The use of drones to study the breeding productivity of Whooper Swan Cygnus cygnus

Abstract This research was carried out in north-eastern Poland, where Whooper Swan Cygnus cygnus is a sparse breeder. Whooper Swan is timid and exhibits a tendency to hide in emergent vegetation. A drone was used to improve the effectiveness of research into its breeding success and offspring productivity. The breeding density of Whooper Swan in the study area in 2022 was 10 pairs/100 km2. The number of breeding birds detected at the beginning of the breeding season did not differ according to the method used (drone vs ground). The breeding productivity of the sample of swans studied (N = 36) was 2.19 cygnets per breeding pair using the ground method, but 3.71 per pair with the drone, a significant difference (p-value of the Wilcoxon test = 0.0148). The traditional method showed that 50% of the pairs had bred successfully, whereas with the drone this figure was 79%. The birds either did not react to the drone’s presence or else moved slowly away. The drone study of Whooper Swan breeding productivity was considerably faster (9 min per site vs 1–2 h ground survey), more precise, and less invasive for the birds than a traditional ground survey.