Sensitive Phase For Song Learning Research Articles

Vocal imitation in blindfolded zebra finches ( Taeniopygia guttata ) is facilitated in the presence of a non-singing conspecific female

Song acquisition in young male zebra finches, Taeniopygia guttata, is viewed as a learning process by imitation from a visible conspecific male acting as a song tutor. The role played by non-singing conspecific females in this process has been poorly documented. The influence of social contact on the song learning of blindfolded young males was investigated in both female-raised and pair-raised birds. Pupils with both eyes occluded from about 35 to 65 days post-hatch, the sensitive phase for song learning, copied significantly more from an adult male sharing their cage when tutored in the presence of a female sibling than in her absence. Interestingly, the effect was more pronounced in female-raised birds compared to pair-raised birds. I conclude that physical contact in the absence of visual cues is sufficient for song imitation to occur. The results demonstrate an instance of social stimulation by non-singing females in the song acquisition of male songbirds.

Song learning from playback in zebra finches: is there an effect of operant contingency?

Social interaction is often regarded as crucial for song copying in zebra finches,Taeniopygia guttata. Contingencies in the interaction between pupil and tutor might be essential for the song-copying process. The effect of contingency between a pupil’s operant behaviour and tutor song has been studied previously, but with contradictory results. Our aim in this experiment was to provide a more rigorous test of the effect of operant contingent exposure to song playback in zebra finches. Eight experimental males were trained to expose themselves to tutor song by operant key pecking during their sensitive phase for song learning. Each bird had a yoked control, which heard the same tutor song at the same time. All birds were acoustically isolated. The results were surprising in two ways: (1) the control birds copied song to which they were passively exposed; and (2) the experimental birds did not copy more than the controls did. So, we found no effect of operant contingency on song learning. Furthermore, when tested as adults all but one male preferred the tutor song to an unfamiliar one. We conclude that zebra finches can copy playback song, and that social interaction is not crucial for song copying, although it might still be facilitating.

External validity and experimental design: the sensitive phase for song learning

In the past decade there has been widespread acceptance of the idea that the use of live, socially interactive tutors in song learning experiments produces results that differ dramatically from, and are more valid than, results obtained with tape tutors. The influential series of experiments by Baptista & Petrinovich (1984,Animal Behaviour,32, 172–181, 1986,Animal Behaviour,34, 1359–1371; Petrinovich & Baptista 1987,Animal Behaviour,35, 961–974) have promoted this view, and their results have been widely accepted. Baptista & Petrinovich's results have led them and others to question whether there are age-limited sensitive phases for song learning, as Marler's (1970,Journal of Comparative Physiology and Psychology Monographs,711–25) early studies on the white-crowned sparrow,Zonotrichia leucophrys, suggested, and led them to argue that interactive tutoring produces essentially open-ended learning. I argue here that this view is mistaken, and that the sensitive phase for song learning in the white-crowned sparrow is identical for live and tape tutors and is restricted to the first few months of life. Baptista & Petrinovich presented live and tape tutors for different periods to their subjects. Type of tutor (live versus tape) is confounded with duration of exposure to tutors. As a consequence, their experiments confound two different forms of song learning that occur at different ages, and give the mistaken appearance of an extended sensitive phase when live tutors are used.

Do Contingencies with Tutor Behaviour Influence Song Learning in Zebra Finches?

AbstractSocial interaction with a song tutor is often found to be important for the song learning process in songbirds, but the mechanism is still unclear. The main aim of this study is to find indications for contingencies between singing and interactive behaviours, between and within tutors and tutees, which might influence the song learning process of zebra finches (Taeniopygia guttata). To this end we observed the interactions of eleven juvenile zebra finch males with their fathers (the tutors) and their mothers during the sensitive phase for song learning, and examined four different types of possible contingencies. The evidence for these contingencies was not very strong: (1) We found some weak indications that a tutee can anticipate tutor song by preceding tutor behaviour. There were no indications that (2) tutor song is contingent upon subsequent behaviour of the tutor, that (3) juvenile males can control singing of their tutor by preceding operant social behaviour, or that (4) social behaviour of the tutor reinforces singing of the tutee. We found some indications that the juvenile males attend actively to the tutor song. Furthermore, we found that the juvenile males maintained more mutual interactions with their father than with their mother. In general, we did not find any clear relationship between aspects of social interaction and song copying in zebra finches.

