I'm glad you like it! The song is Satie- Gymnopédie No. 1, but I think it's used online quite often :p
On the one hand I agree that making the ducklings stand out more would help (I think they sometimes spawn inside rocks and things like that), but finding them, to some extent, is of course also part of the challenge. We might get back to the game and make some improvements after the rating period has ended.
Thank you for your feedback :)