Weird feathers on peahen head

[Mosiek]

Can someone tell me whats is up with those feathers on back of her head? I tried to look up any informations or any othere peacock like that, but I couldn't find anything.

 

[KsKingBee]

You need to catch and do a close inspection of the area under those feathers.

 

[Mosiek]

Looks normal aka same as others, she has those feathers since before we got her and it was almost 2 years ago (she is 4 years old), her daughter has a year and don't have anything like that.