These birds create amazing black 'clouds' in the sky

Following is a transcript of the video.

No... these aren't storm clouds. They're tiny songbirds known as starlings. Starlings flock together in thousands. Their shifting movements are called "murmurations."

How can they fly so close without bumping into each other? It's a mysterious miracle! The mystery has fascinated scientists in many fields. Biologists, physicists, and engineers have all tried to solve the problem. One theory is that individual birds follow their neighbors' lead. There are nearly 120 species of starlings. You can find multiple starling species within the same murmuration. During murmuration, starlings are constantly on the move. The unpredictability of their shapes is a mesmerizing phenomenon.