Food football! Give them some fruit like pear halves or apple halves--something they can take in thier beaks and run around with. They will snatch it wayay from each other.
Also, if you happen to have some wood with pill bugs in it, they can eat the bugs. (lay some untreated wood on the ground for a while untill it gets damp and icky on the bottom. The bugs will come! )
And if you let some weeds or tall grass grow in a corner, they can play hide and seek or ferociosu jungle chicken or whatever they do in there. Mine love weeds.