Laura Helmuth in Scientific American:
Science is all about expanding the realm of human perception. Sometimes that means making the invisible visible, like when Galileo turned a telescope toward Jupiter, discovered moons around another planet and changed our literal worldview. We now know that flowers, as beautiful as they are to us, are communicating with birds and bees using ultraviolet patterns we can’t see and that elephants can feel vibrations travel through the ground from miles away.
People have been observing birds singing and calling since there were people. Birds vocalize to attract mates, defend territory, find one another, and more. Many birds’ songs sound musical to us, with distinct notes that are repeated in pleasing patterns at a steady speed—melody, rhythm and tempo, basically. But as Adam Fishbein and other bird researchers have discovered recently, what sounds so entrancing to us isn’t that meaningful to them. Birds don’t seem to listen to the melody so much as to fine details within each note that humans can’t detect.
More here.