From southern Queensland, my post would relate to southern US states. I did some tests some years ago which gave interesting results
http://www.lrrd.org/lrrd21/7/simo21105.htm
One flyer as far as the chooks are concerned is South African boxthorn (Lycium ferocissimum). The birds will eat anything on it with relish. Leaves, fruits, the lot. You never see a dead leaf under the bush. The plant copes with all soils, drought, frost, the lot.
