Evaluating Alternative Flight Plans in Thermal Drone Wildlife Surveys—Simulation Study

Abstract

The rapidly developing technology of unmanned aerial vehicles (drones) extends to the availability of aerial surveys for wildlife research and management. However, regulations limiting drone operations to visual line of sight (VLOS) seriously affect the design of surveys, as flight paths must be concentrated within small sampling blocks. Such a design is inferior to spatially unrestricted randomized designs available if operations beyond visual line of sight (BVLOS) are allowed. We used computer simulations to assess whether the VLOS rule affects the accuracy and precision of wildlife density estimates derived from drone collected data. We tested two alternative flight plans (VLOS vs. BVLOS) in simulated surveys of low-, medium- and high-density populations of a hypothetical ungulate species with three levels of effort (one to three repetitions). The population density was estimated using the ratio estimate and distance sampling method. The observed differences in the accuracy and precision of estimates from the VLOS and BVLOS surveys were relatively small and negligible. Only in the case of the low-density population (2 ind./100 ha) surveyed once was the VLOS design inferior to BVLOS, delivering biased and less precise estimates. These results show that while the VLOS regulations complicate survey logistics and interfere with random survey design, the quality of derived estimates does not have to be compromised. We advise testing alternative survey variants with the aid of computer simulations to achieve reliable estimates while minimizing survey costs.

Analysis of the Possibility of Using Unmanned Aerial Vehicles and Thermovision for the Stocktaking of Big Game

“…The use of unmanned aerial vehicles for game inventory is an area of interest for many major research centers in Poland (Witczuk et al, 2018), (Witczuk et al, 2021) and around the world (Gonzalez et al, 2016). These studies mainly concern the accuracy of methods using thermal imaging, the possibility of recognizing animals with the use of artificial intelligence methods, etc.…”

Animal detection using thermal imaging and a UAV

“…Unmanned aerial vehicles (UAVs) are increasingly frequently used in nature research. The use of such machines is often safer, more cost-efficient and less time-consuming compared with the use of manned aircraft traditionally used for nature inventory (McEvoy, 2016;Wich and Pin, 2018). It is noteworthy that even economical equipment can be applied for nature inventory related tasks.…”

“…To achieve this point, it was necessary to design an aircraft capable of operating at a wide range of angles of attack (Rodzewicz et al, 2018). UAV's missions can be effective provided if performed properlyscientists should correctly choose the size, shape and configuration of the aircraft and pay attention to altitude, speed, direction and flight limits in such a way as to minimize stress for wild animals (Drever et al, 2015;Junda et al, 2016;McEvoy et al, 2016;Wich and Pin, 2018). When designing or selecting a UAV to perform a given task, designers should take into account not only their aerodynamics and performance but also its compactness.…”

“…Therefore, artificial animals having cameras in their eyes are often used to maximally decrease the anxiety of filmed species [1]. When planning the mission, legal restrictions are also relevant, as they complicate the research in terms of logistics (Witczuk and Pagacz, 2021).…”