Quote:
Extend your posts with something firm, a piece of pipe, wood, etc. by about 6 in. Then string, tightly, three strands of plain wire(the kind you would use for electric fencing) at about 2 in. intervals along your six inch extension. Chickens will not perch upon something so flimsy or something they cannot visualize...they may attempt to hop up to the former fence top and this wire will deflect their ascension plans. Make sure you do it on the gates as well and any flat surface onto which they can hop. Full size birds will not fly over a visualized obstruction just to get to the other side, so they are hopping to the top of your fenceline and then dropping down to the other side.
If six inches isn't enough, extend it to 8 or 10. This is the only way I've found to keep determined birds inside perimeter fencing of large areas.
Any thick fence posts need to have the same treatment....they are very good at finding hop points. Don't give up....most folks have this problem when they free range within a perimeter fence.