Song learning has been taught successfully in the lab in a variety of ways. The two most commonly used teaching practices are by using a tape tutor and the use of live tutors. Tape tutoring is playing a recording of a song, or multiple songs over and over. Live tutors are adult males of the same species kept either in the same cage as the babies, or in adjacent cages so that the young can both interact with and hear the adults singing.
Many species can learn songs equally well from either taped songs or live tutors. Some species, however, have had limited, if not zero success learning songs from a tape and have only been recorded in lab learning from live tutors. In addition, the age at which learning occurs may differ from live to tape tutors. This difference in learning success, however, may have to do with how often the birds are exposed to the tape versus the live tutor. If they are with the live tutor all day long and he is singing all day long, there will be much more exposure than just hearing a taped song a few times during the day.
Studies performed on hand reared chipping sparrows and field sparrows have shown no learning from tape-recorded songs. Instead their songs were highly abnormal and were similar to babies raised without the benefit of hearing any song whatsoever. When exposed to live tutors, however, both species have been shown to learn to properly sing.
重点词汇：
multiple：多种的，多种多样的
interact：相互影响，作用
hand reared：人工抚养的
properly：适当地，真实地，符合习俗地
The question now arises as to how often babies need to be exposed to songs in order to learn them. Most experiments “expose test subjects to hundreds or even thousands of repetitions of tape-recorded song models over the course of training” (Peters et al. 1992). There have been a few studies performed in which babies were exposed to much less tutoring. One study done on song sparrows showed that “song sparrows are capable of learning from 30 repetitions of a song type heard in a single 5-minute bout” (Peters et al. 1992). The experiment was performed on nine hand-raised song sparrows. The subjects were raised out of auditory contact with other birds until they reached 50days of age. This experiment exposed song sparrows to taped songs varying from over 1000 presentations of the song for a four week time period, to 30 presentations of a song over one five minute time period. Both groups learned their songs equally well. Also, some of the most successful learning experiments only played the songs to the birds twice a day, once in the morning, and once in the evening. Of course, one must keep in mind that this experiment was only performed on song sparrows, and the results may differ dramatically in other songbird species.
Since we have now gone over, what and when birds learn, next we will go over how birds learn. Birds exposed to songs of a different species do not start imitating that song. Instead they seem to know to only imitate songs coming from conspecifics. They have the ability to discriminate between songs of their own species and those of other species. Interestingly enough, nestlings and fledglings even respond differently when exposed to their song versus a song from another species. In one experiment, “fledgling white-crowned sparrows called more vigorously in response to playbacks of songs containing conspecific phrases than to playbacks of songs containing heterospecific phrases” (Soha & Marler 2001). Somehow, babies are able to discriminate between their song and others, even prior to the sensitive phase of learning.
Research seems to suggest that there are specific acoustic cues involved in the learning process. These cues seem to be in the length, tone and pitch of the introductory whistle of a song. In fact, one group of researchers was able to get white-crowned sparrows to successfully imitate heterospecific songs, by just adding their introductory whistle. Certain conspecific phrases are used as cues to discriminate between conspecific and heterospecific songs 重点词汇：
Imitate:模仿，把……作为例子
Conspecifics: 同种个体
Discriminate:分别，歧视，有差异的对待
Nestlings:（还不能离窝的）雏鸟
Fledglings:刚学会飞的幼鸟
Vigorously:精神旺盛地，活泼地
Heterospecific: 异种的
Acoustic:声音的，听觉的
Pitch: 音调，音高