My 10week old chick keeps pecking!

[Tarina-Rose]

I have had my three chicks since they were three weeks old, I bought them as "guaranteed females" from a local. There haven't been any issues until one of my girls started pecking one of the others, she is only targeting one other and it has carried on for a couple of weeks. She usually runs up to her and flares her feathers up and then runs and pecks her, this is my first time with chooks so I would love some advice!
I have tried creating boredom busters and they have plenty of options for food etc.

 

[GitaBooks]

At a certain age, chicks need to establish a pecking order. In games and in dominance they will charge one another, flare their feathers, and then generally stop. If your chick is pecking them hard or pulling out feathers, these sites may help: http://www.the-chicken-chick.com/2013/03/chicken-feather-loss-cannibalism-causes.html

https://www.backyardchickens.com/a/back-to-basic-living-feather-picking-plucking-and-cannibalism

Best of luck!