Bird song in La Belle Dame Sans Merci

Something that I found odd about La Belle Dame Sans Merci was that the mention of bird song is only the lack thereof. In many of our readings bird song is used to show the beauty and happiness in something as simple as one small aspect of nature. Although this poem describes the emptiness and unhappiness that exists without bird song, I thought it was interesting that Keats did not mention bird song in the happy memories of the Knight. I began to wonder how mentioning bird song in a positive way would have changed the meaning of the poem. I think had he referenced a happier song, or just the existence of bird song during his tryst with the woman, it would have made the relationship more real and less superficial. The footnote describes the woman as a "supernatural femme fatale" and in the poem, it is clear that she has always taken advantage of men, telling them she loves them and then leaving them. This is evident in stanza ten, when Keats describes the dream, "I saw pale kings, and princes too, / Pale warriors, death pale were they all;/They cried --"La belle dame sans merci/ Hath thee in thrall!" (37-40). Here, Keats points out that this woman seduces any and all men, from royalty to warriors, and leaves them all broken hearted and emotionally devastated. He then goes on to say that this knight is just another one of her conquests, further proving that this woman only uses men and then leaves them. This moment in the poem cements her character as being superficial and cruel. If he had used the bird song to describe their relationship when the knight was happy and the relationship appeared loving, it would have made it seem much deeper than surface value. I think this would have ultimately weakened the poem. Bird song would have heightened the joy and added value to the love that the knight was feeling. This may have made the emotional reaction of the knight more pitiable, but it also would have changed the meaning of the poem. The woman's character would've been changed and it wouldn't have made as much sense because if the audience thought her relationship with the knight was genuine, the knight's dream would have made him a lot more conflicted. If that were the case, the poem would most likely have had to go on for several more stanzas, or risk the ending seeming too abrupt.