I have four new Isa Brown pullets aged 18 - 23 weeks who have been grooming each others tail feathers. They are not going for flesh, just gently pecking at the feathers as if cleaning poop off them or something. They all do it equally to each other and none seem bothered by it. No harm except a few small tail feathers look a bit raggy.
Could anyone tell me if this is normal or something to be worried about? They were strangers to each other till nine days ago when I got them from different cages at a poultry farm and put them together in my home coop. The first few days they occasionally pecked each other but seem to be good friends now.