I have a pair of hens, that fostered a gouldian chick for me.
But today I found one of the hens badly plucked and bleeding.

She was plucked and bleeding in the right neck and shoulder area. I cleaned her off and put her in a private hospital cage.
This is the second time that this hen has been bloodied by her buddy. And it will be the last, as they are not going to be put together again. And this is unfortunate, as I had planned to keep this pair of hens as fosters, since they raised the gouldian chick. But not if the dominate hen will be this aggressive to the other hen.
They had been sitting on eggs, and I'm thinking that her buddy was frustrated that the eggs have not hatched, and took out her frustration on her.
I have seen males fight, but I have never seen blood in the male cages, like I have seen with this hen.