Everyone pecks at the polish heads

[griffin4]

I have a mix of hens but it seems everyone likes pecking the heads of the polish hens and rooster. They are not over crowded or otherwise aggressive but all of the polish have the feather pecked off just the tops of their heads. We tried the Vaseline gooped on the heads but the others seem to enjoy the taste :/ What can I put on them to stop the pecking that is not toxic?

 

[sourland]

Sadly enough Polish in a mixed flock very frequently have their crests pecked. I'm not sure there is an effective solution other than free ranging or a separate run.