An experimental approach to evaluate the potential of drones in terrestrial mammal research: a gregarious ungulate as a study model

Abstract

Research on the use of unmanned aircraft systems (UAS) in wildlife has made remarkable progress recently. Few studies to date have experimentally evaluated the effect of UAS on animals and have usually focused primarily on aquatic fauna. In terrestrial open arid ecosystems, with relatively good visibility to detect animals but little environmental noise, there should be a trade-off between flying the UAS at high height above ground level (AGL) to limit the disturbance of animals and flying low enough to maintain count precision. In addition, body size or social aggregation of species can also affect the ability to detect animals from the air and their response to the UAS approach. To address this gap, we used a gregarious ungulate, the guanaco ( Lama guanicoe ), as a study model. Based on three types of experimental flights, we demonstrated that (i) the likelihood of miscounting guanacos in images increases with UAS height, but only for offspring and (ii) higher height AGL and lower UAS speed reduce disturbance, except for large groups, which always reacted. Our results call into question mostly indirect and observational previous evidence that terrestrial mammals are more tolerant to UAS than other species and highlight the need for experimental and species-specific studies before using UAS methods.

An experimental approach to exploring the feasibility of unmanned aerial vehicle and thermal imaging in terrestrial and arboreal mammals research

“…This action may occur in wild populations that have been exposed to human presence for a long time, for example, by human tourism activities around their habitat [23]. However, our study shows that the behavioral changes that occur are not that significant, compared to studies conducted on guanacos [24]. This research suspects that the size of the type of UAV used provides a different level of interference.…”

Possibility of applying unmanned aerial vehicle and thermal imaging in several canopy cover class for wildlife monitoring – preliminary results

“…The author found that drones with a flying altitude of < 50 m HAGL were good for detecting and recognizing animals. However, flying at lower altitudes takes longer flight time to survey the same area and increases the risk of disturbing the animals [1]. Increasing detection by lowering the drone's height certainly has implications for increasing the sound emitted by drone engines.…”

“…drones) are capable of moving fast, scanning forests from top to bottom and are very promising for expanding the scale of canopy surveys that are very useful in studying wildlife ecology. Drone imagery has proven useful for wildlife surveys in open areas, for example, guanaco [1], Artic birds [2], kangaroo [3], caribou [4], waterfowl [5], hippos [6], and crocodile [7]. Meanwhile, for animals living in tree canopies, UAVs are not widely used because of the difficulty of visually detecting these animals with standard aerial imagery.…”

Behavioural synchronization in a multilevel society of feral horses

“…New technologies enable more wide ranging and accurate data collection in societies with hundreds of individuals (Charpentier et al, 2021; Inoue et al, 2019; Schroeder et al, 2020). For instance, our use of drones succeed in obtaining positional and behavioural data of more than a hundred of feral horses in Portugal, which formed multilevel society with a two-layered structure with units—a group of individuals which stayed closer than 11.5m more than 70% of the time—and a herd—an aggregation of units (Maeda et al, 2021).…”