Can anyone help me with this?

[Eggcessive]

The light is just one of the many possible causes. A gamecam in the coop, or spending some extra time with them to see who might be doing the picking, could be helpful. Pinless peepers are something that some people use, and they can prevent them from seeing the victim to help avert pecking. Once you narrow down the suspect, it might be worth trying.

 

[jamacare]

So, I know who the culprit is: the dominant brown is the "Top Hen" among the six birds (4 brown and 2 black). I am reticent to do the whole trim the beak thing, but if it comes to it... Hope to avoid that.

 

[jamacare]

So I cleaned the hens backside with warm soapy water (body wash), pat dried it, and slathered the region with A&D. The top flap of the vent did have some dried blood/scabbing which I did not remove, but did clean. I hope this helps her out.

 

[Eggcessive]

Glad that you have narrowed it down. I would get some pinless peepers before even considering trimming the upper beak. I think that @sourland and a few others may have more advice on them. They are applied to the nostrils. Apparently the chicken can see to eat and drink and get around normally, but they just keep them from aiming and pecking on a victim. Here is some info:
https://www.eggcartons.com/Pinless-Peepers-p/article-1.htm

 

[hayley3]

Glad that you have narrowed it down. I would get some pinless peepers before even considering trimming the upper beak. I think that @sourland and a few others may have more advice on them. They are applied to the nostrils. Apparently the chicken can see to eat and drink and get around normally, but they just keep them from aiming and pecking on a victim. Here is some info:
https://www.eggcartons.com/Pinless-Peepers-p/article-1.htm

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