So, we know this poem was written over 150 years ago, and we're sure that people talked differently back then. Still, we're not sure you would have met a lot of people in 1845 who walked around shouting things like: "Quaff, oh quaff this kind nepenthe!" (line 83).
Our speaker is definitely the melodramatic type. He starts out at an emotional level of about nine on a ten-point scale; he then heads right through the roof to about fifteen. His tone is intense, almost frantic. He seems super-focused one moment, and then a bit spaced-out the next. Now granted, he's had a tough night, but from the sound of his voice and the choice of his words, we get the sense that he's wound pretty tight even when he's not talking to birds.
We don't mean to make fun of him, just to point out that he seems to live pretty close to the edge. In fact, it's his intensity that makes him so captivating. Like a mad scientist on the edge of a discovery, his tone is pretty exciting. He makes the events of his life as electrifying for us as they are for him.