Missing Feathers on Backs

[NHchickenflock]

We were recently given 12 chickens from a friend who was moving.
When we picked them up I would say about 10 are missing tail feathers and feathers on their backs.
I looked and did not see any lice or fleas.
They were all kept together with about 10 others in a pretty small coop.
What may cause this?
Can it be passed to my other chickens?
What will help the feathers grow back?

Thanks in advanced!

 

[NHchickenflock]

 

[cash money]

It is caused by being too crowded and chickens love blood if one is bleeding it will get pecked which backed it bleed more or they get to bored and just peck

 

[NHchickenflock]

Anything I can do to fix the problem?
Our coop is much bigger so it shouldn't be a size issue now.

 

[cash money]

Keep there attention else where other than each other do you let them free range at all

 

[cash money]

Try and find ways to get there attention of each other and there fethers should be back in a couple of weeks

 

[NHchickenflock]

I wasn't sure if I could free range them yet as they were just moved into this coop at our house today.
Anything else we can do?
I was told something about a blue dye for their skin so the others don't notice as much.

 

[cash money]

I put that on there back and then a piece of duck tape so if the other chickens still peck they can't hit the new fethers the tape will come off in about 3 weeks

 

[cash money]

And when the tape comes off if there's a piece hanging take it of so the chickens don't get curious and pull at it which might cause more damage to the fethers

 

[NHchickenflock]

What is it? The dye?
Where can we find it?