Edgar Allan Poe was the master of using symbols in his writings. They symbols always represented something else.
Poe could have certainly used another animal in the story, but the effect wouldn't have been the same. He could have used a parrot, for example, but a parrot can speak many words. There is something ominous about the raven only saying nevermore. In some cultures the raven is seen as a bad sign. There are seen as mournful and never ending remembrance, which is very fitting in this story. The narrator can not get over his love, Lenore. The raven can also represent an ill omen or even death. When the raven sits on the bust of Pallas, this is another symbol for us. Pallas was the Greek god of wisdom. The raven can be seen as wise and having knowledge of something the narrator does not.
Edgar Allan Poe's use of the raven is very symbolic. A raven is midnight black, which the story does take place at midnight. The darkness of the bird is an ominous symbol for the man. And let's just face it, ravens are really creepy birds. We have to ask ourselves, though, are they really creepy, or just creepy because we know the story? Edgar Allan Poe was a master of his work.