Zinya, yes, I should have said "human audience" -- surely that bird would like to be heard by another. But are we sure it's about mating?

I think you're right that Hardy's really careful about employing verbs (like that conditional tense in "I could think") that point to an epistemological work going on, a process of volition and decision-making being applied to perception: how do I see what I see, and how do I go about my knowing? Which would suggest that he's a precursor of Stevens? Thirteen ways of looking at what the thrush said?