Estuary Stingray (Dasyatis fluviorum) Behaviour Does Not Change in Response to Drone Altitude

Abstract

The use of drones to study the behaviours of marine animals is increasing, yet the potential effects of drones on natural behaviours are poorly understood. Here, we assessed if a small consumer drone produced behavioural changes in a ray common to New South Wales, Australia, the estuary stingray (Dasyatis fluviorum). A drone was flown directly above a total of 50 individual stingrays, the altitude above that ray was progressively reduced, and any behavioural changes were recorded. While stingrays demonstrated a range of behaviours, these behaviours rarely changed during drone observations (n = 6 or 12% of flights), and no change in the type of behaviour or number of behavioural changes was observed as the altitude decreased. These results suggest that consumer drones have little visible impact on stingray behaviour but do not exclude potential physiological responses. As a result, we recommend that when conducting drone-based stingray research, operators fly at the highest altitude possible that allows monitoring of features of interest, and we conclude that drones are effective tools for assessing natural stingray behaviours.