 1) How old should a hen be before my rooster mounts them to mate; 2) Is it normal for my other two hens to be aggressive with the new babies; 3) If it is normal.... how long will this last? 4) I obviously need to be watching for the physical welfare of the chickens, is there anything that I can do in order to facilitate a smooth transition? Thanks for helping.
The pullets should be old enough to not be injured by the roo. It's perfectly normal for the established flock to be battling with the newcomers. They are re-establishing the pecking order. It will likely stop in a week or two. The flock should be fully integrated in a month or so.
I would have integrated much more slowly, but my flock is also much larger. Doing it slowly I have found to be the key to successful integrations. It also tends to lead to fewer all-out-battles. That way there is some squabbling, but fewer actual fights.