"though once they are bowed
So low for long, they never right themselves:..."See in text(Text of the Poem)
This description of the birches represents an example of both personification and the pathetic fallacy. The speaker subtly imagines the birches as people “bowed/so low for long, they never right themselves.” As the poem unfolds, it becomes increasingly clear that the speaker views himself as such a person, particularly when comparing himself to the carefree, birch-swinging boy he once was.