So the song is just another way of enticing more replication. The Flower is just a ploy to help all those molecules and systems of order to make copies of themselves, for the sheer sake of copying itself. The fruit is selfish too. My problem with secular humanists is that there are so many joy giving things in Nature that it does not make any sense to evolve that highly, that pretty, that cognitively, or that complicated. A Humanist would shoot back, that the more evolution, the more replication, the better.
Evolution is all about diversity, organization, systems and success.
So to the humanist the song of a bird is not a song but an instict inspired by evolution that will lead to replication. Take all the beauty of Nature out of life and remember that we and all around us are just selfish molecules. To be a secular Humanist is to strip naked the beauty of the countless systems that compose the universe, Life on earth and the mind itself. If you don't believe in the watchmaker, you are a fool. If you don't belive in a Creator, you are an athiest.