Integrating chicks into existing flock

[IslaBean]

About a month ago, I adopted five month old chicks off Craigslist. The man who had them had got them from a farm, but decided he didn’t want to keep them anymore. The chicks are in a small enclosure in my garage right now. They are getting big and I want to move them into the coop during the day. My girls are free range and I was hoping that I could let the little chicks use their coop during the day while the big chickens are out and about. However, my only concern is that I might get my existing flock sick by letting the chicks use their coop. I’m not sure about the health of my chicks since I don’t know much about their background. The chicks seem pretty healthy. Do you guys think that since they’ve made it 9 weeks, I can assume they’re healthy? Do you think that the chicks could have an underlying sickness that I don’t know about that could get my girls sick?

 

[azygous]

It's always a possibility that you will be importing an avian virus with these new chickens. Chickens can be carriers and not show symptoms. The odds in favor of this happening is even greater with chickens from a private source, and before that, they came from yet another private source, making it even more of a possibility.

 

[RWise]

Can they see each other now? I place mine where they can see but not touch. Then after some time, I move them at night (easier for me) to the main coop, for me the younger I can get them there the better, mine went to the main coop at 5 weeks old.

 

[IslaBean]

Are they old enough to fully integrate?

 

[IslaBean]

They are still so much smaller than the rest, I’m worried they’ll get hurt

 

[RWise]

A hen will have her chicks in the flock at 2-3 days old. I put mine in at 5 weeks old with the flock. Just look at this proud guy standing in the chicks,,,



And as for the hens/pullets there is a pecking order and they figure it out fast. Some of my girls will stand in there group and all is well, the old gal, they move away from.
Edit; also what you dont see is an area surrounded with 3"x3" fence for the little one to eat in, and get away from all the big birds.

 

[aart]

I integrate chicks young.
Brood them in the coop at about 1 week after hatch,
then start integration at 3-4 weeks.
But I have set it up to be easy.
https://www.backyardchickens.com/articles/integrating-new-birds-at-4-weeks-old.72603/

I hatch all mine here, I do not bring in birds from the outside.
So you must consider biological/medical quarantine:
BYC Medical Quarantine Article
BYC 'quarantine' search

..and then follow
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.