Why do you think that they used a mechanical nightingale, instead of a real one?

she is outspoken and direct

people wont do this for 10 points you need at least 50

  this riddles' answer is library.

  the "leaves" are a reference to the books' pages that the library contains; the branches are a network of libraries that connect multiple libraries' collections, resources, and items in a system of a common database, integrating them; the branches' organization are a useful management tool for coordinating the multiple collections many libraries have.