How Many Reindeer? UAV Surveys as an Alternative to Helicopter or Ground Surveys for Estimating Population Abundance in Open Landscapes

Conservation of wildlife depends on precise and unbiased knowledge on the abundance and distribution of species. A challenge is to choose appropriate methods to obtain a sufficiently high detectability and spatial coverage matching the species characteristics and spatiotemporal use of the landscape. In remote areas, such as in the Arctic, monitoring efforts are often resource demanding and there is a need for cheap and precise alternative methods. Here, we compare an UAV pilot-survey to traditional population abundance surveys from ground and helicopter of the non-gregarious Svalbard reindeer to investigate whether small quadcopter UAVs can be an efficient alternative technology. We find that estimates of reindeer abundances from UAV imagery have lower precision and are more time consuming than present abundance surveys when used at management relevant spatial scales. We suggest that more efficient long-range fixed-wing UAVs should be evaluated for the job to increase the sampled area by UAV. In addition, the method will depend on the availability of more efficient post-processing methods including automatic animal object identification with machine learning and analytical methods that account for uncertainties.