I'm kind of new to playing Twine games. This is probably only the second or third one I've played, but your game definitely has more art than I've seen in the others and I appreciate that. There's a lot you can say with text alone, but sometimes it's just nice to have a picture in there and I find it adds to my experience. Like some others have said, I enjoyed the water colors.
I read the poem quick before playing this, and you seemed to hit the nail on the head. I also like the twist you added to the end making it about the creator of the hummingbird and not the actual hummingbird. I would have liked some hummingbird tweets or hummingbird fluttering noises -- I found it interesting that neither the original poem nor your game dealt with what the hummingbird sounds like.