You have two hens. You want to get another hen. How many hens will you have total? How many eggs will you get? What will this do to the pecking order? Show your work. You may use a calculator if necessary.
Seriously, introducing a bird* to your flock can be a process. There are several things to consider:
1) Disease: Your birds and/or their environment may have a pathogen that could kill the new bird. For example, a bird may develop immunity to one of the nine strains of coccidia (common protozoans that are nearly ubiquitous with chicken flocks) and may not have time to develop immunity if introduced suddenly to a flock with a different strain.
2) Social interaction: Birds are flock animals and hierarchy and social structure are based on the pecking order. Who’s on top, who’s on the bottom, and who’s in between is very important. Sudden disruptions to that system may lead to serious injury or death for a bird.
3) Environmental change: Birds, because they are prey species, are by nature suspicious critters, very wary of new surroundings, sights, and sounds. Some birds will starve to death rather than make a diet conversion. Others will take a while to settle in to new surroundings and may appear shell-shocked and uncertain in a new place for a week.
What to do?
When introducing a new bird to my flock, I follow these steps:
1) Vet the bird. Any new avian resident gets a check up at the avian vet. We check for and treat diseases, communicable or not, and assess the general condition of the bird.
2) Quarantine the bird. Check with your avian vet to see what quarantine period he or she recommends. During the quarantine period, the new bird will probably show signs of any subclinical illness that might be present. If this happens, repeat Step 1! If not, move on to Step 3.
3) Introduce the bird slowly to the new flock.
A. I hear you… Place the new bird in a place where it can hear the other birds but not see them. This allows the new one to get used to the sounds of the flock, and it allows the flock to get used to another bird in the area.
B. I see you… After a few days, I move the new bird’s cage so all the birds can see each other. The new bird has time to observe interactions, see its new flock, and interact more closely with them.
C. So you’re my new neighbor! Allow the bird out of the cage to interact with the other members of the flock. I usually suggest supervision for this step, and that it be done in an open area, so that if anyone needs to beat a hasty exit, it can be done.
D. Moving in! If all goes well with Step C, try caging them together. Keep a close eye out for picking around the head and eyes. If there is any sign of this, remove the picked bird immediately. This bird may have to be caged separately and may not be integrated successfully into the flock.
*Hint: It is generally easier to introduce two new birds to a flock, rather than just one. Also, it can be difficult to introduce young birds to a flock of older birds, and bantams to a flock of standard-sized birds.
If there is no picking, then congratulations! You have successfully made an avian introduction! Now put down the calculator and give yourself an A for the day!
Home to Roost 
Posted by Hen Houses on July 28, 2010 at 7:43 am
Hey,
Great post! The information is very useful and informative. Keep them coming.
Lucy
Posted by Angela Bowman on April 15, 2014 at 11:37 am
I’m curious: what about introducing a standard-sized chick to a small flock (two) of bantams? I’m worried that she would grow up to bully the smaller birds, but I’ve heard that if introduced as a chick she would grow up to respect her aunties.
Posted by chickenwoman on April 15, 2014 at 11:48 am
I’m generally cautious about introducing chicks to older birds. You’d probably end up with a dead chick.
I’d wait until she’s full size.
Posted by Angela Bowman on April 15, 2014 at 12:06 pm
Really, wow. Do you think she’d have to be fully-grown or just as big as the other birds? Because of course ultimately a standard bird would become much bigger than the bantams.
Thanks for the reply.
Posted by chickenwoman on April 15, 2014 at 12:45 pm
Right, she would be bigger than the bantams. It’s hard to say for sure. You could try introducing when she is as big as them. But I’d keep a close eye on everyone! If she is the only chick you have, it will be a bit of an adjustment to socialize with other chickens. (-: Good luck!
Posted by Audra Houser on April 17, 2017 at 10:00 pm
I have 6 grown hens, 3 Orpingtons & 3 Rhode Island Reds. One of my Orpingtons was injured pretty bad in December by an unknown source. I had brought her indoors & let her chill in a large dog kennel until she healed up. I tried to integrate Lemon Drop back into the flock with disastrous results. She was reinjured by the rooster we had. Her injuries were quite substantial (torn vent) so again she was brought inside. The rooster is no longer an issue but I’m not being very successful in moving Lemon Drop to the coop/enclosure. 2 of my hens will attack Lemon Drop if they get a chance. I let Lemon Drop outside every morning to do her chicken things & she comes back in the house at dusk every day. She will peck at the door, around 9am every morning, to come in to lay her egg. What can I do to successfully move Lemon Drop back into the flock?
Posted by chickenwoman on April 17, 2017 at 10:19 pm
Make sure she is completely healed. Then try this – take the hen on the bottom of the current pecking and put her in with Lemon Drop. Make sure they get along, and keep them together for a while. Then reintroduce the two of them together to the flock.