Question At what age & or size should the new chicks be before adding them to the coop and the other full grown 2 year old chickens? How do I add them to my flock without them being attacked by the older chickens?
Answer Never introduce baby chicks to a flock of older chickens. Chickens should be introduced once they are fully feathered and half grown. Once your chickens have reached the age of 12 weeks or so you can start the process of introducing your pullets to your flock.
I usually put the chicks in their own small pen inside the coop at night so that the older chicks can see them and get used to them but can’t hurt them. If you don’t have enough room in your coop to do this then try putting them inside a cardboard box or a small dog kennel in the coop at night so the older hens don’t feel like they are being invaded.
The more room you have the easier it will be so make sure that there are enough nesting boxes and room to roost for your new hens when you first let them into the main coop. It is important for the older hens to see the young ones over a period of time, without them being able to get at them.
You also can, if you have the room, construct a small pen next to the main run with a box or shelter of some description. You need to leave them there for a couple of weeks then when you do introduce them you may need to do it gradually for a few hours per day so it is the least traumatic as possible for all concerned. A pecking order will be formed and this is the most peaceful way of doing it.
Some people have added their new hens to the coop at night while the other hens are roosting. I haven’t tried this but many claim that this is a successful way to add new chickens. The chickens wake up in the morning with the new chickens and think that they are part of the flock and accept them.
You can also construct an area where the younger smaller hens can escape to and where the larger hens can’t access. Take it slowly and you will be fine.