Feather Problem!

[awesome124]

My silver laced wyandotte is at the bottom of the pecking order, but she pecks and eats the feathers of my Jersey giant and buff orpingtons. The other chickens stand still as she pecks their feathers. I know and see that all of the other chickens peck her but never her feathers. Why is my silver laced wyandotte pecking and eating feathers, and how can I stop her? Also, why aren't my other chickens defending themselves?

Any advice would be greatly appreciated
THANKS