Maran cuivres - fliers?

Hi,

I have a Maran Cuivre (copper maran) who has decided to become an escape artist by flying from the top of the coop to perch on the 6ft fence surrounding their outer run. She's about 18 weeks old, just about at POL. I think I want to clip her flight feathers. Question now becomes: one side or both, and is she old enough?

Yes, as Joyfull said, clip one wing. You should find that as she grows and gets heavier she will fly a lot less.