Alert and Flight Initiation Distances of the Coot in Response to Drones

Alert and flight initiation distances are important elements of bird behavioral responses and indicators of their adaptation to external disturbances; therefore, they provide an important basis for bird conservation. With continual rapid advancements in drone technology, the use of drones in bird field surveys is becoming increasingly important. However, the disturbance impact of drones on birds remains controversial and needs further assessment. This study measured the distances at which coots (Fulica atra) tolerated drones in the Baiyangdian wetland, Northern China, over 42 days from August to November 2023 and at the end of July 2024. The results show the maximum alert distance (AD) and maximum flight initiation distance (FID) of the coot to be 44 m and 35 m, respectively. The coots showed no signs of disturbance when the drones flew at an altitude of 50 m. The AD of the coot showed a significant relationship with whether it saw the drones in advance, environmental conditions, and the drone’s behavior before it approached, whereas the FID was only significantly affected by whether the coot saw the drones in advance. The sight of drones in advance considerably increased the AD and FID.