UAV Ad hoc Networks (UAANETs) is a subset of the well-known mobile ad hoc network (MANET) paradigm. It refers to the deployment of a swarm of small Unmanned Aerial Vehicles (UAVs) and Ground Control Stations (GCS). These UAVs collaborate in order to relay data (command and control traffic and remotely sensed data) between each other and to the Ground Control Station (GCS). Compared to other types of ad hoc networks, UAANETs have some unique features and bring several major challenges to the research community. One of these is the design of UAANET routing protocol. It must establish an efficient route between UAVs and adjust in real time to the rapidly changing topology. It must also be secured to protect the integrity of the network against malicious attackers. Security of routing protocols has been widely investigated in wired networks and MANETs, but as far as we are aware, there is no previous research paper dealing with the security features of UAANET routing protocols. This paper focuses on characteristics of UAANETs and provides a review of the literature on associated routing protocols. We also highlight the analysis of the security features of these protocols. Security requirements, potential threats and countermeasures are all described.