system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do mourning doves make that sound when they takeoff flying?
gpt
It's due to the shape of the feathers on the wings. Specifically, the flight (bigger) feathers closer to the body are shaped such that they produce a vibration that creates the whistling. It's thought that the sound may serve as a warning signal to other doves.