Drones vs helicopters for broad-scale animal surveys considerations for future use

Abstract

Effective monitoring is key for effective wildlife management. Aerial surveys are a proven method for monitoring medium/large-sized mammals (e.g. macropods, feral pigs) in Australia's rangelands. However, conventional aircraft are noisy, expensive, and considered an occupational safety risk for biologists. UAS (unmanned aerial systems, or drones) may offer potential safety and efficiency gains, but need to be assessed against the current best-practice techniques. We tested the ability of a long-range, fixed-wing drone (300m agl, 65-93 km h-1 , thermal and colour imaging) to survey macropod populations and validated the results against those from conventional helicopter surveys (61m agl, 93 km h-1 , human observers). Four, 80-km long transects at Roma in southwestern Queensland were surveyed and the outputs analysed using line-transect distance sampling methods. The drone was able to survey over half (56%) of the 320 km transects, and over 448 km of survey flights in total. However, the drone technique was unable to distinguish between macropod species, recorded <13% of the macropod density observed during the helicopter survey, and required more flight and data processing time. Long-range drones clearly have potential for landscape-scale wildlife monitoring but results must match or exceed the conventional techniques. Future UAS applications to wildlife monitoring require a proven ability to identify animals, a similar or greater detection probability than conventional techniques, an efficient means of data collation/analysis, and comparable costs to current-best practice survey methods. We discuss the issues for potential users to consider to ensure that new survey technologies can be used to optimal benefit.