Hen molting issue

aart said:

Welcome to BYC!

You have an integration issue...her being gone from the flock turned her into a 'stranger' when you put her back in.
Chickens don't like strangers and will defend their resources(space and feed/water) vehemently,
sometimes drawing blood and/or causing serious injury.
Why she was 'picked on' to begin with needs to be resolved.

Lack of space(crowding) is often a reason for feather picking.
Lack of protein can also play a role.

Telling us more about your coop/run sizes(feet by feet) might help someone give you a suggestion for a solution.


Meanwhile........
Here's some notes I've taken on integration that I found to be very helpful.......
......take what applies or might help and ignore the rest.
See if any of them, or the links provided at the bottom, might offer some tips that will assist you in your situation:
 
Integration of new chickens into flock.

Consider medical quarantine:
BYC Medical Quarantine Article
Poultry Biosecurity
BYC 'medical quarantine' search

It's about territory and resources(space/food/water). Existing birds will almost always attack new ones.
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. Integrating new birds of equal size works best.
 
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 blood drawn and/or new bird is not trapped/pinned down, 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 and/or up and away from any bully birds.

In adjacent runs, spread scratch grains along the dividing mesh, best of mesh is just big enough for birds to stick their head thru, so they get used to eating together.

Another option, if possible, is to put all birds in a new coop and run, this takes the territoriality issues away.

For smaller chicks I used a large wire dog crate right in the coop for the smallers. I removed the crate door and put up a piece of wire fencing over the opening and bent up one corner just enough for the smallers to fit thru but the biggers could not. Feed and water inside the crate for the smallers. Make sure the smallers know how to get in and out of the crate opening before exposing them to the olders. this worked out great for me, by the time the crate was too small for the them to roost in there(about 3 weeks), they had pretty much integrated themselves to the olders. If you have too many smallers to fit in a crate you can partition off part of the coop with a wire wall and make the same openings for smallers escape.

Best example ever of chick respite and doors by azygous 
https://www.backyardchickens.com/t/1069595/introducing-chicks-to-adults#post_16276224


Read up on integration.....  BYC advanced search>titles only>integration
This is good place to start reading:
https://www.backyardchickens.com/a/adding-to-your-flock

Click to expand...

KissellChickens said:

Extremely helpful information! Our coop that houses 6 (currently 5 due to removal of said hen) is about 12 sqft. The run is about twice that size. One waterer, one feeder, one roost, and three nesting boxes. I read that 2-3 sq ft per hen is sufficient in space. Does breed typically have anything to do with it? I know Rhode Island reds can be broody and they seem to be the main territorial ones. I suppose I'll do my research and read up on the suggested links. Hopefully our new chicks will adapt. Their coop and pen is parallel to the current one, with only some welded wire spectating both runs. Would post a photo but the mobile uploaded doesn't seem to be working.

I really appreciate the info and advice!

Click to expand...

aart said:

According to whom...the manufacturers and farm stores employees that want to sell cute coops to inexperienced beginners?!?!?
Sorry, pet peeve of many here...grrr...sigh...shm. Not your fault, many fall into this error...so many stories.

That coop and run is good for about 3 birds ...max....and that is probably the problem you are having ....they are very crowded, makes em cranky.
Where are you going to put all those chicks?!

Good article on Space linked in my signature...take a look at it.

Click to expand...