Introducing new flocks to each other. Injured bird, confused.

[cupman]

I bought a 7 week old white easter egger off of craigslist yesterday. The woman was real nice and told me that the bird was 7 weeks old. I have 7 5-week old birds in a brooder in the garage. I put the new bird in to meet the others but kept a mesh barrier between them. It was like this most of the day. I normally had a different bird behind the mesh barrier due to an injury. Well I wanted to put the injured one back in the main brooder behind the mesh so I put the new 7 week old in with my 5 week olds on the other side of the mesh. They are roughly the same size, 7 week old is a tiny bit bigger but not much. This morning one of my 5 week olds was limping around the brooder. I separated her and watched the birds for awhile, no aggression at all. Do you think the new bird is responsible for the injury? I am confused I don't know whether to blame the new bird or question whether or not it happened as an accident.

Last question, at what point can I add my new birds to my 6 month old, basically full-grown flock?

 

[Pele]

I'm sorry to hear your bird is injured. To be honest though, you're moving way too quickly with them. At the very least, you should have your new bird in quarentine for at least two to three weeks to make sure it isn't sick. If it is sick, it's had contact with your flock, and you could lose everybody

Secondly, introduction of chickens is a slow process. You did the first part right, but didn't give it enough time before combining them. Give them the chance to check each other out and decide that they can live with each other. Young birds are more accepting of new flock members, but they still need a week or so of looking at em to figure out that they're ok.

The new bird probably used it's superior age and size to attack the littler one. They're complete strangers to each other, and there's nothing that chickens hate more than other chickens that are unknown to them.

I hope that helps. And the same rules will apply when you introduce the young ones as well.