Songbirds include those birds from the order Passeriformes, commonly called passerines. There are approximately 5,400 different species of passerines. The suborder Oscine includes those birds that we tend to think of as your typical songbird, those birds that have complex songs as adults. In the majority of Oscines, the male is the one with the complex singing ability, and there is much diversity among males of different species in the length and complexity of their songs.
Song needs to be developed, just like any other characteristic of songbird behavior. Singing the correct song for that species is not an instinctual process. The need to sing is instinctual, however what song to sing has been found to be learned. When and where young songbirds learn their songs has long been studied. Just as songbirds differ in their songs, they also differ in their song learning process, though some basic principles seem to be the same. Many species learn their song only during the first few months, though a few can learn songs their entire lives. Also differing between species is from who the songs are learned, and how much of the songs are accurately imitated.
Some species may exactly copy the songs they are exposed to. On the other hand, many will not exactly imitate the song or songs that they have been exposed to. Instead they will take bits and pieces of it and invent their own song, though usually similar in construction to that which the species normally sings.
bits and pieces：曲子的部分调子或小节
The Basic Features of Song Learning
Nine males song sparrows were collected from the wild from four different broods when they were around 4 to 6 days old. They were raised by people until they were weaned at 33 to 35 days old and then were placed into individual wire-mesh cages. Live tutors were used in this experiment. Four wild-caught adult male song sparrows were used as the tutors. The tutors were placed into flight aviaries and the subject’s cages were placed adjacent to the aviaries, so that they could have visual contact with one of the tutors, while still being able to hear the other three singing. Also, the subjects were rotated so that their visual contact with one tutor varied between the tutors. The subjects were there when they were 33 to 94 days old, with the assumption that their sensitive phase lay some time in this time period.
When the subjects started singing the next spring, their repertoires were analyzed. The average was seven song types per subject. This does correspond with birds raised exclusively in the wild by their parents. Eight of the nine subjects learned songs from two or more of the tutors and later imitated these songs.
In similar experiments in which some birds are exposed to tutors and some are raised in isolation, those birds that were exposed to tutors almost always tend to imitate pieces and even complete songs. Those birds raised in isolation always sang isolate songs. These isolate songs were similar to each other and consist of much more structurally simpler songs than males raised with normal song exposure.
song sparrows: 北美歌雀
Sensitive Learning Period
There seems to be a specific time period in which songbirds learn their songs. This “sensitive phase” is “when an individual hears and is thought to acquire song models” (Peters et al. 1992). Most species learn their songs as juveniles. This learning period lasts from around ten to sixty days of age. This learning period corresponds very closely with the age at which baby birds are in a rehabilitators care. The songs that they are exposed to during this time period are what they will learn from and start singing once they mature. Songbirds do not start to sing until the next spring, once they are around three hundred days old. Once they start to sing, they only imitate songs that they heard during their early sensitive phase. Just a few passerines, such as the European Starling, “are capable of learning songs later in life”.
There is some controversy as to whether live tutoring leads to a longer sensitive phase than does tape tutoring. However, recent experiments show that there is little to support this view.