I only have a Coopershawk by me, so my big chickens are cool (its funny to watch this bird with a 14" wingspan tops try to pick up one of my obese EE's) He cant even come close before they house him. My AGB hen launched herself at him when he tried to pick up her chick and even she kicked his butt). However,for my bantams and my young birds, I build an open-bottomed PVC run which is covered with chickenwire (the chickenwire is secured with zip ties. I use 3/4" PVC for these and 6" black zip ties. A 5X10' run costs me in the neighborhood of $70. Now, I just pick up my chickens in the morning and pop them in the run and then I let them out at dusk and watch over them as they make their way to their roosts, but you could probably rig some kind of door which allows them to go from the stationary run that you have now, into the moveable PVC run and then you can move them around the yard as you see fit and then let them go back into the original run at night.It's been pretty quiet today. Sixty plus posts this morning, but once I caught up with that, there hasn't been much activity.
As for the BOP on my run, it's former hunting grounds were destroyed when they built a school. I don't want it to eat my chickens, of course, but I was kind of happy to see it alive and healthy. Its nest used to be in a tree in the field. I have been worried about it. I do hope it will leave my girls alone, but I am going to have to stop their free range time now that I know the hawk is back. We have plans for a much bigger and more secure run in the spring. That one was not very well planned out but needed in a short amount of time.