The prospect of integrating new chickens into an existing flock is always nerve-wracking, whether they're 8 weeks old or 8 months old. The main concern is that the two groups of chickens will not get along. However, it is possible to introduce new chickens to a different group of birds without drama or bloodshed. Integrating new chickens into an existing flock does not have to be stressful for the chicken keeper or the chickens.
I use an approach to flock integration that I call the "Playpen Method." I have used it successfully with each addition to my flock over the years. The Playpen Method is simple: allow the newbies and the original flock members to see and hear each other without having physical contact for a reasonable period of time. This allows both groups to familiarize themselves with one another while maintaining a "safe zone" for the new chickens. Integrating new flock members should be done slowly in order to minimize the stress on everyone.
The Playpen Method entails creating a confinement system ("playpen") for the newbies in the vicinity of the flock. This can mean that the flock remains in the run with a small, separate playpen near or in the run for the newbies. It can also mean that the flock free-ranges with the newbies in a playpen nearby.
I have used several different playpens for my newbies but the technique is always the same: look but don't touch. After the confinement period of approximately a week, provide the newbies with an opening from the playpen to venture out at their leisure. They will stay close to the playpen and maintain a safe distance from the flock initially, but eventually they will become comfortable and begin mingling freely.
Here are a few of the Playpens I have used over time:
These three, 8 week old Bantam Cochin Frizzles were the first addition to my original flock. The pen was a rudimentary chicken wire and tomato stake enclosure that I put near the run. Obviously, water and feed should be made available to the birds in the playpen at all times.
Here are Monica, Rachael and Phoebe in the new chicken tractor my husband built.
This set-up was originally intended as a maternity ward for my broody hen but it has been used as a playpen ever since.
The flock checking out the residents, as intended:
I hatched two different groups of chicks a few weeks apart and wanted the Littles to have a chance to spread their wings for a few days before letting them play with the big chicks. It's safer that way and the older chicks became caretakers of the babies soon after being brought together. Hardware cloth inserted in the middle of the brooder provided proximity and safety for everyone.
With the construction of my new coop completed, I put a temporary playpen in the corner, which can be removed easily. This is the ideal set-up for the Playpen Method as the newbies are trained to know that the coop is home and they will always return to it at dusk.
This shows the removable top of the playpen in the Little Deuce Coop.
It keeps the flighty flock members out and the newbies in.
The dog kennel below is subdivided for two different age groups of chickens. The 'teenage' chickens will reside here for a week until being moved to the grow-out coop next door.
When they are moved, I will close off the nest boxes for the first week or two, which will prevent anyone from hiding or sleeping in them and teach them to sleep on roosts as they should. When chickens get into the habit of sleeping in nest boxes they soil the nesting material where eggs will be laid. Good coop management leads to clean eggs.
Newbies whose playpen is NOT in the coop, are put in the playpen every morning and returned to the brooder at night until I'm certain they're reasonably comfortable with the flock. It's a little tricky to get them to understand the concept of going into the coop at night, however, as they have not been trained to the coop yet. When they are placed into the coop full-time, they will be confined to the coop itself for a week or so in order to reinforce the new bedtime routine. Again, close off the nest boxes as described above to discourage sleeping and pooping in them.
Some minor conflict is to be expected as the established pecking order is rearranged. However, if there is any persistent bullying or bloodshed, remove the victim from the general population immediately, clean their wounds and keep them segregated until they are fully healed. This is necessary for their own safety. If the victim is bullied upon her return to the flock, separate the bully in a playpen for a few days, after which she should play nicer with the other kids.