At night, a flock of white pigeons flew across the sky and barked.

It's pigeons wooing with pigeon whistle.

There are many different materials for pigeon whistle, as well as the bearing capacity of pigeon itself, weather and wind, so the sound is different.

This is a normal phenomenon. In addition, even male pigeons in pairs will call and follow other pigeons, and will only be quiet when they are in the nest with their spouses.