Paul is hiking on an established, marked trail in the mountains. Donald is cutting trees a few hundred feet higher, but directly above Paul. As a prank, Donald rolls a small rock toward Paul. The rock gains momentum and soon dislodges other rocks. The falling rocks trip Paul and as he is losing his footing, Paul scrambles to grab a tree branch for a handhold and in doing so Paul injures his shoulder.

Question: Discuss the potential torts (torts, not crimes) for which Donald might be liable and any possible defenses to these torts.