Adding new birds to an existing (mean!) flock

[kianoosh]

I have two adult chickens, 11 month old, lovely, playful, excellent layers, and I have two 2.5 month olds. Raised all of them from 1 day olds. No rooster.

To get them introduced, I had the two young ones live next to the two older ones but separated by chicken wire, since they were 1 month old up until now. So basically two coops and two run areas attached to each other (they don't free range in the yard - city bylaw - but I do let them out when I am in the yard myself).

They are all about the same size now, but the two old ladies are still mean to the young ones chasing and pecking at them when I let them together. One can easily make the other blind or severely injured. What should I do? I really don't have space to keep two coops in my yard.

The two old ones are a cross of Rhode Island Red and Columbian Rock, and the two young ones are Columbian Rock.

 

[snow5164]

Give the little ones places to hide , make sure they all have plenty of room and wait it out . They will have to establish a pecking order. You did it right in my books, I’m waiting for my chicks to be bigger to introduce them just as you did , there will be a transition time

 

[aart]

They are all about the same size now, but the two old ladies are still mean to the young ones chasing and pecking at them when I let them together. One can easily make the other blind or severely injured. What should I do? I really don't have space to keep two coops in my yard.

Welcome to BYC....sorry you are having troubles.
You got a good start with having them side by side for a good long while.
But even then when they meet physically there will still be pecking order issues to work out.

How big is the run area they have, in feet by feet?
Pics would be a big help here too.

Here's my notes on basic integration, maybe something in there will help.
Integration Basics:
It's all about territory and resources(space/food/water).
Existing birds will almost always attack new ones to defend their resources.
Understanding chicken behaviors is essential to integrating new birds into your flock.

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.

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

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 copious blood drawn and/or new bird is not trapped/pinned down and beaten unmercilessly, 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'(but not a dead end trap) and/or up and away from any bully birds. Roosts, pallets or boards leaned up against walls or up on concrete blocks, old chairs tables, branches, logs, stumps out in the run can really help. Lots of diversion and places to 'hide' instead of bare wide open run.

 

[kianoosh]

For some reason I didn't get any notification for the updates here. Thanks @aart for the detail info. My chickens never got along since then. One of them was bullied so hard that I decided to put her out of her misery. I am replacing the entire flock this spring, and getting some less aggressive breeds.