Practice and Song Development in Zebra Finches

AbstractMale zebra finches reared by both parents were placed in isolation from day 35 to day 70 of life, the sensitive phase for song learning, and exposed to a singing adult male thereafter. Half the birds were stimulated to practice by a tape of birdroom noise during their period in isolation, and the practice of all birds was monitored. Those that were stimulated did practice more during the period when the tape was on, but the overall amount of practice in both groups was very high, rising to occur in 60-80% of all 10 min monitoring sessions after 50 days of age. Individual differences were considerable. In the unstimulated group, there was some suggestion that birds which practised more had achieved greater song stereotypy on one measure by day 70. However, the hypothesis that birds which practised more would be more likely to develop copies of their fathers' songs was not supported. Instead, the final song of birds in both groups was clearly based on that of the tutor introduced at 70 days. While the results point to a great deal of practice by young zebra finches, they do not suggest that greater practice leads to earlier crystallisation of song or increases the likelihood of copying songs heard earlier.

The Role of Aggression in Song Tutor Choice in the Zebra Finch: Cause or Effect?

AbstractYoung male zebra finches (Taeniopygia guttata) normally copy their song from one tutor when given a choice of two. Interaction is known to be a key feature of the learning process and this study examines the way in which one particular type of social behaviour, aggression, may affect tutor choice. Female raised zebra finches were given a choice of two song tutors, which had been pre-selected for differing levels of aggression, during the sensitive phase for song learning. A young bird was significantly more likely to learn from the tutor that was more aggressive to him, as found earlier by Clayton (1987). In addition, behavioural observations suggest that aggression towards the young bird was the cause rather than an effect of tutor choice. There was no significant relationship between the relative level of tutor aggression and the amount of his song copied. Changes in the level of aggression over the tutoring period are also discussed.

What causes young male zebra finches, Taeniopygia guttata, to choose their father as song tutor?

Abstract. Earlier work suggested that young male zebra finches given a choice between their father and another male during the sensitive phase for song learning prefer to learn from their father. A series of experiments was conducted to discover the reasons for this preference. Evidence presented here, and from work carried out by Böhner (1983, Anim. Behav., 31, 231-237), suggests the involvement of three factors. Birds preferred to learn from the male with which they were housed before the sensitive phase, which would normally be the father. In addition, there was a preference for learning from the male that is paired to the female that had reared them, normally the mother; and a preference for learning from a paired rather than a single male.

Operant conditioning, song learning and imprinting to taped song in the zebra finch

Abstract. Young male zebra finches, Taeniopygia guttata, given control over the presentation of tape-recorded songs, imitated to a greater extent than siblings exposed passively to the same stimulation in an adjacent cage. They also copied more precisely the syntax of the song model acquired before sexual maturity. Thus, operant conditioning with song as reward strongly influenced song learning during development but not song preferences in adulthood. In choice tests using the same techniques, both experimental birds and yoked controls preferred the training song over a new song as well as over their own song. These results provide the first instance of imprinting to an auditory stimulus heard during the sensitive phase for song learning (35-65 days post-hatch) in an oscine species.

Can Lack of Experience Delay the End of the Sensitive Phase for Song Learning?

Some bird species will modify their songs in adulthood, whereas in others, once developed, song appears relatively fixed. However, even in some of the latter, social experience may lead birds to learn songs later than was previously thought possible. Do age-limited learners really exist or is failure to learn later in those species where it has been described a result of inadequate stimulation? If learning is normally restricted to a certain age period, is the decline in sensitivity due to age as such or to enough adequate information having been received? We discuss some of the issues involved and describe some experiments on zebra finches which we have carried out. Our results suggests that drastic changes in adulthood are rare. Birds deprived of tutors in the sensitive phase are more likely to produce elements learnt from the father before that stage, but show little evidence of learning from tutors encountered when adult (at 120 d+). Birds that are female-raised in groups and deprived of any male tutor till 120 days learn little from their tutors thereafter but have quite normal songs; these converge strongly within groups, as do the songs of all group-reared birds. Birds reared by both parents but without siblings, and then deprived of song during the sensitive phase, show learning both from the father and from the tutors encountered after 120 days. The most abnormal songs are those of birds reared by the mother alone and then kept singly till they were placed with singing adults at 120 days. The songs of these birds were more variable than those of the other groups, and they showed more evidence of learning between 120 and 240 days. These results do suggest some flexibility in the timing of song learning in zebra finches depending on experience but argue against profound change occurring once birds are adult even where their early experience has been greatly reduced.

