Drones or unoccupied aerial vehicles are rapidly being used for a spectrum of applications, including replacing traditional occupied aircraft as a means of approaching wildlife from the air. Though less intrusive to wildlife than occupied aircraft, drones can still cause varying levels of disturbance. Policies and protocols to guide lowest-impact drone flights are most likely to succeed if considerations are derived from knowledge from scientific literature. This study examines trends in the scientific literature on using drones to approach wildlife between 2000 and 2020, specifically in relation to the type of publications, scientific journals works are published in, the purposes of drone flights reported, taxa studied, and locations of studies. From 223 publications, we observed a large increase in relevant scientific literature, the majority of which were peer-reviewed articles published across 87 scientific journals. The largest proportions of peer-reviewed research articles related to aquatic mammals or aquatic birds, and the use or trial of drone flights for conducting population surveys, animal detection or investigations of animal responses to drone flights. The largest proportion of articles were studies conducted in North America and Australia. Since animal responses to drone flights vary between taxa, populations, and geographic locations, we encourage further growth in the volume of relevant scientific literature needed to inform policies and protocols for specific taxa and/or locations, particularly where knowledge gaps exist.

Drones are a modern alternative to manned aircraft for aerial surveys, however approaching wildlife with drones may still cause disturbance. Understanding the factors influencing animal responses to drone flights is fundamental for informing guidance on lowest-impact flight practices. We reviewed scientific literature on drone flights conducted to approach wildlife and collated and quantified references to factors that should be considered in the development of guidelines and policies. The most referenced controllable factors were approach distance, noise emissions and airspeed. Other frequently referenced controllable factors included drone type, take-off distance, flight pattern, pilot experience and competence, whether consecutive flights were conducted and flight duration. The most referenced environmental factors were animal taxa, biological state of animals and ambient noise, followed by whether conspecifics are present, weather variables, habitat variables, whether animals have received previous exposure to anthropogenic settings, animals’ behaviour prior to drone flights and whether predators are present. Policies and protocols that address these factors have an increased probability of minimising disturbance of drone flights. The variability in animal responses across different taxa, different ways drone flights are performed and the different circumstances they are deployed in highlights the need for taxa-specific protocols that also account for geographical and biological variations.