What is some evidence for why the raven in Edgar Allen Poe’s “The Raven” could be real?

I already have two and need one more.

- The raven saying “Nevermore” is plausible since ravens can mimic speech, especially when domesticated. The speaker states that the bird probably learned the word from an unhappy master.

- The tapping sound that the speaker hears came from the raven that wanted out of the storm. The speaker mistakes the tapping for knocking at first since he was dreaming.