Use of small unmanned aerial systems for sharp-tailed grouse lek surveys

Manned, aerial surveys are an important tool for wildlife managers, but they are dangerous to conduct, expensive and difficult to replicate. Interest is increasing in using small unmanned aerial systems [sUAS] due to concerns associated with traditional manned, aerial surveys. To assess the potential of sUAS technology for grouse lek surveys, we examined the behavioral response of sharp-tailed grouse Tympanucus phasianellus to a quadcopter sUAS platform in the Northern Great Plains. We conducted 43 surveys at 19 leks between 9 April and 3 May in 2018 and 2019. We found altitude and wind speed were informative at explaining the behavioral response of grouse following sUAS exposure. We observed an increase in flush responses during low altitude surveys (≤30 m above ground level) during periods of low to high wind speeds. In contrast, flush responses were mitigated when survey altitude increased to 121 m above ground level with moderate wind speeds. Further investigation into sUAS for lek surveys should explore altitudes >121 m above ground level, using more advanced sUAS platforms.