She pecked at them until there was no skin on the heads of five them. I now know just how big an chicks eye really is. I did think maybe those six were diseased, but it seems more like she went by breeds. She's a black sex link. She decimated the California whites and the one in the best shape, so presumably the last one, was a Silver Laced Wyandotte. She left the Amerucanas alone - one of the chicks she hatched was an amerucana.
I had a similar problem in the winter with a hen (Java I think), really going after one of the white/yellow chicks, the only one of the group, until she killed it.
But this Java is amazing. I just moved the brooder outside (yes, knee surgery was last Tuesday). She could hear the chicks on the other side of the wall. I had opened the doors and she hopped in - the chicks were terrified and she started to show them how to scratch. I took out the partition and all chicks are getting on well, with the three day olds learning from the 18 day olds. And yes, I am monitoring!
Oh - I moved the ducklings to a plastic cage outside. They have low water dishes, with lettuce and spinach in teeny bits, and are just having a fabulous time.
Considering the hen, I'll leave them in their own box tonight.