Seriously, Annie, there's so much to support your reading of the poem -- when I went back and read it thinking that way, two lines in particular jumped out at me:

"An aged thrush, frail, gaunt, and small" which Mark pointed out as well -- Hardy was 60 when he wrote this poem, and "Was written on terrestrial things," the metaphor of writing can of course be thought of as not a metaphor at all! One of my favorite pieces of critical writing for understanding Romanticism is Ruskin's "Of The Pathetic Fallacy," and I think this concept applies of course directly to the Hardy poem.Thanks, that makes the poem even better (which seems to me like the purpose of criticism).