BACKGROUND/DISCUSSION

　　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.

　　重点词汇：

　　Passerine：雀形目的，雀形鸟

　　Oscine：鸣禽类的，鸣禽类的鸟

　　Instinctual：本能的

　　Principles：原则

　　Imitate：模仿，效仿

　　exposed to：曝露于，公开揭露

　　bits and pieces：曲子的部分调子或小节

　　点拨迷津：

　　重点内容是在第二段和第三段，告诉我们鸣禽类唱歌是一种本能，但是如何去学会唱歌的是实验所要研究的问题。虽然每种不同的鸣禽有不同的学习过程，但是有一些基本的原则是相同的，例如大部分的鸟都是在出生的前几个月学习唱歌。另外一个要关注的问题就是鸟类是不是准确地模仿到了自己所听到的歌声。

　　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.

重点词汇：

　　song sparrows: 北美歌雀

　　broods：窝

　　aviary：鸟舍

　　subject：实验的对象

　　adjacent to：与…连接的

　　rotated：旋转的

　　repertoires：整段乐曲

　　correspond with：相符合，相一致

　　exclusively：专门的，排外的

　　isolation：孤立，隔离

　　点拨迷津：

　　这是介绍了一种类型的实验，实验一是对9只刚出生的北美歌雀统一进行的，另外一种实验是以实验对象分组进行的。

　　统一进行的实验总结如下：

　　实验对象：9只刚出生的北美歌雀

　　实验材料：4只成年的北美歌雀

　　实验过程：让9只小鸟由人抚养一个月之后放入到实验笼中，而在其另一边放上有4只成年鸟的笼子。幼鸟能轮流看到其中一只成年鸟，但是可以听到所有成年鸟的叫声。

　　实验结果：平均每只鸟会有7种类别的歌声，9只中有8只都学到了2种或者2种以上的成年鸟的叫声。

　　分组实验总结如下：

　　分类：看的到成年鸟                             隔离抚养

　　歌声：模仿，完整的片段，结构复杂               单一，雷同，结构简单

　　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.

　　重点词汇：

　　Specific：特定的，特有的

　　Acquire： 获得，得到，养成

　　Mature：成熟，长成

　　European Starling：欧椋鸟

　　Controversy：争论，论战

　　点拨迷津：

　　鸟类学习唱歌基本上会有一个特定的时间段——“敏感学习期”，在这个时间段内，一般是出生10到60天左右。在这段时间内听到或者学习到的歌声，会在小鸟成熟后开始唱歌后体现出来，一开始唱出的内容就仅仅是模仿在“敏感学习期”所听到的内容。但是有一种欧椋鸟却是可以在成年以后也能继续学习唱歌的。

　　有一个争论是认为听成年鸟的现场歌声学习的幼鸟的“敏感学习期”要比听录音学习的幼鸟的“敏感学习期”长，不过这并没有实验支持。