If you’re worried about the increasing number of drones that fill the skies, perhaps you should just chill out like birds do. In an effort to establish ethical guidelines for observing our feathered friends, scientists approached mallards, flamingos, and greenshanks with a quadcopter drone more than 200 times and watched for signs of disturbance. The researchers varied the color of the drone from black to blue to white; they approached at speeds of 2, 4, 6, and 8 m/s; and they approached at angles of 20°, 30°, 60°, and 90°. According to the results published online today in Biology Letters, the drone’s speed and color had no effect on whether the birds were bothered by the drone. The only variable that perturbed any of the three species was the angle of approach: When the drone dropped down on the birds from directly overhead (90°), all three species showed signs of disturbance such as moving away from the drone or flying away entirely. No other approach angles appeared to irk the avians at all. Although this is encouraging for the future of drone observation, scientists point out that the birds may be experiencing stresses that aren’t obvious to observers, such as increased heart rate or adrenaline flux. And although flamingos and greenshanks are known for their high sensitivity to disturbance, they’re not representative of all birds. In particular, the researchers point out the wealth of Internet videos depicting birds of prey attacking drones.