The influence of visual stimuli on song tutor choice in the zebra finch, Taeniopygia guttata

Young male zebra finches, given a choice of two song tutors belonging to different colour morphs during their sensitive phase for song learning, learned mainly from that belonging to the morph of the birds that reared them. When given only one song tutor, of a different morph from their parents, they were more likely to delay learning until after the normal sensitive phase or use elements in their song that were used by the father in his song. In mate choice tests, most young males preferred, a female of the same morph as that of the male from which they had learnt their song, but some did not do so, suggesting that song tutor choice and sexual imprinting are not manifestations of the same learning process.

Song Learning in Zebra Finches Exposed to a Series of Tutors during the Sensitive Phase

AbstractYoung male zebra finches exposed to a series of adult males during their sensitive phase for song learning tended to learn from several of them, in contrast to those exposed to two or more tutors simultaneously. There is a tendency to learn more from later tutors, either because the memory of their elements over‐writes that of earlier ones or because sensitivity is greater at this stage. No clear relation could be found between features of the song or behaviour of tutors and whether or not they were copied. In common with earlier studies, tutor song output, beyond a certain minimum was found to be unimportant.

Song and call learning in wild zebra finches in south-east Australia

Sons of wild zebra finches, Taeniopygia guttata, were studied for three breeding seasons at a colony in south-east Australia to determine if they learnt their fathers' songs and distance calls. Sons, but not fathers, were captured and placed temporarily in an aviary located within the nest bushes of the colony during or after the sensitive phase for song learning (35–65 days); songs and calls were recorded at or after day 100 and the birds released. Distance Calls and the elements that constituted the song phrases of 40 sons and their 20 fathers were recorded and compared in matching tests; sons were also matched with controls whom they encountered during the sensitive phase. Some song elements could match by chance alone so it was necessary to distinguish those matching scores due to chance from those higher scores that indicated a possible tutor-pupil relationship. Likely tutors for 24 sons were identified: 17 were the sons' own fathers, four were controls and two may have learnt from either. Aviary confinement isolated sons from their fathers' tuition so that the younger the sons that were confined, the lower their matching scores with the father. In the only family that spanned three generations, song phrases were transmitted with good accuracy. The Distance Call, which also formed an element in the song phrase, was learnt from the father by 72% of sons. Songs and Distance Calls were individually stereotyped over intervals of many months. Opportunities in nature for song learning from the father are discussed.

Song learning in zebra finches: some effects of song model availability on what is learnt and when

This study indicates that captive male zebra finches ( Taeniopygia guttata) normally learn their song during the juvenile period between independence from their parents and sexual maturity, from whatever suitable song model is available. Virtually nothing is learnt from the father before this time. Hybrid songs may develop if birds are removed from the father and given a new song model before song learning is complete. The absence of a song model during the juvenile stage appears to postpone the sensitive phase and abnormal song is produced until a suitable model becomes available. Normal song will then develop, even in a sexually mature adult. This indicates that experience and not age is the important factor determining the timing of the sensitive phase for song learning in zebra finches.

Vocal learning in White-crowned Sparrows: sensitive phase and song dialects

In a laboratory song tutoring experiment, eight male White-crowned Sparrows learned their natal song dialect, presented to them at 10 to 50 days of age, in preference to an alien dialect, presented to them from 51 to 90 days of age; two males learned the alien dialect, one developed a hybrid song, and one a simple song lacking structural detail (Fig. 3). Three other males developed aberrant songs (Fig. 5). Excepting these three aberrant songs, the song patterns of the males were similar to, though not close copies of, the tutor songs. The songs of all males remained consistent through two photoperiodically induced breeding ‘seasons’ (November–January and April–May; Fig. 4). During these ‘season’, females were induced to sing by administration of testosterone. Six females sang during the first season, eight sang during the scond season, with five singing in both seasons. Unlike those of the males, the song patterns of all females (with the exception of F9), were not similar to the tutor models. The songs of those five females that sang during both seasons remained consistent through both seasons (Fig. 6). We conclude that because the sensitive phase for song learning generally coincides with natal philopatry, White-crowned Sparrows are predisposed to learn their natal dialect which they retain through life. This result may be an important factor in the maintenance of populations structured by geographic systems of dialects.