Effects of behavioural time budgets and nest-building efficiency on male reproductive performance in red bishops (Euplectes orix)

Abstract

In this study we have investigated the effect of nest-building behaviour, courtship behaviour, and male–male interactions on male reproductive performance of the red bishop (Euplectes orix), a highly polygynous, colonially breeding weaverbird species. Previous studies on red bishops have revealed that male reproductive success is mainly determined by the number of nests built in a territory, and that reproductive success and the number of nests both vary substantially among males. Here we test whether the high variation observed in reproductive performance is related to male behavioural patterns (as assessed by time-budget analysis) and/or nest-building efficiency (as assessed by the number of fibres incorporated in the nest in unit time). We collected data on male time budgets and analysed behavioural patterns for three breeding seasons. A greater number of nests built was positively related to both the amount of time allocated to nest-building behaviour and the efficiency of nest building. Neither the amount of time spent in courtship behaviour nor the amount of time spent in male–male interactions was related to reproductive success. Male reproductive success, irrespective of the number of nests built, was partly determined by the number of fibres incorporated, suggesting some importance of nest quality in terms of nest chamber density to male reproductive success. There were no trade-offs with regard to time allocated to different behaviour. Instead, males differed with regard to their territory attendance and activity levels, which might be because of differences in energy resources and may thus reflect inherent differences in male body condition and, ultimately, male genetic quality.