Use of Drones With Thermal Infrared to Locate White‐tailed Deer Neonates for Capture

Abstract

ABSTRACTDrones are growing in popularity and are used to locate individual animals, estimate ungulate population size, and monitor endangered species. Our goal was to assess the efficacy of using drones to locate neonatal white‐tailed deer (Odocoileus virginianus) for capture. During May–June 2019 and June 2020, we used a drone equipped with thermal‐infrared (TIR) and conventional multispectral red‐green‐blue (RGB) cameras to locate and confirm fawn thermal signatures in Minnesota's southern farmland region. We confirmed 29 and 71 fawn thermal signatures in 2019 and 2020, respectively. We captured 13 fawns to validate the methodology (detection and identification) of using drones for capture in 2019. We flew the drone for 47.3 hours covering 792 hectares (17 hectares per hour) in 2019 and flew for 41.1 hours and covered 1640 hectares (40 hectares per hour) in 2020. We worked 201.5 person‐hours with a mean crew size of 4 people that required 6.9 person‐hours to locate each fawn in 2019, whereas we worked 145.7 person‐hours with a mean crew size of 4 people that required 70% less effort and resulted in 2.1 person‐hours to locate each fawn in 2020. Flight efficiency was highest at 60 m above ground level (AGL) with a speed of 9 m/s; however, diurnal use of drones made identifying fawn thermal signatures difficult as thermal loading of the environment quickly reduced the temperature differential between vegetation and signatures. We found TIR‐equipped drones to be an efficient method to locate and subsequently capture fawns in open habitats in comparison to other capture methods such as vaginal implant transmitters (VITs), ground searches, or monitoring doe behavior. We recommend flying at night or in cloudy conditions to avoid false positives. © 2021 The Wildlife Society.