W. H. THORPE 



85 



ill 1954-55 with iour wild-caught birds given such tuition in the winter 

 (January 6th-20th) and with three birds similarly treated in February- 

 March showed clearly the effect of the 'song tutor', there being correct 

 articulation of the phrases and a good approximation in pitch and quality, 

 although there were abnormalities in length and emphasis. If, however, 

 under these conditions one exposes the young birds to highly abnormal 

 songs, no result is obtained. Thus in experiments in 1955-56 such birds 

 were given tuition with a reversed chaffinch song during March. The fact 

 that no definite effect was obtained suggested that enough of the song had 





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25 



Figs. 5 and 6 

 Two sons of a hand-reared auditory isolate after having been 

 exposed to normal song on the 'song tutor' for lo days only during 

 November of its first year. GY/BW, April 24th, 1956. 



already been learned in the autumn for the reversed song to be ineffective 

 even with visually isolated birds. In 1956-57 a similar experiment was 

 done using six wild-caught autumn males and exposing them in this case 

 not to a reversed song, which was thought to be perhaps too abnormal, 

 but instead to three different 're-articulated' songs (these are songs in 

 which the position of the three phrases has been interchanged). In this 

 experiment the birds were isolated in a sound-proof room. Two birds 

 had exposures in September and October, repeated in January, two had 

 exposures in mid- to late-October and late January and early February, 

 and two were similarly exposed in November and February. On the 



