Song sharing and repertoire size in the sedge warbler, Acrocephalus schoenobaenus: changes within and between years

The complex song of the male sedge warbler functions mainly in sexual attraction and the evolution of repertoire size is driven primarily by female choice. As male song ceases upon pairing, male–male singing interactions are relatively brief and have not been studied to our knowledge. This study shows that young males in their first breeding season shared significantly more syllables with their nearest neighbour than with their fathers or more distant males. Moreover, daily recordings revealed that rapid learning and modification of syllable repertoires occurred, resulting in a progressive increase in sharing within just a few days. This does not lead to a gradual increase in repertoire size as some syllables are dropped and new ones are acquired. This turnover process allows males to share syllables with their neighbours, whilst repertoire size, known to be important in female choice, remains relatively constant in any one year. Individual males were followed for several years and also showed considerable syllable turnover between years. However, in this case, repertoire size was found to increase between years, the largest increase occurring between the first and second years. We obtained a significant positive correlation between repertoire size and age, suggesting that females choosing males with larger repertoires may gain indirect (genetic) benefits for their offspring, such as good genes for viability. Whilst these results reveal a more flexible picture of repertoire turnover than previously suspected, the relative stability of repertoire size within a season and the increase with age suggests that repertoire size remains a likely target for sexual selection by female choice.

Qabus ibn Wushmagir : a study of rhythm patterns in Arabic epistolary prose from the 4th century AH (10th century AD)

This study focuses on the Arabic prose style of Qabus ibn Wushmagir, a Persian ruler of the 4th century AH (10th century AD). Through a textual analysis of a selection of his letters it identifies some fascinating rhythmical patterns using the statistical technique of log-linear modelling. The quantitative analyses are based specifically on syllable patterns in the texts which are evaluated according to the theme of each letter. The study concludes that in some letter types in particular there is a certain predictability in the rhythmical patterns of the text which indicate that the style of a given piece was determined to some degree by the theme of the letter.