Avian song learning occurs in two stages: first, songs must be memorized and, second, they must be practiced. In some species these two events overlap, but in others memorization can occur before practice by several months, providing an impressive example of long-term memory storage. ① The young bird’s initial efforts to reproduce the memorized song are usually not successful. ② These early songs may have uneven pitch, irregular tempo, and notes that are out of order or poorly reproduced. ③ However, sound graphs of songs recorded over several weeks or months reveal that during this practice period the bird fine-tunes his efforts until he produces an accurate copy of the memorized template. ④ An important idea to emerge from the study of birdsong is that song learning is shaped by preferences and limitations. ⑤ This process requires hearing oneself sing; birds are unable to reproduce memorized songs if they are deafened after memorization but before the practice period.
* avian: 조류의