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.