| The clear tones of birdsong emerge from internal air sacs that can inflate and deflate, much like a bagpipe's bladder. |
| Alone in a suburb of the same city, my husband away, one afternoon I mistook birdsong for a person whistling inside the house. |
| Listening to recorded birdsong is only one of many ways on the Internet to tune in to real animal voices. |
| Many studies have been done exploring the degree to which birdsong is innate or learned behavior. |
| It was almost impossible for the similarities between birdsongs and music to be a coincidence. |
| Some calls have around seven rhythm patterns and are comparable to birdsongs and whalesongs. |
