Evaluation of an Off-the-shelf Unmanned Aircraft System for Surveying Flocks of Geese

Small off-the-shelf unmanned aircraft systems (UAS) could prove useful for surveying waterbirds. A low-end model was evaluated for surveying flocks of Canada Geese (Branta canadensis) and Snow Geese (Chen caerulescens) by comparing photographic counts from repeated flybys to repeated visual ground counts. Due to low contrast of Canada Geese with the ground, UAS counts based on confident detections only had a lower mean than ground counts for five out of six flocks (>30% lower for three flocks) and coefficients of variation (CV) ranging from 11-106%, compared to 1-6% for ground counts. Conversely, UAS counts of high-contrast Snow Geese were 60% higher on average and less variable (CV = 1-6%) than ground counts (CV = 11%). In some cases the aircraft likely detected birds that were not seen from the ground due to an obstructed view. Shortcomings of the UAS were mainly related to its unsophisticated imaging system compared to more expensive models. Otherwise, the UAS proved capable of being conveniently transported and deployed over flocks without causing them to flush. Further consideration should be given to off:the-shelf UAS for surveying waterbirds over small areas (<5-km radius) that are difficult to survey from the ground or as an option for performing low-disturbance surveys. Received 8 September 2011, accepted 17 November 2011.