Old hens started fighting, some avoiding the coop. Help!

[Allie S.]

I recently inherited a flock of three backyard egg-laying hens (three different breeds) when a friend moved and I took over her house. They have lived here for a while and had established a pecking order before I came around. I lived here for a month and a half with no problems. Recently the two most "dominant" seeming of the three began coming up on my porch and sleeping on it instead of going into the coop like they always have, while the third hen goes into the coop and becomes very vocal at dusk.
I've seen an increased number of feathers around the yard as a result of their fighting, and a wad of them in the coop. I don't think any of them are sick as all three roam around the yard eating all day.
I don't want them sleeping on the porch and getting attacked by predators, so I shooed them into the coop and locked it and they fought with the third hen until they were asleep.
Should I be worried? Why are they re-establishing the pecking order after living together for over a year?

 

[kathyinmo]

Could there be something in the coop that they are trying to avoid? A snake, mites? Could all the feathers you are seeing be from them molting?

 

[Allie S.]

No mites that I can see. Just ants, but they're everywhere in California this time of year. It definitely seems like two of the hens are bullying the other. But the bullied hen is just so very loud, constantly clucking. No blood has been drawn, I'm just confused as why this is happening in a flock that's been established for so long.