Why are my 2 hens attacking eachother

Do you have an existing flock or are those your new starter chickens? The fighting is normal since they have to establish a new pecking order. It takes about a week until they fight it out.

Don't know if i'd leave mama and the babies in the same pen unless they're already used to living that way. chickens can be very aggressive towards the baby-chicks and sometimes even kill them.

I would say she is letting that other hen know to stay away from her chicks. If the other hen can't get away from the chicks, this will probably continue. I agree with an earlier post about separating your hen with the chicks from the other chickens if possible. Your mother-hen obviously feels threatened. And roosters can be bad about killing chicks also. At some point, when you do integrate them, there will be fighting until a pecking order is established.

Quote:

Originally Posted by Baruch 

No. There are 2 hens that are fighting. The mother hen is fighting the hen.

i got that... that's why you should give mama and babychicks their own space.

Are they free range hens or are they in some type of enclosure? If they're in an enclosed area, how big is it? It sounds to me like the rooster has taken the "alpha" position, and the mother hen is the "beta"; I think the mother hen is just making sure the other hen realizes she last in the pecking order. Fighting among the flock is normal, especially when the flock is in new surroundings or a new chicken is introduced. Even if the other hen is just standing there, the mother hen will still feel like her position is possibly being challenged, and she's even more protective because of the babies. If you separate the babies and put them in a brooding box, she will probably calm down, then you can reintroduce the babies back to the flock when they're big enough.