Behaviour, Volume 141, Number 5 (2004) http://zerlina.ingentaselect.com/vl=9091254/cl=21/nw=1/rpsv/cw/www/brill/00057959/v141n5/contp1-1.htm
(Abstracts below) Radford, AN (2004) Voice breaking in males results in sexual dimorphism of green woodhoopoe calls. Behaviour 141: 555-569. Pasteau, M, L Nagle & M Kreutzer (2004) Preferences and predispositions for intra-syllabic diversity in female canaries (Serinus canaria). Behaviour 141: 571-583. --------------------------------- - Abstracts - Radford, AN (2004) Voice breaking in males results in sexual dimorphism of green woodhoopoe calls. Behaviour 141: 555-569. Abstract: Ontogenetic changes and sexual differences in the acoustic structure of green woodhoopoe (Phoeniculus purpureus) 'kek' calls were investigated in a wild population. At fledging, the calls of males and females were indistinguishable in terms of fundamental frequency, frequency modulation, peak frequency and call duration. After 3-5 months, however, the male voice 'broke' (i.e. underwent a significant decrease in fundamental frequency), while there was no change in female call structure. Consequently, the fundamental frequency of adult male calls was 48% lower than that of adult females, and there was no overlap in the call frequencies of the sexes in adulthood. The change in male voice occurred within a 23 week period and no intermediate call frequencies were recorded. The timing of the voice break did not correspond with a change in overall body size, suggesting that growth of the syrinx was not the proximate cause. However, it did coincide with the stage in development when male bill length grew to exceed that of all females and when males began to lose their distinctive brown throat patch, providing some indirect evidence that hormonal control may be important. Pasteau, M, L Nagle & M Kreutzer (2004) Preferences and predispositions for intra-syllabic diversity in female canaries (Serinus canaria). Behaviour 141: 571-583. Abstract: The aim of this study is to examine the preferences of female canaries for a particular cue in male song: the intra-syllabic diversity (number and form of notes constituting a syllable) and to test both the role of predispositions and of song experience in the development of these preferences. Two groups of females were used. The first consisted of adult females raised in acoustic isolation without song males experiences (ISO group); the second, of song experienced adult females raised with singing male in an aviary (AVI group). Female preferences for intra-syllabic diversity were evaluated using the behavioral index of copulation solicitation displays (CSD). Five different types of songs were tested: three were made up of poor intra-syllabic diversity and two were made up of great intra-syllabic diversity. The results demonstrate that, in each group (AVI and ISO), intra-syllabic diversity is preferred to intrasyllabic simplicity. In addition, the inter-group comparison showed no significant differences between the two groups. In the aviary group, song learning by sexual and sound experience did not seem to modify or influence the intra-syllabic diversity preferences. Thus, female preferences for such a diversity would result from early predispositions that are maintained in adulthood.
