Unacceptable reactions (flushing from the sample plot or attack on the drone) occurred in 52 cases. The average distance from the drone to the birds when this type of reaction occurred was 35.8 m (± min.-max. 15 m – 50 m). In the case of breeding birds, an unacceptable reaction took place in three cases (n = 83) and involved only one species – Black Tern Chlidonias niger ; the reaction was an attempted attack on a drone. In the case of non-breeding birds, unacceptable reactions occurred in 49 cases (n = 260), all of them involving the birds flying off beyond the sample plot. None of the non-breeding birds attempted to attack the drone. The average flock size among birds displaying unacceptable reactions was 317 individuals and was slightly higher than among birds exhibiting no or negligible reactions (291).
Adverse (unacceptable) reactions were recorded in 13 species (n = 33). Anser geese were the most sensitive to the drone’s presence with 35.8% of unacceptable reactions. Gulls were the least sensitive to the drone’s presence: no unacceptable reactions were observed, and the birds were completely indifferent to the drone in 88.8% of cases (Table 3).
Table 3. The behaviour of birds in response to the drone, broken down into groups of similar species. Reaction codes: #0 – no reaction, #1 – slow movement away, #2 – diving, #3 – flushing over short distance flush, bird remained in the sample plot, or quickly returned, #4 – flushed, panic reaction, bird left the sample plot and did not return, #5 – attempted attack on the drone.