Drones disturb birds: Swiss Ornithological Institute issues recommendations

The larger and louder a drone is, and the more directly it approaches a bird, the more intense the bird's reaction.

The Swiss Ornithological Institute has developed recommendations based on a scientific study on how disturbances can be reduced.

Drones as a new threat to wildlife

Drones are being used more and more frequently and for a wide variety of purposes. The problem is that they move through airspace — the very domain where birds have largely been undisturbed until now. This raises the question of whether, and to what extent, drones are perceived by birds as intruders or as a threat. The Swiss Ornithological Institute has compiled and analysed the current state of knowledge on the impact of drones on birds and other wildlife.

The study shows that birds react more strongly to drones than other wildlife as a general rule. However, there are differences even among birds. While some species merely display heightened alertness, others take flight even when a drone is still far away. Birds often appear not to react to drones at all — though this does not necessarily mean the drone has no effect on them. Nesting birds, for example, rarely abandon their nest even when disturbed. Nevertheless, they may still be under stress.

Factors that influence the reaction

Whether a bird reacts to a drone depends on a number of factors. A direct approach typically triggers a flight response in the bird. Petrol-powered aircraft are more likely to provoke a reaction than electric ones, due to the higher noise levels of petrol engines. Larger drones trigger a greater flight distance than smaller ones. Solitary birds or small groups of birds take flight from drones later than flocks. Finally, it was found that larger birds are more likely to show a reaction than smaller birds.

The Bird Observatory has derived recommendations from these findings on how to minimize the impact of drones on birds and other wildlife. In the coming months, the Bird Observatory will meet with authorities, drone users, and nature conservation stakeholders to develop broadly supported guidelines for the wildlife-friendly use of drones.

Disturbances are a serious and growing problem for wildlife. Particularly alarming is when birds abandon their breeding activities or fail to begin them at all. If a bird or other wild animal is repeatedly forced to flee, there is in extreme cases a risk of death from exhaustion. Protecting wildlife from disturbances is an important aspect of biodiversity.

Recommendations from the Swiss Bird Observatory

• Do not take off or land near birds, and avoid abrupt changes of direction in their vicinity
• Never fly directly toward birds, and turn back immediately if birds show a reaction
• Prefer small and quiet devices
• Avoid flying along cliff faces, especially from February to July, the breeding season of sensitive species such as the peregrine falcon and eagle owl
• Avoid flying in and over nature reserves and maintain a distance of at least 200 m
• Strictly observe flight bans, such as those applicable in water and migratory bird reserves and federal hunting ban areas