Cabaret: big screams and scary pigeons

Title: Cabaret
Year: 1972
Director: Bob Fosse
Running time: 123 min.
Country: United States

We are in Berlin in 1931, Miss Sally (Liza Minnelli) is trying to seduce Brian (Michael York), a British teacher. On their way back to Sally's apartment, she rushes under a railway bridge when a train is passing and screams very loudly. The relationship between the train and her behaviour is not clear, but she seems to be hysterical. Her scream is so loud that a flock of pigeons flies away very scared. Why do the pigeons flee? Was it because of the train? I don't think so.... it was the superhuman Sally's scream.This scene can be seen here.

Details of the pigeon starring 

• Source: Cabaret. Starring moment: 0:21:26
• Pigeon activity: A flock of pigeons flying away from a terrific scream.
• Symbolism: It is well known that pigeons don't like to fly during night time. They have poor night vision and are very vulnerable to predators or night accidents. But in this case they fly way. Pigeons are used to symbolize that Sally's scream was so strong that even the pigeons were scared of it. Maybe it was the almost-sexual nature of the sound.
• Relevance: Negligible. They are mere spectators of  Sally's crazy behaviour. 
• Training level: Not clear. The scene was probably recorded in a studio. In this case, the train bridge is artificial and the pigeons are not wild. Alternatively, it was recorded under a real bridge and we are dealing with wild pigeons that were actually scared in their natural habitat.