Estimating Wildlife Tag Location Errors from a VHF Receiver Mounted on a Drone

Abstract

Recent studies have demonstrated the high potential of drones as tools to facilitate wildlife radio-tracking in rugged, difficult-to-access terrain. Without estimates of accuracy, however, data obtained from receivers attached to drones will be of limited use. We estimated transmitter location errors from a drone-borne VHF (very high frequency) receiver in a hilly and dense boreal forest in southern Québec, Canada. Transmitters and the drone-borne receiver were part of the Motus radio-tracking system, a collaborative network designed to study animal movements at local to continental scales. We placed five transmitters at fixed locations, 1-2 m above ground, and flew a quadrotor drone over them along linear segments, at distances to transmitters ranging from 20 m to 534 m. Signal strength was highest with transmitters with antennae pointing upwards, and lowest with transmitters with horizontal antennae. Based on drone positions with maximum signal strength, mean location error was 134 m (range 44-278 m, n = 17). Estimating peak signal strength against drone GPS coordinates with quadratic, least-squares regressions led to lower location error (mean = 94 m, range 15-275 m, n = 10) but with frequent loss of data due to statistical estimation problems. We conclude that accuracy in this system was insufficient for high-precision purposes such as finding nests. However, in the absence of a dense array of fixed receivers, the use of drone-borne Motus receivers may be a cost-effective way to augment the quantity and quality of data, relative to deploying personnel in difficult-to-access terrain.

A Review of Marking and Tagging Methods for Blue Catfish, Channel Catfish, and Flathead Catfish

“…Another relatively new technology that may increase efficiency includes the use of GPS transmitters and unmanned aircraft systems (Crossin et al 2017;Desrochers et al 2018;Mathis 2018).…”

A standardized protocol for reporting methods when using drones for wildlife research

“…While many applications of drones involve the acquisition of imagery, other payloads also have been used for wildlife-related applications, including acoustic sensors (Wilson et al 2017;Fu et al 2018), biological sample collectors (Pirotta et al 2017), radio telemetry receivers (Cliff et al 2018;Desrochers et al 2018), and bait dispensers (Johnston et al 2016). Use this section to briefly describe the type(s) of data collected with the drone or the main function of the payload.…”

Where did the finch go? Insights from radio telemetry of the medium ground finch (Geospiza fortis)

“…For example, we were unable to find the nest of the individual LF1234 (but see Figure A9 ). This limitation could be overcome using drones equipped with an antenna to track finches and with an onboard camera to film the location of the nest (Desrochers et al, 2018 ). A second limitation was the labor‐intensive task of tracking finches with portable antennas in variable, but generally harsh, climatic conditions.…”