Thank you all, I have a new baby chicken that my Australorps have mothered from scratch. Amazing how 3 can take care of and share this new addition. I find my Hylines aggressive when a new chicken is added into the existing group.
New chickens need to be added slowly and carefully to the flock using the "look but don't touch" method. There is a good article at https://poultrykeeper.com/general-chickens/introducing-new-chickens/ explaining how to do it.
