Broody hen attacking her own chicks..'why?

[My peeps]

Once again I need advice. I had 2 broody silkies. They shared 9 eggs. When they hatched all seemed fine. A week later I noticed them picking on the 3 black chicks. Chasing them, picking them up from their wings to move them. I kept watching them and it didn't seem constant and they didn't seem to be injured. This was the first time these two went broody. So today my husband goes out and finds the one black chick completely bloody, all feathers missing on the one side. I immediately checked the other two black chicks and they also have some feathers missing but not as bad as the one. I removed all 3. I let a friend borrow my heat lamp so I put them in an isolated part of another coop along with another hen that is raising two "teenage" birds that can be on their own. She has been a good broody so I'm hoping she will take the little ones as her own. My question. Why would the broody hens target out the 3 black chicks and leave the others alone? Oddly enough these chicks hatched from their eggs! They seem great with the other ones they hatched and the tractor supply chicks. The badly injured chick doesn't look like he will make it. I'm hoping the other 2 come around.

 

[junebuggena]

Maybe they just think they have more babies than they can manage? First time moms getting overwhelmed with all the babies?

 

[centrarchid]

Complications arising from having two hens rear a group of chicks. Remove one hen from mix and rear chicks being attacked separately.