Singing like bird was also a common expression for a caught criminal who provides the police with information, often for a deal. You hear it a lot in old gangster movies.

sing like a bird: to divulge secrets with little coercion https://www.phrases.com/idioms/sing-like-a-bird

So when do birds sing? When they're caught/caged.

Singing like bird was also a common expression for a caught criminal who provides the police with information, often for a deal. You hear it a lot in old gangster movies.

sing like a bird: to divulge secrets with little coercion https://www.phrases.com/idioms/sing-like-a-bird

So when do birds sing? When they're caught.

Singing like bird was also a common expression for a caught criminal who provides the police with information, often for a deal. You hear it a lot in old gangster movies. sing like a bird: to divulge secrets with little coercion https://www.phrases.com/idioms/sing-like-a-bird

So when do birds sing? When they're caught.