I also keep bantam cochins, and I've seen a lot of "bald" rear ends with broody hatched chicks, longer than one would expect, but they don't die. It seems really random, which makes me suspect certain hens. 
I'm glad you got an answer. I'll go back and read some of the links I skipped.
I'm glad you got an answer. I'll go back and read some of the links I skipped.
