The Mob is loose!

[Pampered Hen]

I need some advice on my small flock of 6 hens.
Within the last couple weeks the girls have begund to gang up on the lowest ranking hen. Silver had always been on the bottom of the totem pole, but was an integrated part of the flock with only the occasional peck by her peers. Now, she is being pursued and harassed sometimes by 3 or more birds. No bloodshed yet, but she is in distress from the constant mobbing.
I'm letting her run free during the day so she has a chance to forage and rest as she pleases, while the other girls stay in the spacious run (100 feet of movable poultry netting). At night I let her join the flock in the coop after the mobsters have retired on their roosts. It appears the is being left in peace as long as she stays on the roost.
This kind of separation may work temporarily, but I much rather prefer her re-integration into the flock, only, I'm not sure how to go about it.

Here is some info on the flock: they all grew up together and are nearly a year old. The harassed bird appears to be in good health. We had a rooster until about 2 months ago. He was too rough on the girls backs and turned on my husband... (sadly, he is soup now...)

So, what causes the flock to turn against one of their own?
And what can be done about re-integration?

Thanks for any and all advice in advance!

 

[debilorrah]

Quote:
You are only letting her out? While the others can watch her picking at juicy bugs? And they can see her resting in the green grass, catching grasshoppers and in general having way more fun than they are?

Hmmmmm.

 

[Pampered Hen]

You are only letting her out? While the others can watch her picking at juicy bugs? And they can see her resting in the green grass, catching grasshoppers and in general having way more fun than they are?

Hmmmmm.

The "run" is as green and juicy as the rest of the garden. It is being moved around on a weekly basis. Also, the harassment began prior to letting the picked on bird run free to get a rest from the mob.​

 

[Pampered Hen]

Update: it seems the situation has calmed down and harassment has stopped for the most part.
Still wondering though what causes a shift in behavior like this?
Anybody with answers out there?