Birdsong starts out as audible vibrations created when exhaled air passes over the membranous lining of the simple tubular voicebox – the syrinx.
Located at the base of the windpipe, the syrinx is an arrangement of cartilage, muscle and vibratory membranes over which exhaled and inhaled air passes, and can generate sounds of extraordinary complexity. Muscular changes to the membranes’ tension control the pitch, and the rate of airflow regulates volume.
This raw sound is sculpted further by the shape of the throat and mouth. Sitting at the point where the windpipe splits to supply the lungs, the syrinx can produce different sounds from each side simultaneously.
Some birds can even exhale through one side while inhaling through the other, allowing them to sing for longer without pause – some are even able to produce two notes simultaneously. The tongue plays no part in bird song, except among parrots.
Did you know the brown thrasher bird (below) from North America can produce 3000 different song types due to the ability to mimic other birds?
While the accolade for the loudest bird in the world goes to the male white bellbird