UAV wildlife radiotelemetry: System and methods of localization

Abstract

The majority of bird and bat species are incapable of carrying tags that transmit their position to satellites. Given fundamental power requirements for such communication, burdened mass guidelines and battery technology, this constraint necessitates the continued use of very high frequency (VHF) radio beacons. As such, efforts should be made to mitigate their primary deficiencies: detection range, localization time and localization accuracy. The integration of a radiotelemetry system with an unmanned aerial vehicle (UAV) could significantly improve the capacity for data collection from VHF tags. We present a UAV‐integrated radiotelemetry system that relies on open source hardware and software. Localization methods, including signal processing, bearing estimation based on principal component analysis, localization techniques and test results, are discussed. Using a low‐power beacon applicable for bats and small birds, testing showed that the improved vantage of the UAV‐radiotelemetry system (UAV‐RT) provided significantly higher received signal power compared to the low‐level flights (maximum range beyond 1.4 km). Flight testing of localization methods showed median bearing errors between 2.3° and 6.8°, with localization errors of between 5% and 14% of the distance to the tag. In a direct comparison to an experienced radiotelemetry user, the UAV‐RT system provided bearing and localization estimates with 53% less error. This paper introduces the core functionality and use methods of the UAV‐RT system, while presenting baseline localization performance metrics. An associated website hosts plans for assembly and software installation. The methods of UAV‐RT use for tag detection will be further developed in future works. For both the detection and localization problems, the mobility of a flying asset drastically reduces tracker time requirements. A 7‐min flight would be sufficient to collect five equally spaced bearing estimates over a 1‐km transect. The use of a software‐defined radio on the UAV‐RT system will allow for the simultaneous detection and localization of multiple tags.

A Comprehensive Overview of Technologies for Species and Habitat Monitoring and Conservation

“…VHF tracking is labor intensive (it might take a day to locate an animal) and has limited coverage (a few hundred meters around smaller tags). Drone-based VHF triangulation has been trialed to avoid the difficulties of manual radio tracking (Cliff et al 2018 , Shafer et al 2019 ). Automated triangulation can be performed with fixed receivers (e.g., Kays et al 2011 ).…”

Enhancing monitoring of rewilding progress through wildlife tracking and remote sensing

“…Wildlife tracking technology can also be prohibitively expensive, especially with the need to acquire many devices to track a big number of individuals. Fortunately, high-resolution satellite imagery and wildlife tracking technology are becoming increasingly cheap, accessible and high quality [64][65][66][67]. Technological developments are facilitating an increasingly high spatio-temporal resolution to our combined wildlife tracking-remote sensing approach to monitor rewilding progress.…”

A bespoke low‐cost system for radio tracking animals using multi‐rotor and fixed‐wing unmanned aerial vehicles

“…Firstly, there has been very limited testing on animals, with tagging to date almost exclusively restricted to avian species (Cliff, Fitch, Sukkarieh, Saunders, & Heinsohn, 2015; Tremblay, Desrochers, Aubry, Pace, & Bird, 2017). Furthermore, many studies are limited to single tag testing (Bayram, Stefas, & Isler, 2018; Dos Santos et al., 2014; Körner et al., 2010; Shafer et al, 2019), and thus, their ability to track movements when multiple animals are tagged remains unknown. Furthermore, none of the studies have utilized or tested their systems on fixed‐wing UAVs.…”

“…Recently, researchers have begun to explore the potential benefits of UAV-based radio tracking systems (hereon referred to as UAVRTS) compared to conventional methods. However, as Shafer, Vega, Rothfus, and Flikkema (2019) note, many of the presented systems exist primarily as proof-of-principle concepts. The prime focus in most of these studies is the refinement of the localization methods employed.…”