Behavioural responses of adult and young White Storks Ciconia ciconia in nests to an unmanned aerial vehicle

Due to their falling cost, unmanned aerial vehicles, often called drones, are increasingly used as a tool in bird research and conservation. However, behavioural responses of birds to flying drones are still not well understood, for example do birds recognize drones as predators, as benign, or as neutral elements? How do they read to drones? We answered these questions and described the behaviour of birds toward drones during a study with White Stork Ciconia ciconia in north-eastern Poland. We used a small quadrocopter and noted flight initiation distances (FID) of adult storks on nests and behavioural reactions of their young towards drones. During nest inspections by drone, adult White Storks showed FIDs of between 1 and 20 metres, but occasionally did not even flush during drone approaches. FID was mainly affected by breeding stage, but some storks even ignored the working drones close to the nest (14%). Birds that escaped from the nest at the egg stage, returned to it on average within 23 seconds. The most common reactions of young White Storks to the drone were scaring (42%) and akinesis (34%). The rapid return of adult storks to the nest, even when scared away, shows that drones are not an highly invasive tool for examining their breeding outputs, even during the most sensitive period, i.e. egg stage. We believe that drones will soon become an important and common tool in research of the White Stork for determining breeding success and examining nests for hazards, e.g. waste, strings or electrocution risk. Our research can be a useful guide to researchers for predicting stork behaviour during inspection of their nests in the near future.