Naughty hen

Hi. I am a new chicken mama. have two 8 month old Isa brown hens and five 14 week old assorted chicks, all pullets.
About a week ago, i put the babies in the coop with the big girls.
Now before that, I had the little ones in a run next to the big girls for almost a month and a half, thinking they could look, but not touch.
After introducing them to each other, one of the hens, Agatha, has been pretty aggressive. I expect some pecking and chasing to happen, but I am afraid she will kill one. A few times, she has cornered one of the babies and grabbed either a chunk of feathers on a wing, or at the base of the neck, and at the same time, jumps up, and with her claws, tries to claw them, if that makes sense. She will not stop. I have been told that this is not normal, and I don't know what to do. I have separated her a few times, and she has yet to sleep in the coop with the others because of her aggression and my fear of what I will find in the morning.
She is a very sweet chicken to us, and I can see she is lonely without her sister, the other 8 month old.
What am I to do???

The problem is the age of your older ones, they are not quite old enough to accept young ones, they haven't matured enough to think chicks are a normal thing to show up, I would keep the older one penned inside your coop for a while, in a separation pen while the young ones get comfortable, you can keep her sister with her if you want, and you can let everyone out while you're there to play referee, it's best to let the younger ones get comfortable in the coop than add the big ones back in, I'm assuming your coop is big enough, and you should make sure that everyone has some sort of escape, under, on top of, something to run around. Patience and a bit of time.

My coop is only 4x8, with a large run. There are no hiding spots inside the coop, which is why I am so nervous. I have been keeping the bossy hen in the brooder box in our basement. There is plenty of room for her, but I am not sure how long I have to keep her separated at night. Her sister is great with the little ones, and they get along fine. Its just Agatha. Also, when I let Agatha out to free range with the others, penny, her sister, isn't as nice to the chicks.

Can you make her a pen inside the pen or run, or put her in the pen your little ones were in, you can add escape things into the run if the coop is too small, eventually it should work out, just take things slowly, the bigger the chicks get the less you should worry, and an occasional peck to young chicks is quite normal, so is a bit of chasing, cornering and causing real harm is not normal. It can take a bit of time.

Here's some notes I've taken on integration that I found to be very helpful.......
......take what applies or might help and ignore the rest.
See if any of them, or the links provided at the bottom, might offer some tips that will assist you in your situation:

Integration of new chickens into flock.

Consider medical quarantine:
BYC Medical Quarantine Article
Poultry Biosecurity
BYC 'medical quarantine' search

Confine new birds within sight but physically segregated from older/existing birds for several weeks, so they can see and get used to each other but not physically interact. Integrating new birds of equal size works best.

For smaller chicks I used a large wire dog crate right in the coop for the smallers. I removed the crate door and put up a piece of wire fencing over the opening and bent up one corner just enough for the smallers to fit thru but the biggers could not. Feed and water inside the crate for the smallers. Make sure the smallers know how to get in and out of the crate opening before exposing them to the olders. this worked out great for me, by the time the crate was too small for the them to roost in there(about 3 weeks), they had pretty much integrated themselves to the olders.

If you have too many smallers to fit in a crate you can partition off part of the coop with a wire wall and make the same openings for smallers escape.


The more space, the better. Birds will peck to establish dominance, the pecked bird needs space to get away. As long as there's no blood drawn and/or new bird is not trapped/pinned down, let them work it out. Every time you interfere or remove new birds, they'll have to start the pecking order thing all over again.

Multiple feed/water stations. Dominance issues are most often carried out over sustenance, more stations lessens the frequency of that issue.

Places for the new birds to hide out of line of sight and/or up and away from any bully birds.

In adjacent runs, spread scratch grains along the dividing mesh, best of mesh is just big enough for birds to stick their head thru, so they get used to eating together.

Another option, if possible, is to put all birds in a new coop and run, this takes the territoriality issues away.

Read up on integration..... BYC advanced search>titles only>integration
This is good place to start reading:
https://www.backyardchickens.com/a/adding-to-your-flock