Wood thrush. Original public domain image from Flickr
For many, the flutey, trilling song of the Wood Thrush is the sound of the forest in spring and summer. It echoes through ravines and off hillsides. How do they produce such a hauntingly ethereal sound? Unlike humans, the Wood Thrush has a Y-shaped syrinx, allowing it to sing two notes simultaneously! This comes in handy as the males compete to see who can sing the most unique and beautifully self-harmonious song. Credit: Michael Schraam/USFWS. Original public domain image from Flickr