SONG LEARNING AND PRODUCTION IN THE WHITE-CROWNED SPARROW - PARALLELSWITH SEXUAL IMPRINTING

Although vocal learning is widespread among birds, sexual imprinting a ppears to occur in more avian orders. The four features which LORENZ ( 1935) considered essentials of sexual imprinting have parallels in the song learning literature: these are 1. an early sensitive phase, 2. i rreversibility, 3. completion of learning long before manifestation, 4 . supraindividuality. These principles are still sound under certain e xperimental conditions, but LORENZ's ideas require modification in lig ht of more recent data derived from experiments and field observations . The aspects of sexual imprinting stressed by IMMELMANN (1972) are al so examined. These include: 1. sex differences, 2. sibling effects, 3. social aspects, 4. stimulus filtering. The 'consolidation' effect des cribed by IMMELMANN et al. (1991) finds a parallel in bird song in the phenomenon of 'matched countersinging'. It is concluded that the larg e variations encountered in both imprinting and song studies are not a rtifacts of subtle differences in experimental conditions, but represe nt true variation inherent in natural populations, and this variation is subject to the forces of natural selection.