On about 4 acres of property we have maybe 400' of black tubing 1/2" (5/8"?) running above ground over often rocky terrain. We live in the Sierra foothills at 2700' and rabbits, deer, and some other animals like to pierce the the 1/2" tubing and the smaller 1/8" drip lines. It's mostly done where the lines run through bushes. I guess they like to munch on something while they are hiding under the shade. Burying the line is a consideration, but it's hard work even with a medium trencher because of the many underground rocks. PVC might be the best bet. Perhaps 3/4" PVC main lines and 1/4" PVC (if it's made) over the smaller lines. However, it might be good to have some flexibility as already provided by the drip lines. Maybe there's something else that can be done. Comments?