They do groom each other, and it can turn into feather picking. Like bearded birds can lose their beards and muffs from overzealous grooming, but if you watch it as it happens, you will see them standing still and letting the others pick off their faces. Or roosters can get their faces and necks picked from their hens grooming in the same fashion.I had been wondering if chickens ever groom each other, or if it’s always assumed to be feather picking.